283 Users Manual - Princeton Applied Research

283 Users Manual - Princeton Applied Research
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a/k/a Princeton Applied Research, a subsidiary of AMETEK®, Inc.
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Princeton Applied Research* warrants each instrument of its own manufacture to be free of defects in material and workmanship.
Obligations under this Warranty shall be limited to replacing, repairing or giving credit for the purchase price, at our option, of any
instrument returned, shipment prepaid, to our Service Department for that purpose within ONE year of delivery to the original
purchaser, provided prior authorization for such return has been given by an authorized representative of Princeton Applied
Research.
This Warranty shall not apply to any instrument, which our inspection shall disclose to our satisfaction, to have become defective
or unworkable due to abuse, mishandling, misuse, accident, alteration, negligence, improper installation, or other causes beyond
our control. This Warranty shall not apply to any instrument or component not manufactured by Princeton Applied Research.
When products manufactured by others are included in Princeton Applied Research equipment, the original manufacturer's
warranty is extended to Princeton Applied Research customers.
Princeton Applied Research reserves the right to make changes in design at any time without incurring any obligation to install
same on units previously purchased.
THERE ARE NO WARRANTIES THAT EXTEND BEYOND THE DESCRIPTION ON THE FACE HEREOF. THIS WARRANTY
IS IN LIEU OF, AND EXCLUDES ANY AND ALL OTHER WARRANTIES OR REPRESENTATIONS, EXPRESSED, IMPLIED
OR STATUTORY, INCLUDING MERCHANTABILITY AND FITNESS, AS WELL AS ANY AND ALL OTHER OBLIGATIONS OR
LIABILITIES OF PRINCETON APPLIED RESEARCH, INCLUDING, BUT NOT LIMITED TO, SPECIAL OR CONSEQUENTIAL
DAMAGES. NO PERSON, FIRM OR CORPORATION IS AUTHORIZED TO ASSUME FOR PRINCETON APPLIED
RESEARCH ANY ADDITIONAL OBLIGATION OR LIABILITY NOT EXPRESSLY PROVIDED FOR HEREIN EXCEPT IN
WRITING DULY EXECUTED BY AN OFFICER OF PRINCETON APPLIED RESEARCH.
6+28/' <285 (48,30(17 5(48,5( 6(59,&(
A. Contact the Customer Service Department (865-482-4411) or your local representative to discuss the problem. In many cases
it will be possible to expedite servicing by localizing the problem.
B. If it is necessary to send any equipment back for service, we need the following information.
1. Model number and serial number.
5. Your telephone number and extension.
2. Your name (instrument user).
6. Symptoms (in detail, including control settings).
3. Your address.
7. Your purchase order number for repair charges (does not apply to
repairs in warranty).
4. Address to which the instrument
should be returned.
8. Shipping instructions (if you wish to authorize shipment by any
method other than normal surface transportation).
C. U.S. CUSTOMERS — Ship the equipment being returned to:
Advanced Measurement Technology, Inc.
801 S. Illinois Avenue
Oak Ridge, TN 37831
ATTN: Customer Service
PHONE: 865-482-4411
FAX: 865-483-2133
D. CUSTOMERS OUTSIDE OF U.S.A. — To avoid delay in customs clearance of equipment being returned, please contact the
factory or the nearest factory distributor for complete shipping information.
Copyright © 2002, Advanced Measurement Technology, Inc. All rights reserved.
*Princeton Applied Research is a registered trademark of Advanced Measurement Technology, Inc. All other trademarks used herein are the
property of their respective owners.
ii
7$%/(2)&217(176
Safety Instructions and Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
Cleaning Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2. Controlling the Model 283 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2.1. Front-Panel Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2.2. Remote Computer Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3. Operating Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3.1. Potentiostatic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3.2. Galvanostatic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4. About This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
1
1
1
1
2
2
2
3
2. Safety Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2. Power Cord . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3. Line Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3.2. Confirming the Line Voltage Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3.3. Line Voltage Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3.4. Changing Fuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.4. Cell Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.5. Defects and Abnormal Stresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.6. Ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5
5
5
5
5
5
6
6
6
6
7
3. Installation & Initial Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2. Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2.1. Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2.2. Power Cord Plug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2.3. Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2.4. Power Voltage Selection and Line Fuses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.3. Initial Checks Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.3.2. Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.3.3. Power-Up and Cell Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.3.4. Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4. Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2. Cell Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2.2. COUNTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2.3. WORKING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2.4. REFERENCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2.5. SENSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2.6. OVERLOAD Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2.7. CELL Indicator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2.8. CELL ON Key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3. Display/Control Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.2. Mode key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15
15
15
15
15
19
19
19
20
20
20
20
20
21
iii
4.3.3. System key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.4. LCD Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.5. F1 Through F5 Function keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.6. Value knob . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.7. Prev and Next Parameter keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.4. Interface Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.5. Current Range Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.5.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.5.2. Full-Scale Current Range Indicators, 100 mA through 1 nA . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.5.3. key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.5.4. key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.5.5. AUTO Switch and Indicator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.6. BNC Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.6.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.6.2. EXT IN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.6.3. E MONITOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.6.4. I MONITOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.6.5. MUX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.6.6. A/D INPUT I & A/D INPUT 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.6.7. OUTPUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.6.8. D/A OUTPUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.7. Gnd Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.8. Cell Safety Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.9. Dummy Cell Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.10. Power Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
21
22
23
23
23
23
24
24
24
24
24
24
25
25
25
26
26
26
27
27
27
27
27
27
28
5. Back Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.2. Power Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3. Accessory Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4. Auxiliary Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.5. RS-232 Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.6. IEEE-488 Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.7. PA Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.8. A & B Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.9. Expansion Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
29
29
29
29
29
30
30
30
30
30
6. Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.2. Polarity Convention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3. Operating Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3.2. Potentiostatic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3.3. Galvanostatic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3.4. Scanning and Stepping Transitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.4. Controls and Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.5. Using the LCD Menu Screens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.5.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.5.2. Common Screen Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.5.3. Setting Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.5.4. Bottom Row Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.6. Setting Communications Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.6.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.6.2. [System Interface] Menu Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.6.3. [System Interface] Menu Line 3 Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.7. Common Experiment Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.7.1. [System Default] Menu Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.7.2. [System Default] Menu Line 3 Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
31
31
31
32
32
32
32
32
33
33
33
34
34
34
35
35
35
35
36
36
37
iv
Model 283 User’s Manual
6.8. Resetting Parameters to Default Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.8.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.8.2. To reset only the experiment parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.8.3. To reset both groups of parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.9. Calibrating the Model 283 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.10. Determining Installed Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.11. Error Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.12. Connecting a Pen Recorder or Oscilloscope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.13. Adding an External Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.14. Connecting a Model 303A SMDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.15. Connecting a Model 616 or 636 Rotating Electrode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.16. Supplying Accessory Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
38
38
39
39
39
40
40
42
43
43
43
44
7. Running Potentiostatic Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.2. Potentiostatic Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3. Setting Fixed-Potential Experiment Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.4. Setting Scanned-Potential Experiment Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5. Setting Stepped-Potential Experiment Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.6. Running Your Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.6.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.6.2. F1 (Coulombs or offset I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.6.3. F2 (Q-Reset) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.6.4. F3 (Start or Stop) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.6.5. F4 (Hold or Resume) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.6.6. F5 (Reverse or Bypass) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.7. Error Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
45
45
45
46
47
47
48
48
48
48
48
48
49
49
8. Running Galvanostatic Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.2. Galvanostatic Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.3. Setting Cell Current: Special Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.4. Setting Cell Current in a Fixed-Current Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.5. Setting Scanned-Current Experiment Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.6. Setting Stepped-Current Experiment Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.6.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.6.2. F1 (Coulomb or offset I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.6.3. F2 (Q-Reset) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.6.4. F3 (Start or Stop) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.6.5. F4 (Hold or Resume) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.6.6. F5 (Reverse or Bypass) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.7. Error Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
51
51
51
52
52
52
53
53
53
53
54
54
54
54
9. Circuit Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2. Potentiostat Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.3. Galvanostat Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.4. Signal Conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.5. Ancillary Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.5.1. E & I Suppression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.5.2. Auxiliary Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.5.3. Output DACs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
55
55
55
57
59
59
59
59
59
10. Maintenance and Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.2. Battery Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.3. Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
61
61
61
61
TABLE OF CONTENTS
v
APPENDIX A. Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
APPENDIX B. Technical Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
B.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
B.2. Front-Panel Parameters and Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
APPENDIX C. Connector Pinouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C.1. Auxiliary Interface (Mating Connector DB9S) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C.2. Accessory Power Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C.3. IEEE-488 GPIB Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C.4. RS-232C Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C.5. Expansion Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
85
85
86
87
87
88
APPENDIX D. Model 398 Impedance Plots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
D.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
D.2. Plots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
vi
Model 283 User’s Manual
6DIHW\,QVWUXFWLRQVDQG6\PEROV
This manual contains up to three levels of safety instructions that must be observed in order to avoid personal
injury and/or damage to equipment or other property. These are:
DANGER
Indicates a hazard that could result in death or serious bodily harm if the safety instruction is not
observed.
WARNING
Indicates a hazard that could result in bodily harm if the safety instruction is not observed.
CAUTION
Indicates a hazard that could result in property damage if the safety instruction is not observed.
Please read all safety instructions carefully and make sure you understand them fully before attempting to use
this product.
&OHDQLQJ,QVWUXFWLRQV
WARNING Using this instrument in a manner not specified by the manufacturer may impair the protection
provided by the instrument.
To clean the instrument exterior:
Unplug the instrument from all voltage sources.
Remove loose dust on the outside of the instrument with a lint-free cloth.
Remove remaining dirt with a lint-free cloth dampened in a general-purpose detergent and water solution.
Do not use abrasive cleaners.
CAUTION
To prevent moisture inside of the instrument during external cleaning, use only enough
liquid to dampen the cloth or applicator.
Allow the instrument to dry before reconnecting the power cord.
vii
FCC NOTICE
This equipment generates, uses, and can radiate radio-frequency
energy and, if not installed and used in accordance with this
manual, may cause interference to radio communications. As
temporarily permitted by regulation, operation of this equipment in
a residential area is likely to cause interference, in which case the
user at his own facility will be required to take whatever measures
may be required to correct the interference.
viii
Model 283 User’s Manual
,1752'8&7,21
1.1. Overview
The Princeton Applied Research Model 283 Potentiostat/Galvanostat is a powerful and versatile
instrument for the electrochemistry researcher. It can be controlled either directly from its front
panel or from a personal computer.
This instrument uses the latest design advances to provide high performance, ease of use, and
great versatility in electrochemical measurements. Its ±80 V compliance and ±100 mA output
capability allow rapid and accurate potential or current control in virtually any electrochemical
cell. Component selection, shielding, grounding, and circuit design are all carefully optimized for
minimum internal electronic noise, giving high sensitivity and a quiet output signal. Low-pass
filters virtually eliminate noise arising in the cell itself.
A high-performance current-to-voltage converter circuit is included for accurate, rapid, low-drift
current measurements, free of degradation from cell-cable resistance, capacitance, and
inductance. The new self-calibration in the Model 283 feature assures the accuracy of your data,
while BNC connectors conveniently placed on the front panel make all signals of interest
available for analog recording.
1.2. Controlling the Model 283
1.2.1. Front-Panel Control
You can conduct a wide variety of static or scanning experiments directly from the front panel of
the Model 283. Its controls have been ergonomically designed for ease of use and maximum
flexibility. The large, convenient parameter input knob, pushbuttons, and alphanumeric liquid
crystal display streamline the process of setting up your experiment.
After the experiment begins, the display panel presents continuously updated information on its
progress, including the parameters in effect and the cell voltage and current. A simple touch of a
button implements such advanced features as automatic current ranging and current-interrupt iR
compensation.
1.2.2. Remote Computer Control
For even greater versatility, you can control the Model 283 from a personal computer via an
IEEE-488 (GPIB) or RS-232 interface. This enables you to take advantage of the
Electrochemical Command Set, a group of over 100 mnemonic software instructions that make it
easy to create your own experiments. The Electrochemical Command Set, which is built into the
Model 283's read-only memory, has been specifically developed for research electrochemistry,
dc corrosion measurements, and electrochemical impedance measurements. These commands
place unprecedented flexibility in the hands of the electro chemist. They provide:
Access to most Model 283 front-panel functions.
Control of all timing functions.
Application of pulse and staircase waveforms.
Automatic acquisition of data with or without current auto-ranging.
Data averaging in real-time.
Internal storage and arithmetic data manipulation on your lab computer.
1
These commands and all necessary instructions for operating the Model 283 from an external
computer are described in the separately bound Model 283 Command Set Handbook.
The Instruments HeadStart™ Creative Electrochemistry Software - included free with the Model
283 - provides a simple way to access the Electrochemical Command Set. HeadStart is easy to
use and runs on any IBM PC or fully compatible personal computer. To learn how to use it, refer
to the HeadStart instruction manual included with the Model 283.
The Model 283 is also completely compatible with the standard PARI electrochemical software.
So you can also run your experiments with any of our dedicated software packages, such as the
Model 270/250 Research Electrochemistry Software, the Model 352 Corrosion Measurement and
Analysis Software, or the Model 398 Impedance Software running on an IBM PC or fully
compatible computer connected to the Model 283.
When controlled by HeadStart or any of the standard PARI electrochemical software, the Model
283 can control the on/off status and speed of a Model 616 or 636 Rotating Electrode System or
send Purge, Stir, and Dispense signals to the Model 303A Static Mercury Drop Electrode.
The Model 283 is fully equipped to conduct experiments controlled from your computer. It
includes:
A 14-bit digital-to-analog convert for dc bias applications.
A 16-bit digital-to-analog converter for versatile waveform generation.
A 12-bit analog-to-digital converter to measure current and potential.
An on-board microprocessor to perform the experiment defined by the Command Set.
On-board memory to store the programmed parameters and data point values.
When the programmed experiment is finished, the data can be transferred to the computer for
plotting or further processing.
1.3. Operating Modes
1.3.1. Potentiostatic
In this mode, the Model 283 controls the potential at the working electrode with respect to the
reference electrode. The potential at the counter electrode is driven to the potential required
(consistent with the ±80 V compliance of the control amplifier) to establish the desired working
electrode potential. The range over which the working electrode potential can be controlled is
±10 V, of which ±8 V can be used in a single experiment.
1.3.2. Galvanostatic
In Galvanostatic operation, the Model 283 controls the current between the counter and working
electrodes at the specified traction of the selected current range (up to the maximum of two
times the current range). The counter electrode is driven to the potential required (consistent with
the ±80 V compliance of the control amplifier) to establish the desired cell current. The reference
electrode is not used in the control loop, but is usually used to measure the potential at some
point in the electrochemical cell.
2
Model 283 User’s Manual
1.4. About This Manual
This User's Guide provides details of the physical and electrical characteristics of the Model 283,
and describes how to operate it as a stand-alone instrument controlled from its front panel.
Instructions for operating the unit remotely from a personal computer or workstation, via either
the RS-232 or GPIB (IEEE-488) interface port, are given in the separately bound Model 283
Command Set Handbook. The HeadStart Creative Electrochemistry Software Instruction Manual
shows you how to use HeadStart.
The Model 283 Command Set Handbook gives, in addition to the command descriptions,
detailed explanations of GPIB (IEEE-488) and RS-232 communications and how to set the
communications parameters. It also includes an application note on waveform programming, one
of the most useful functions of the Model 283.
This User's Guide is organized into ten chapters and three appendices as follows.
Chapter 1: Simple overview of the instrument
Chapter 2: Important safety precautions for operating this instrument
Chapter 3: Installation and a simple rote checkout procedure
Chapter 4: Front-panel controls, connectors and indicator lights
Chapter 5: Back panel
Chapter 6: Operating considerations common to both potentiostatic and galvanostatic
operation as well as basic experiment parameters that seldom require changing.
Chapter 7: Potentiostatic experiments
Chapter 8: Galvanostatic experiments
Chapter 9: Circuit description
Chapter 10: Maintenance and Service
Appendix A: Specifications
Appendix B: Technical Reference
Appendix C: Connector Pinouts
Appendix D: Model 398 Impedance Plots
Chapter 1 — INTRODUCTION
3
4
Model 283 User’s Manual
6DIHW\&RQVLGHUDWLRQV
2.1. Overview
This instrument has been supplied in a safe condition. To ensure its continued safe operation,
please read the following sections.
2.2. Power Cord
For safe operation, the Model 283 must be electrically connected to earth ground through a
suitable protective conductor. This connection is made via the earth ground prong of the Model
283's power cord plug. Thus the power cord plug must be inserted into a socket outlet provided
with the required earth ground contact. The protective action must not be defeated by the use of
an extension cord without a protective conductor, by use of an “adapter” that doesn't maintain
earth ground continuity, or by any other means.
Wherever possible, the instrument is furnished with a power cord plug that is compatible with the
type of power socket in use where the instrument will be operated. If you have to provide a
power cord, it should be an approved type with a standard IEC connector at one end for
connection to the Model 283.
Warning! If it is necessary to replace the power cord or the power cord plug, the
replacement cord or plug must have the same polarity as the original Otherwise a safety
hazard from electrical shock which could result in personnel injury or death, might result.
The wires in the power cord supplied by PARI are color-coded to denote polarity. Whatever the
actual plug configuration, the black wire should be the line or active conductor (also called "live"
or "hot'), the white wire should be neutral, and the green wire should be earth ground.
2.3. Line Voltage
2.3.1. Introduction
Before plugging in the power cord, make sure that the Model 283 is set to the voltage of the ac
power supply. The Model 283 is equipped with a tapped power transformer that allows operation
over a wide range of possible line voltages. The transformer configuration is determined by the
rear-panel Corcom power-input module, as explained in the following paragraphs.
Caution! The Model 283 may be damaged if it is set for operation from 110 or 120 V and
operated from a source of 220 V or 240 V power.
2.3.2. Confirming the Line Voltage Setting
Look through the clear plastic cover on the ac power input module, located at the lower-right
corner of the rear panel. Behind the plastic cover is the power line fuse and a small PC board.
The line voltage for which the instrument is set is printed on the PC board in a position that is
visible through the plastic cover.
If the Model 283 isn't set for the voltage available at your site, make the necessary changes in
the selected voltage before connecting the 283 to a power source. Section 2.3.3, which follows,
explains how this is done.
5
Fig. 2. Corcom Module.
2.3.3. Line Voltage Selection
To change selected voltage: disconnect the power cord; open cover of the power entry module
on rear of the instrument using a small blade screwdriver or similar tool. Insert the tool into the
voltage selection slot and remove wheel from unit; select desired voltage; replace wheel into unit
and close cover, making sure the selected voltage appears in connector window. See Fig. 2.
2.3.4. Changing Fuse
To change the fuse: disconnect the power cord; open cover of the power entry module on rear of
the instrument using a small blade screwdriver or similar tool. Remove fuse holder and replace
fuse. If changing to the metric type fuse, change the fuse holder to the metric version and insert
the proper fuse as specified in the manual. After replacing the fuse/fuse holder, insert the fuse
holder into the unit and close cover. See Fig. 2.
2.4. Cell Safety
Warning! With a compliance of 80 V and the ability to deliver currents as high as 100 mA,
the Model 283 is capable of delivering dangerous, even lethal, electrical shocks. Users must
always exercise caution when connecting the cell cables or performing any operation that
brings them into contact with cell potentials. Moreover, it is absolutely essential that the frontpanel CELL SAFETY switch be in the OFF position whenever operations are being
performed Mat can bring the user into contact with cell potentials. The front-panel CELL ON
key (small pushbutton just below the Cell On indicator) can be used to turn the cell
connections on and off when the CELL SAFETY switch is ON. However, the CELL ON key
should NOT be relied on for operator safety.
2.5. Defects and Abnormal Stresses
Warning! If your instrument has been damaged, its protective grounding may not work. Do
not operate damaged equipment! Tag it to indicate to a potential user that it is unsafe to
operate.
6
Model 283 User’s Manual
The ground protection is likely to be impaired if, for example, the instrument:
Shows visible damage.
Fails to perform the intended measurement.
Has been subjected to prolonged storage under unfavorable conditions.
Has been subjected to severe transport stresses.
The instrument should not be used until its safety has been verified by qualified service
personnel.
2.6. Ventilation
To maintain a safe operating temperature, it is necessary to allow some free space (minimum
10 cm) at the sides and rear of the instrument so that adequate air circulation can occur.
Moreover, there must be adequate circulation between the space at the bottom and back of the
instrument and the general laboratory circulation to allow effective cooling. In a typical
installation, these requirements are satisfied with a large safety margin. If the Model 283 is
operated in an enclosed space, some additional effort to assure adequate ventilation may be
required.
Chapter 2 — SAFETY CONSIDERATIONS
7
8
Model 283 User’s Manual
,QVWDOODWLRQ,QLWLDO&KHFNV
3.1. Introduction
This chapter guides you through installing the Model 283 and running through a simple rote test
procedure using the internal 10 k dc dummy cell. This demonstrates whether the 283 is
functioning properly as well as helping acquaint you with the operation of the instrument. No
special test equipment is required. The checks are adequate for determining that the instrument
has arrived in good working order and is functioning normally. They are not intended to
demonstrate that the instrument meets specifications. Each Model 283 receives a careful
checkout before leaving the factory and, if no shipping damage has occurred, will perform within
the limits of the specifications.
If any problems are encountered in carrying out these checks, contact the factory or the factoryauthorized representative in your area for aid.
The check-out procedure in this chapter should not be construed as detailed operating
instructions. Subsequent chapters discuss in detail the considerations germane to making
successful measurements.
3.2. Installation
3.2.1. Inspection
Inspect your Model 283 for shipping damage. If any is noted, immediately notify PARI and file a
claim with the carrier. Save the shipping container for inspection by the carrier.
Warning! If you have received a damaged instrument, its protective grounding may not work.
Do not operate damaged equipment! Tag it to indicate to a potential user that it is unsafe to
operate.
3.2.2. Power Cord Plug
The rear panel is equipped with a standard IEC 320 socket and a suitable power cord is supplied
with the instrument.
3.2.3. Location
Before setting up and connecting your instrument, give some thought to finding a safe and
convenient location for it. The Model 283 can be operated on almost any laboratory bench. With
an ambient temperature range of 0(C to 45(C, it is highly tolerant to environmental variables,
needing only to be protected from exposure to corrosive agents and adverse weather conditions.
Note: Review the discussion of ventilation in Section 2.6, Ventilation, of Chapter 2, Safety
Considerations.
3.2.4. Power Voltage Selection and Line Fuses
Before plugging in the power cord, ensure that the Model 283 is set to the voltage of the ac
power supply.
Note: Review the discussion of line voltage selection in Section 2.3, Line Voltage, of Chapter 2,
Safety Considerations.
9
3.3. Initial Checks Procedure
3.3.1. Introduction
The following steps program the Model 283 to do a controlled-potential experiment on the
internal 10 k dummy cell resistor. A scan starting at 0 V, advancing to 1 V, and then returning
to 0 V will be applied. The current in the resistor will track this voltage, starting at zero,
increasing in the negative direction to -100 µA, and then decreasing to zero again. A voltage
corresponding to this current will appear at the I MONITOR connector. The current through the
resistor and the voltage across it will be displayed throughout the experiment on the LCD panel.
Note: Analog components cannot be made to exhibit exactly their rated values, especially
under varying temperature conditions. Thus analog components have tolerance ratings that
specify acceptable ranges above and below their nominal values. The 10 k dummy cell
resistor, for example, has a very tight 0.01% tolerance, which means that its actual
resistance in the circuit could be anywhere between 9,999 and 10,001 . Also, residual drift
or noise in the Model 283 itself can contribute a small additional deviation in both the current
and potential indications. As a result of these uncertainty factors, the current indications on
the LCD panel may vary a bit from the values stated in this procedure.
3.3.2. Connections
1. Before proceeding to the dummy cell connections, be sure that the Cell Safety switch,
located near the bottom of the front panel adjacent to the A/D Input 1 connector, is in the
OFF position. Note that this is a push-button toggle switch that changes state each time it is
pressed. The state, ON or OFF is always displayed on the front of the switch.
Note: Review Section 2.4, Cell Safety, in Chapter 2, Safety Considerations.
2. Identify the four cell cables supplied with the instrument, as follows.
Counter Electrode cable: Coaxial cable with BNC connector at one end and a red pin jack
and alligator clip at the other end.
Working Electrode cable: Coaxial cable with BNC connector at one end and a green pin
jack and alligator clip at the other end.
Reference Electrode cable: Large diameter cable characterized by a gray grooved grip and
10 pin connector at one end and terminated in a pod having a white pin jack at the front and
a red one at the back.
Sense cable: Large diameter cable characterized by a gray grooved grip and 10 pin
connector at one end and terminated in a pod having a gray pin jack at the front and a green
one at the back.
3. Connect the four cables to their corresponding front-panel connectors as follows.
Counter Electrode cable to the Counter front-panel connector.
Working Electrode cable to the Working front-panel connector.
Reference Electrode cable to the Reference front-panel connector. Grasp the connector on
the cell cable by the grooved grip, turn it so the red dot aligns with the red mark on the CELL
connector, and press it into place. To disconnect the cell cable connector, grasp the grooved
grip and pull straight out.
10
Model 283 User’s Manual
Sense cable to the Sense front-panel connector. Grasp the connector on the cell cable by
the grooved grip, turn A so the red dot aligns with the red mark on the CELL connector, and
press it into place. To disconnect the cell cable connector, grasp the grooved grip and pull
straight out.
4. Note the DC Dummy Cell pin jacks, located towards the lower left of the panel. The cell
cables should be connected to the internal dc dummy cell as shown in Fig. 3.
Fig. 3. Initial Checks Cable Connections.
a. Using a short clip-lead terminated in a pin jack at each end, connect one of the pin jacks on
the pod at the end of the Reference Electrode cable to the left-hand DC Dummy pin jack.
b. Connect the pin jack at the end of the Counter Electrode cable to the other pin jack on the
Reference Electrode cable pod.
c.
Using a short clip-lead terminated in a pin jack at each end, connect one of the pin jacks on
the pod at the end of the Sense cable to the right-hand DC Dummy Cell pin jack.
d. Connect the pin jack at the end of the Working Electrode cable to the other pin jack on the
Sense cable pod.
3.3.3. Power-Up and Cell Safety
Plug the power cord into a convenient source of ac power. Then press the Power pushbutton,
located at the lower left of the front panel, to turn on the power to the 283.
Press the Cell Safety switch to reverse its state. It should display the word ON.
3.3.4. Procedure
1. Press the MODE key, located below the LCD display, until the [Potentiostatic Scan] menu is
displayed on the LCD display. The POTENTIOSTAT indicator should be lit, indicating that
the Model 283 is in the controlled-potential mode.
Chapter 3 — INSTALLATION & INITIAL CHECKS
11
2. Press the PREV or NEXT PARAMETER key until E INIT = appears on the third line of the
LCD display. Then, turn the VALUE knob until E INIT = 0.000V is displayed. This enters 0 V
as the programmed starting potential for the scan to be performed.
As you would expect, the faster you turn the VALUE knob the faster the parameter value
changes. But note that the relationship between knob speed and value change does not
remain linear. Above a certain knob speed the processor "shifts gears" and changes to a
higher ratio of parameter change to knob speed. This allows you to make large changes in
the value of a parameter by spinning the knob rapidly.
3. Press the NEXT PARAMETER key once. "E MID =" should appear on the third line of the
LCD display. Then, turn the VALUE knob until E MID = 1.000V is displayed. This establishes
1.000 V as the scan vertex potential.
4. Press the NEXT PARAMETER key again. "E FINAL =" should appear on the third line of the
LCD display. Then, turn the VALUE knob until E FINAL = 0.000V is displayed. This
establishes the scan-end potential at 0 V (which was also the starting potential).
5. Press the NEXT PARAMETER key again. “T INIT =" should appear on the third line of the
LCD display. Then, turn the VALUE knob until T INIT = 10.0s is displayed. This enters 10 s
as the time for which E INIT (0 V) will be applied before beginning the scan.
6. Press the NEXT PARAMETER key again. “T MID =" should appear on the third line of the
LCD display. Then, turn the VALUE knob until T MID = 10.0s is displayed. This establishes
10 seconds as the time for which the mid or vertex potential (E MID) will be applied.
7. Press the NEXT PARAMETER key again. "T FINAL =" should appear on the third line of the
LCD display. Then, turn the VALUE knob until T FINAL = 10.0s is displayed. This establishes
10 seconds as the time for which the scan-end potential (E FINAL) will be applied.
8. Press the NEXT PARAMETER key again. "SCAN RATE =" should appear on the third line of
the LCD display. Then, turn the VALUE knob until SCAN RATE = 20.0 mV/s is displayed.
(The scan rate is the rate of change of the applied potential.)
9. Press the NEXT PARAMETER key again. "CYCLES =" should appear on the third line of the
LCD display. Then, turn the VALUE knob until CYCLES = FULL is displayed. This programs
the Model 283 to scan the potential applied at the working electrode between E INIT, E MID,
and E FINAL for one complete cycle, with the scan rate and time delays you have specified,
and then end the experiment. FULL CYCLE is defined in Appendix B under Cycle Control.
10. Press the NEXT PARAMETER key again. "CELL @ END =" should appear on the third line
of the LCD display. Then, turn the VALUE knob until CELL @ END = E FINAL is displayed.
This will cause the cell to remain at the scan-end potential (E FINAL) after the scan is
complete.
11. The current auto-range feature should be turned off for this test. Make sure the AUTO
indicator at the lower right side of the front panel is not lit. If it is, press the AUTO pushbutton
to turn off current auto-ranging.
12. Press the [] or [] key above the AUTO pushbutton as necessary to light the 100 µA fullscale current range indicator.
13. Press the CELL ON key to enable the cell connector. The CELL ON indicator just above it
should light, showing that the cell is connected.
12
Model 283 User’s Manual
The Model 283 is now ready to run the experiment, using its internal dummy cell resistor as
a substitute for an actual cell. The programmed sequence will be initiated in the following
step.
14. Press “Start”. (Note that on this menu the F3 key now is assigned the "Star” function.) The
following should be observed.
a. Once start has been initiated, F3's function is reassigned as "Stop". You can press F3 to
stop your experiment at any time. (F3 will be assigned the “Star” function again, and you
may press it at any time to restart the checkout sequence.)
b. The initial potential (0 V) and the resulting current (0 µA) are indicated on the second line
of the LCD display.
Note: As previously mentioned, there may be some small deviation from the nominal
value.
c. After the programmed initial delay interval (T INIT = 10.0s), the scan will begin and the
displayed potential and current will begin to increase. The potential will start at 0 V
(E INIT) and increase gradually to 1 V (E MID). It will remain at 1 V for 10 seconds (T
MID). Then, it will gradually decrease to 0 V (E FINAL). It will remain at 0 V for 10 more
seconds (T FINAL).
The current will track this voltage, starting at zero, increasing in the negative direction to
-100 µA, and then decreasing to zero again.
15. Press the CELL ON key once to disconnect the cell. The associated indicator light should
extinguish.
16. Press the CELL SAFETY switch, re-establishing the secure mode in which the CELL ON key
will not complete the cell connections.
17. Press the Model 283 POWER switch to turn off power to the unit. The indicator lights will
extinguish and the LCD panel will blank.
This completes the initial checks. If the Model 283 behaved as indicated above, you can be
reasonably confident that all its circuits are functioning normally.
Chapter 3 — INSTALLATION & INITIAL CHECKS
13
14
Model 283 User’s Manual
)URQW3DQHO
4.1. Introduction
This chapter serves as a reference to the front and rear panels. (Operation is discussed in
subsequent chapters) In that regard, Fig. 5 which shows the front panel with identifying callouts,
provides a convenient but brief overview. The remainder of the chapter discusses the panel
features in more detail. To as great a degree as possible the discussion topics track the panelfeature groupings as delineated on the front panel.
4.2. Cell Group
4.2.1. Introduction
As illustrated in Fig. 4, there are four Cell connectors,
COUNTER, WORKING, REFERENCE, and SENSE.
Cables are supplied with the Model 283 for making the
connections between these connectors and the cell. The
Cell On key and Overload indicators are also located in
this area. All are discussed in the following paragraphs.
4.2.2. COUNTER
The COUNTER BNC connector supplies the output of
the Power Amplifier to the front panel. The Counter
Electrode cable (BNC cable terminated in red pin jack
and alligator clip) is used to make the connection to the
Counter Electrode at the cell. Fig. 7 illustrates the
connections for the cell cables in potentiostatic
operation. As indicated, the Counter Electrode cable
connects directly to the Counter Electrode in standard
three-electrode operation. Also shown are the
Fig. 4. Cell Group.
connections for two-electrode operation, in which the
Counter Electrode and Reference Electrode are
jumpered together. In that configuration the Counter Electrode cable connects to one of the two
pin jacks on the Reference Cable pod, the other pin jack being connected to the Reference
Electrode of the cell, and to the Counter Electrode via the jumper already mentioned (jumper to
be supplied by user).
Fig. 8 shows the cell connections for galvanostatic operation. As indicated, the Counter
Electrode cable connects directly to the Counter Electrode at the cell.
15
Fig. 5. Model 283 Front Panel.
A: CELL ON key: Turns cell connections ON and OFF as indicated by
CELL ON indicator. CELL SAFETY switch must be ON to activate cell.
H: CONTRAST adjustment: Sets display contrast level.
I: DISPLAY: Indicates instrument status and parameters.
B: WORKING connector: Working Electrode cable (color-coded
green) connects here.
J: VALUE knob: Sets parameter values.
C: CELL ON indicator: Lights when cell is connected.
K: CURRENT range indicators: Indicate selected Current Range.
D: SENSE connector: Sense cable (color-coded gray) connects here.
L: CURRENT range pushbuttons: Under manual control, allow current
range to be selected.
E: COUNTER connector: Counter Electrode cable (color-coded red)
connects here.
F: REFERENCE connector: Reference Electrode cable (color-coded
white) connects here.
G: OVERLOAD indicators: I overload if current exceeds two times
selected range. E overload if cell control loop is out of control.
M: AUTO key. Selects automatic or manual current ranging.
N: AUTO indicator: Lights when auto current ranging is selected.
0: PARAMETER PREV & NEXT keys: Select next available or
previous available parameter for display.
P: I MONITOR: Voltage analog of cell current; 1 V = f.s.
16
Model 283 User’s Manual
Q. E MONITOR: Working Electrode potential (vs Reference
Electrode); corrected for RU.
Y: MODE indicators: Indicate whether instrument is in potentiostat or
galvanostat mode.
R: MUX: Ac coupled analog of potential or current as selected by MIE
command.
Z: Allows selection of potentiostat or galvanostat operation.
S: OUTPUT: Voltage set by SETOUT2 command provided at this
connector.
T: EXT IN: Externally derived control signal can be applied here.
Associated indicator lights when input is “on”.
U: D/A OUTPUT: Voltage set by SETOUT command provided at this
connector.
AA: A/D INPUT 2: Auxiliary input signal applied here and selected by
AUXSEL 1 command can be acquired during scan.
BB: A/D INPUT 1: Auxiliary input signal applied here and selected by
AUXSEL 0 command can be acquired during scan.
CC: CELL SAFETY switch: Cell cannot be turned an when this switch
is set to OFF.
DD: GND: Convenient source of ground potential.
V: INTERFACE indicators: Report communications status during
control from computer via IEEE488 GPIB bus.
W: SYSTEM key: Allows access to the [System Interface] menu from
any potentiostat or galvanostat menu.
X: F1 thru F5 keys: Soft control keys whose functions change
according to display status. Functions are indicated on display.
Chapter 4 — FRONT PANEL
EE: DC DUMMY CELL and AC DUMMY CELL: Internal dummy cells
can be accessed via these pin-jacks.
FF: POWER switch: Ac power to instrument controlled by this switch.
GG: POWER indicator: Lights when instrument is powered.
17
Fig. 7. Potentiostat Mode Cell Connections.
18
Model 283 User’s Manual
Fig. 8. Galvanostat Mode Cell Connections.
4.2.3. WORKING
This connector's function depends on the operating mode. In potentiostat mode (Fig. 7), the
working-electrode current is applied to the input of the I/E converter. In galvanostat mode
(Fig. 8), this connector completes the working-electrode-current feedback path to the summing
junction of the power amplifier. In both modes the Working Electrode cable (BNC cable
terminated in a green pin jack and an alligator clip) connects to one of the pin jacks on the Sense
Cable pod. The other pin jack of the Sense Cable pod connects directly to the Working Electrode
at the cell by the shortest possible path. There are no special working-electrode considerations
for two-electrode potentiostatic operation.
4.2.4. REFERENCE
The path from the Reference Electrode to one of the two inputs of the differential electrometer is
completed via this connector with the Reference Electrode cable (heavy cable with gray grip at
the connector end and, at the other end, a pod having a white pin jack at the front and a red one
at the back). As shown in Figs. 7 and 8, the pin-jack connections at the pod depend on the
configuration. In standard three-electrode operation as a potentiostat, one of the pin jacks at the
pod connects directly to the Reference Electrode by the shortest possible path and the second
pin jack isn't used. In two-electrode operation, the second pin jack is used for the Counter
Electrode cable connection. When operating as a galvanostat, the Reference cable can be
connected as shown to monitor the potential, keeping in mind that the cell current is controlled in
galvanostatic operation and the potential reading is simply ancillary information.
4.2.5. SENSE
The Sense connector, as shown in Figs. 7 and 8, completes the sense path to the Working
Electrode via the Sense cable (heavy cable with gray grip at the connector end and, at the other
Chapter 4 — FRONT PANEL
19
end, a pod having a gray pin jack at the front and a green one at the back). As indicated in the
figures, one of the Sense Cable pin jacks on the pod connects to the Working Electrode of the
cell by the shortest possible path. The Working Electrode cable plugs into the other pin jack.
4.2.6. OVERLOAD Indicators
The I OVERLOAD indicator lights if the working electrode current exceeds two times the fullscale current range. This does not mean that the cell control loop is out of control. For example,
suppose the Model 283 were programmed to establish a potential of +0.752 V, and that under
the established conditions, a cell current of 0.5 mA occurred. If the current range were 1 µA, 10
µA, or 100 µA, the current monitoring circuits would be driven to the limit and the I OVERLOAD
indicator would light, even though the cell would still be controlled at +0.752 V.
Unlike with the I OVERLOAD indicator, a lighted E OVERLOAD indicator always means that the
cell control loop is out of control. That is, the control amplifier has reached its maximum
compliance Voltage of ±80 V, and the potential of the working electrode with respect to the
reference electrode is not as programmed. This could result from a connection error (open cell
connection), an electrode problem, or an unacceptably high solution resistance.
4.2.7. CELL Indicator
This indicator lights whenever the internal cell relay is closed. The cell relay is controlled either
by the CELL ON key or by the CELL command sent from an attached computer.
4.2.8. CELL ON Key
The CELL ON key controls the cell relay, which determines whether the control amplifier is
connected to the cell. Note: The CELL SAFETY switch must set to ON before the Cell On key
can activate the cell connections. When the CELL ON key is off (CELL indicator not illuminated),
the control amplifier is disconnected from the cell and there is zero cell current, allowing the cell
connections to be made safely. When the CELL ON key is on (CELL indicator lit), the control
amplifier is connected to the cell.
The cell relay also can be controlled by a software command from an attached computer.
The cell control loop remains controlled even when the cell isn't on. Having the cell off does not
cause an overload condition.
4.3. Display/Control Group
4.3.1. Introduction
In local operation, the 283 is controlled and the experiment status monitored using this group. In
addition to the LCD display, the group includes the soft-keys F1 through F5, the MODE and
SYSTEM keys, the VALUE knob, used to set parameter values, and the two Parameter keys,
PREV and NEXT. Fig. 9 is provided as a convenient reference for the Display/Control Group
discussions that follow.
20
Model 283 User’s Manual
Fig. 9. Display/Control Group.
4.3.2. Mode key
This key selects the basic operating mode of the Model 283: POTENTIOSTAT or
GALVANOSTAT - and selects either a discrete step or a gradual scan between applied voltage
or current levels. An indicator lamp lights to show whether the POTENTIOSTAT or
GALVANOSTAT mode has been selected, and the appropriate menu screen appears on the LCD
panel. Fig. 10 shows the sequence in which the experiment menu screens appear when you
repeatedly press the MODE key.
Note that you cannot switch between potentiostatic and galvanostatic operation during an
experiment, as this would require basic changes in the entire system configuration. Thus, when
the cell is on, you cannot change between potentiostatic and galvanostatic menus. If the
[Galvanostatic Step] menu is displayed, pressing the MODE key will switch to the [Galvanostat]
menu. Similarly, if the [Potentiostatic Step] menu is displayed, pressing the MODE key will
switch to the [Potentiostat] menu.
The MODE key also can be used to move from the [System Default] menu screen on the LCD
display to one of the potentiostat or galvanostat menus (see Fig. 11). The MODE key is disabled
during remote-control operation.
4.3.3. System key
In local control, the SYSTEM pushbutton allows you to access the [System Interface] menu
screen on the LCD panel from any potentiostat or galvanostat menu (see Fig. 11). It also moves
you from the [System Interface] menu to the [System Default] menu and from the [System
Default] menu to a potentiostat or galvanostat menu.
Chapter 4 — FRONT PANEL
21
Fig. 10. Order Of Menu Screens That Appear When
You Press The Mode Key From Any Potentiostatic or
Galvanostatic Screen.
Fig. 11. Moving Among The System, Function, &
Potentiostatic or Galvanostatic Screens.
4.3.4. LCD Display
The four-line liquid crystal display provides continuous information on the experiment in
progress, including the parameters set and the voltage and current measurements being taken.
The information shown depends on which of the several available menu screens is displayed. In
local control, the MODE and SYSTEM keys above the display allow you to cycle through the
screens (see Chapters 6, 7 & 8).
In the event of a system malfunction, the LCD panel will display an error message describing the
problem and sometimes directing the operator to take the required action. For an explanation of
these error messages, refer to Section 6.1 1. Remote-control software error messages are
explained in the Model 283 Command Set Handbook.
22
Model 283 User’s Manual
4.3.5. F1 Through F5 Function keys
In local control (when you are controlling the Model 283 from its front panel), these "soft" keys
perform various actions before and during an experiment. You use them to start your experiment
and control its progress. You can also use them to recalibrate the instrument (see Section 6.9)
and reset the experiment parameters to their default values (Section 6.8).
The function assigned to each key is displayed on the bottom line of the LCD panel. These
functions may change if you switch to another menu screen.
When the Model 283 is under control of an external computer, F1 through F4 have no functions
assigned. Pressing F5 will return you to local control and bring up either the [Potentiostat] or
[Galvanostat] menu screen.
4.3.6. Value knob
In local control, this knob sets the value of any experiment parameter selected with the PREV
and NEXT PARAMETER keys. The parameter being set is displayed on the third line of the LCD
display.
The VALUE knob provides tactile feedback and has a speed sensing feature to make parameter
setting easy and intuitive. As you would expect, the faster you turn the knob the faster the
parameter value changes. But note that the relationship between knob speed and value change
does not remain linear. Above a certain knob speed the processor "shifts gears" and changes to
a higher ratio of parameter change to knob speed. This allows you to make large changes in the
value of a parameter by spinning the knob rapidly.
To prevent someone from inadvertently changing the value of a parameter by brushing against
the VALUE knob, you can disable the knob after using it. You can specify the period of time it
wafts after its last use before becoming inactive (the “timeout” period). The Knob Timeout
parameter is set from the [System Interface] menu screen. See Appendix B for a more detailed
explanation of the timeout parameter and how to set it.
4.3.7. Prev and Next Parameter keys
In local control, these keys allow you scroll through the available parameters one at a time. Next
moves forward through the list, selecting and displaying the next available parameter each time
it is pressed. Prev moves backwards through the list, selecting and displaying the last available
parameter each time it is pressed. The selected parameter is always displayed on the third line
of the LCD panel and, while displayed, its value can be changed with the VALUE knob.
4.4. Interface Group
This group contains three indicators that have
significance during GPIB communications and that
can be helpful in program development. The function
of each as follows.
Fig. 12. Interface Group.
TALK: Means that the 283 has data ready to send to the computer. This indicator goes out when
all of the data has been transferred.
LISTEN: Means that the 283 has detected the first character of a transmission from the
computer. This indicator extinguishes when the terminator marking the end of the transmission is
detected.
ERROR: Indicates that a communications error has occurred.
Chapter 4 — FRONT PANEL
23
4.5. Current Range Group
4.5.1. Introduction
This group allows you to select automatic or manual current ranging. If manual current ranging is
selected, it additionally allows you to select the current range.
4.5.2. Full-Scale Current Range Indicators, 100 mA through 1 nA
These indicator lamps monitor the Model 283's full-scale current range.
One of the nine available current ranges is always selected. A cell
current equal to the selected current range gives 1 V at the I MONITOR
connector.
In local control, the full-scale current range can be selected either
manually by the operator or automatically by the Model 283. In the
Manual mode, the range is selected with the arrow keys under the
indicator lamps. The key moves the selection upwards through the
available ranges. The key moves it downwards.
4.5.3. key
In the Manual current ranging mode (under local control), this key is
used to increase the full-scale current range of the Model 283. Pressing
this key steps the full-scale current range to the next higher range
available. The current range set is shown by illumination of the
corresponding indicator lamp. This key has no effect when AUTO
current ranging is on.
4.5.4. key
In the Manual current ranging mode (under local control), this key is
used to decrease the full-scale current range of the Model 283.
Pressing this key steps the full-scale current range to the next lower
range available. The current range set is shown by illumination of the
corresponding indicator lamp. This key has no effect when AUTO
current ranging is on.
4.5.5. AUTO Switch and Indicator
Fig. 13. Current Range
Group.
In the Potentiostat mode (local control), the AUTO switch is used to
select manual or automatic adjustment of the current range. Pushing the switch toggles between
the auto and manual modes. The AUTO Indicator lamp is lit when AUTO is selected.
Note that automatic current ranging is restricted to operation in the Potentiostat mode, with
100 nA being the most sensitive range the Model 283 can automatically select. Auto-ranging
cannot be selected in the Galvanostat mode.
In the AUTO current range mode, the Model 283 automatically seeks the full- scale current range
that causes the I MONITOR potential to be between 15% and 190% of full scale; that is, between
150 mV and 1.9 V. If cell current is less than 150 nA, the 100 nA range will be selected. If the
instrument is on the 10 mA range and cell current is greater than 19 mA, the 100 mA range will
be selected. This process occurs after each point is acquired, with the constraint that it can only
change one range at a time. Data could be lost if the data amplitude is changing faster than it
can be tracked by the auto-ranging function.
24
Model 283 User’s Manual
You can set a limit to the automatic current ranging by adjusting the I AUTO LIMIT parameter on
the [System Default] menu (see Current Range, Full Scale in Appendix B). The full-scale
current range will not go below the I AUTO LIMIT you set.
The I/E Filter (if selected) can cause unpredictable effects on your experiment if AUTO current
ranging is in use. If I/E FILTER = ON is selected (from the [System Default] menu screen), we
recommend manual current ranging. For additional information see Filters in Appendix B.
4.6. BNC Connectors
Fig. 14. BNC Connectors.
4.6.1. Introduction
In addition to the Counter and Working BNC connectors in the Cell Group, there is a row of eight
BNC connectors near the lower edge of the instrument that provide a variety of control and
monitoring functions as follows.
4.6.2. EXT IN
This BNC connector has two separate but similar functions: External Input and Oscillator Input.
The main difference between these functions is that, in the OSC IN mode, the gain of the applied
signal can be scaled up or down, while the EXT INPUT mode always applies unity gain to the
input signal.
This connector can be made active (turned on) or inactive either with the front panel controls or
by software commands from an external computer. From the front panel, it can be controlled
with either the EXT INPUT or the OSC IN setting on the [System Default] menu (see "Adding an
External Signal" in Section 6.13). Remote control from an attached computer is described in the
Model 283 Command Set Handbook. Note that both EXT INPUT and OSC IN cannot be set to
ON at the same time.
When this connector is active (associated indicator lighted), an analog control voltage applied to
it will be summed with the output of the digital-to-analog converters (DACs), which are set at the
front panel or from an attached PC. The control signals could be generated by, for example, an
PARI Model 175 Universal Programmer to provide rapid scanning and true analog cyclic
voltammetry. Other waveform generators, a lock-in amplifier, or a frequency response analyzer
could also be used.
In potentiostatic operation, all of the control potentials add algebraically. Fig. 25 in Chapter 9
shows the circuit configuration for potentiostatic operation. For example, if the voltage applied to
EXT INPUT is +0.5 V, at a time when a potential of +0.5 V is programmed in the instrument, the
net potential applied will be +1.0 V, and the working electrode would be controlled at +1.0 V with
respect to the reference electrode. (This assumes, of course, that the applied signal is not scaled
by selecting the OSC IN mode.) A positive applied potential will make the current tend to be
more anodic. A negative applied potential will make the current tend to be more cathodic. In
galvanostatic operation, making the applied potential more positive by any means except
applying a potential to the EXT INPUT connector will tend to make the cell current more
Chapter 4 — FRONT PANEL
25
cathodic. Making the applied potential more negative will tend to make the current more anodic.
This sense is reversed at the EXT INPUT connector. There, making the input more positive will
make the cell current more anodic (more negative will make the cell current more cathodic).
Fig. 26 shows the circuit configuration for galvanostatic operation.
In potentiostat operation, the maximum voltage that can be safely applied to the connector is
±10 V in the EXT INPUT mode and ±5 V in the OSC IN mode. In galvanostat operation, the safe
range in either mode is -2 V to +2 V (corresponding to ±2 times the full-scale current). The input
impedance at the connector is 1 M.
4.6.3. E MONITOR
This dc-coupled BNC connector can be used to monitor the polarity and amplitude of the working
electrode potential versus the reference electrode in the test cell. It can be used to drive the Xaxis of a pen recorder or oscilloscope. If positive feedback or current interrupt iR compensation
is enabled, the potential at the E MONITOR is corrected for uncompensated resistance (RU). The
output impedance is 50 .
4.6.4. I MONITOR
The potential at this dc-coupled connector represents the ratio of cell current to full-scale current
at the current range selected, with 1 volt representing unity or 100% of full-scale current.
For example, with the 10 µA full-scale range selected, 0.5 V at the I MONITOR connector
indicates that cell current is one half of full scale, or 5.0 µA. Or, if the 100 µA range is selected,
1.25 V at I MONITOR would indicate that the cell current is 125% of full scale, or 125 µA.
Although the analog-to-digital conversion is limited to two times full scale, the I MONITOR output
is linear to ±10 V, allowing large current spikes to be faithfully measured.
The polarity of the potential at the I MONITOR connector is the same as the polarity of the cell
current. On the 1 mA current range, for example, a current level of -1 mA will give -1 V at the I
MONITOR connector, representing an anodic or reducing current at the working electrode. This
connector can be used to drive the Y-axis of a pen recorder or oscilloscope. The output
impedance is 50 .
4.6.5. MUX
When the Model 263A is operated remotely from an external computer, this ac-coupled
connector (output impedance 50 ) can be used to monitor either cell current or cell voltage (as
determined by the MIE command). The default is cell current. The MUX connector cannot be
controlled from the front panel of the Model 283. Thus, under local control, the connector can
monitor current only. This connector is used mainly with PARI electrochemical impedance
systems.
When the instrument is monitoring cell current, the potential at this connector is the same as that
at the I MONITOR connector, except that any dc component of the signal is blocked by the ac
coupling. As with the I MONITOR connector, the potential represents the ratio of test cell current
to full-scale current at the current range selected, with 1 volt representing unity or 100% of fullscale current. Again, currents as high as 2 x full scale can be accommodated.
When the instrument is monitoring cell potential, the signal at this connector is the same as that
at the E MONITOR connector, except that any dc component of the signal is blocked by the ac
coupling. The connector is used to monitor the polarity and amplitude of the working electrode
potential versus the reference electrode in the test cell. The output range is ± 10 V. If positive
feedback or current interrupt iR compensation is enabled, the potential at the connector is
corrected for uncompensated resistance (RU).
26
Model 283 User’s Manual
4.6.6. A/D INPUT I & A/D INPUT 2
Allows an auxiliary signal applied to either of these connectors to be applied to an A/D converter
and acquired during data acquisition. A multiplexer controlled by the AUXSEL 0 & 1 command
determines which of the two is selected. Additionally, it is necessary that the SIE parameter be
appropriately set in order for the selected auxiliary signal to be acquired during data acquisition.
The input impedance at both connectors is 100 k. Note: The manner in which signals applied
to these inputs are processed cannot be controlled from the front panel.
4.6.7. OUTPUT
The output of a 12-bit DAC controlled by the SETOUT2 command is provided at this output,
making available a precise dc voltage (range ±2 V; impedance 300 ). Possible uses include
speed control of the Model 616 or 636 if applied to the INPUT connector of either instrument.
Note that this output cannot be controlled from the front panel.
4.6.8. D/A OUTPUT
The output of a 12-bit DAC controlled by the SETOUT command is provided at this output,
making available a precise dc voltage (range ±2 V; impedance 300 ). Possible uses include
speed control of the Model 616 or 636 if applied to the INPUT connector of either instrument.
Note that this output cannot be controlled from the front panel.
4.7. Gnd Connector
The GND connector provides a convenient source of ground potential at
the front panel. It can be used in a number of ways. Although it is not
required for routine potentiostat or galvanostat operation, it is available if
needed for a special purpose, such as supplying ground to a shield-screen
surrounding a cell.
An exception is in making galvanic corrosion measurements, in which the Fig. 15. Ground
Model 283 is a ZRA and the Ground connector is connected to one of the Connector.
two metal working electrodes. The Sense Cable connects to the other
working electrode and the Working Electrode plugs into the second pin-jack on the Sense Cable
pod. The Reference Cable connects to the Reference Electrode in the usual manner.
4.8. Cell Safety Switch
This switch provides a direct interrupt of the counter electrode lead. It
should be in the OFF position whenever the cell cables are being handled
or when there is any chance of contact with the cell connections.
Fig. 16. Cell Safety
Switch.
4.9. Dummy Cell Connectors
The internal dummy cells, networks constructed of precision components,
are brought out at these pinjacks (Fig. 17). During calibration, the cell
cables are connected to these pin jacks, allowing the internal dummy cells
to be substituted for an external cell. Schematically, the dummy cells are
as shown in Fig. 18. Fig. 19 shows how the connections to a dummy cell
are made. Appendix D shows plots performed on the ac dummy cell using
the 398 Impedance Software.
Fig. 17. Dummy
Cell Connectors.
Chapter 4 — FRONT PANEL
27
Fig. 18. Dummy Cell Networks.
Fig. 19. Dummy Cell Connections.
4.10. Power Switch
The Power switch and its associated indicator are located at the lower lefthand corner of the front panel. As indicated, when the pushbutton is "in"
(latched), the instrument is powered. In the "out" position, both sides of the
ac line to the instrument are interrupted. The indicator glows whenever the
instrument is powered.
Fig. 20. Power
Switch.
28
Model 283 User’s Manual
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Fig. 21. Model 283 Back Panel.
5.1. Introduction
As shown in Fig. 21, there are three BNC connectors, a preamplifier power connector, two
communications ports, auxiliary interface connector, and an expansion interface connector on
the back panel. The power input assembly is also located there. These items are discussed in
the following paragraphs.
5.2. Power Input
The Power Input assembly is located at the panel's lower right. The operating and safety
considerations germane to this assembly are discussed in Section 2-3, LINE VOLTAGE, and are
not repeated here.
5.3. Accessory Power
Provides ±28 V regulated and ±15 V regulated power for accessory equipment. Up to about 50
mA may be safely drawn from each of these sources. The voltage-pin assignments are depicted
on the back panel directly above the connector as shown in Fig. 21.
5.4. Auxiliary Interface
When the Model 283 is controlled from an external computer, this connector, via the Model 507
Interface, can provide control signals for a Model 303A Static Mercury Drop Electrode.
29
It can send Purge, Stir, and Dispense signals to the Model 303A. But note that the Model 303A is
not cabled directly to this connector. It is cabled to the Model 507 Interface unit, which in turn is
cabled to the Model 283 AUXILIARY INTERFACE connector.
Motor ON/OFF control of a Model 616 or 636 Rotating Electrode System is also possible using
the STIR signal (pin 9).
5.5. RS-232 Connector
This is a serial port for control of the Model 283 from an external computer via an RS-232
interface cable. The communications parameters are set from the front panel of the Model 283.
Note: The maximum potential that can be applied to this port is ±15 V. The Model 283 Command
Set Handbook describes communications protocols and settings. See Appendix C for a pinout
listing.
5.6. IEEE-488 Connector
This is a parallel port for controlling the Model 283 from an external computer via an IEEE-488
(GPIB) interface cable. The GPIB address, terminator characters, and status of the Test Echo
function are set from the front panel of the Model 283. The Model 283 Command Set Handbook
describes communications protocols and settings. See Appendix C for a pinout listing.
5.7. PA Monitor
A 10: 1 attenuated analog of the counter-electrode potential is provided at this connector. The
output impedance is 10 k.
5.8. A & B Connectors
These are BNC connectors provided for future development.
5.9. Expansion Interface
This connector is provided for future development.
30
Model 283 User’s Manual
*HWWLQJ6WDUWHG
6.1. Introduction
Although the Model 283 is a complex and sophisticated instrument, it is easy to use. It can be
controlled either directly from its front panel or from a personal computer.
This chapter describes the functions of the controls, LCD display, and indicator lights on the front
panel. It then shows you how to set up the basic experiment parameters that are common to both
potentiostatic and galvanostatic operation from the front panel. These parameters seldom
require changing. It also shows how to set the RS-232 or GPIB (IEEE-488) communications
parameters necessary for controlling the instrument from a host computer.
After you have set these parameters, you must also set the parameters that are specific to the
kind of experiment you wish to do. To complete your preparation and run your experiment,
continue to either
Chapter 7 to set potentiostatic parameters and run a potentiostatic experiment, or
Chapter 8 to set galvanostatic parameters and run a galvanostatic experiment.
A battery-powered parameter backup system retains all selections and parameter values when
the power is cycled. When the Model 283 is powered up, all selections and parameter values are
restored to the values they had at the end of the previous operating session, except for Cell On,
which, as one would expect, changes to Cell Off. If you wish to restore all of the default values,
hold in any of the keys on the front panel as you power up.
Note: Many of the parameters set from a remote computer via the GPIB or RS-232 bus are
stored in memory locations shared with similar parameters set from the front panel. In some
circumstances this can cause unpredictable interactions between remote parameters and
front-panel parameters. We recommend that you do not mix front-panel and remote control
operations.
Certain conditions that interfere with normal operation will cause error messages to be displayed
on the LCD panel. These messages are explained in Section 6.1 1.
6.2. Polarity Convention
The Model 283 follows the American polarity convention and the display indications are
consistent with that convention. Positive current is cathodic, that is, a current is defined as
positive if reduction is taking place at the working electrode. Negative current is anodic, that is, a
current is defined as negative if oxidation is taking place at the working electrode.
In potentiostatic operation, making the applied potential more positive will cause the current to
become more anodic. Conversely, making the applied potential more negative will cause the
current to become more cathodic. This is true for all potential sources at the external input (EXT
INPUT) connector.
In galvanostatic operation, making the applied potential more positive by any means except
applying a potential to EXT INPUT will tend to make the current more cathodic. Making the
31
applied potential more negative will tend to make the current more anodic. This sense is
reversed at the EXT INPUT connector. There, making the input more positive will make the cell
current more anodic. Making the input more negative will make the cell current more cathodic.
Bear in mind that EXT INPUT is a high-impedance (1 M) input in both potentiostatic and
galvanostatic operation. (in galvanostatic operation, 1 V applied results in a full-scale current,
assuming EXT INPUT is set to ON and OSC IN is set to OFF.)
6.3. Operating Modes
6.3.1. Introduction
This instrument can operate in either of two basic operating modes, Potentiostat or Galvanostat.
The mode in which it is operating at any time is indicated by an illuminated lamp.
In each of these basic operating modes, the cell potential or current can be held constant to
extremely close tolerances, or it can be varied in closely controlled increments. These operating
modes are explained below. To switch between modes, simply press the MODE key on the front
panel.
6.3.2. Potentiostatic
In this mode, the Model 283 controls the potential at the working electrode with respect to the
reference electrode. The potential at the counter electrode is driven to the potential required
(consistent with the ±80 V compliance of the control amplifier) to establish the desired working
electrode potential. The range over which the working electrode potential can be controlled is
±10 V, with ±8 V being available in a single experiment.
6.3.3. Galvanostatic
In this mode, the Model 283 controls the current between the counter and working electrodes at
the specified fraction of the selected current range (up to the maximum of two times the current
range). The counter electrode is driven to the potential required (consistent with the ±80 V
compliance of the control amplifier) to establish the desired cell current. The reference electrode
is not used in the control loop, but can be used to monitor the potential at some point in the
electrochemical cell.
6.3.4. Scanning and Stepping Transitions
Under front-panel control, the Model 283 can hold
the cell potential or current fixed at a single level
during the experiment, or it can vary the potential or
current between three separate programmable
levels. In potentiostatic operation, the separate
levels are called E Initial, E Mid, and E Final. In
Galvanostatic operation, the levels are called I Initial,
I Mid, and I Final.
The transition between the three levels can be in the
form of either a gradual ramp or "scan" between
levels, or a sudden sharp "step." So there are
actually a total of six modes of operation available:
32
Potentiostatic, where cell potential is held
constant.
Fig. 22. Transitions.
Model 283 User’s Manual
Potentiostatic Scan, with a gradual ramp between the three levels of cell potential. You can
program the rate of change ("SCANRATE") of the potential between levels.
Potentiostatic Step, with sharp steps between the three levels of cell potential.
Galvanostatic, where cell current is held constant.
Galvanostatic Scan, with a gradual ramp between the three levels of cell current. You can
program the rate of change (“SCANRATE”) of the current between levels.
Galvanostatic Step, with sharp steps between the three levels of cell current.
The lengths of time for which each of the three levels of potential or current are held constant
during the experiment are called T Init, T Mid, and T Final. Each time can be separately
programmed (or omitted entirely) . See Delays in Appendix B, the Technical Reference, for a
detailed discussion of these parameters.
Note that the Model 283 does not apply a linear scan, but rather a "staircase" scan. However, as
long as the individual steps are very small relative to the range scanned, linear scan theory will
apply to a close approximation. The nominal step size is the sr-an rate/250, or 250 µV,
whichever is larger, Under remote control via the rear panel GPIB or RS-232 port, steps as small
as 25 µV (MR = 1), or 2.5 µV (MR = 0), can be attained as explained in the Model 283 Command
Set Handbook).
Example: With a scan rate of 1 V/s, the step size will be 4 mV (1000/250 = 4).
6.4. Controls and Indicators
In local control (when you are not controlling the Model 283 from a separate computer), you
communicate with the Model 283 using its front-panel controls and liquid crystal display (LCD).
The controls – a large knob and an array of push-button keys – are used to set the test
parameters and select the operations to be performed. The LCD panel provides continuous, realtime information on the experiment, including the parameters initially set and the cell potentials
and currents measured or applied as the experiment progresses. Chapter 4, FRONT PANEL,
describes the front-panel controls in detail and that information will not be repeated here. This
section focuses on the LCD and menu operations.
6.5. Using the LCD Menu Screens
6.5.1. Introduction
In local control, the LCD panel and its associated controls provide the means for communication
between the researcher and the Model 283. The researcher first sets the required experiment
parameters on the appropriate menu screens, using the VALUE knob, and then presses F3 to
start the experiment. At any time during the scan the user can reverse the scan direction,
suspend its progress and then restart it, or stop it entirely.
The LCD panel can display four lines of alphanumeric characters. The information shown on
these lines depends on which menu screen is displayed. Under local control, eight screens are
available: the [System interface] and [System Default] screens, three potentiostat screens, and
three galvanostat screens. The MODE and SYSTEM keys above the display allow you to cycle
through the screens.
When the Model 283 is under control of an external computer, the LCD panel changes to the
REMOTE screen. All the front-panel controls except the Cell On key, Cell Safety switch, the
Power switch and the F5 function key are disabled, but the indicator lamps continue to function.
Chapter 6 — GETTING STARTED
33
Pressing F5 (now called the LOCAL key) will return you to local control and bring up either the
[Potentiostat] or [Galvanostat) menu screen. You ran use the MODE key from either of these
screens to move to any other local-control menu screen.
Note: We recommend that you do not mix front-panel and remote operations. Please see the
note in Section 6. 1.
6.5.2. Common Screen Elements
The top line of the LCD panel (Fig.23 )
shows the name of the current menu screen
in brackets ("REMOTE" is displayed when
the instrument is under control of an
external computer). On the [System
Fig. 23. Typical LCD Menu Screen.
Interface] menu, the top line also shows the
name of the instrument and the version of the firmware installed.
The second line of the display continuously shows, on the left side of the line, the measured and
corrected cell potential as the experiment progresses. If a cell potential overload condition
occurs (see OVERLOAD Indicators in Section 4.2F), "E = OVERLOAD" will be displayed.
The center of this line continuously shows the actual cell current (1) without I Offset applied.
Note: If a current overload condition occurs, "I = OVERLOAD" will be displayed here. This
means that the current is too large to be measured. It does not mean that the cell control loop is
out of control.
The right side of this line displays either the current with offset applied (i) or the total charge (Q)
that has passed through the cell since the beginning of the experiment. To display the value of i
or Q, press F1 (see "Bottom Row Functions" below).
6.5.3. Setting Parameters
In local control, the third line of the display shows one of several experiment or communications
parameters that can be set by the operator. To change the value of the displayed parameter,
simply turn the VALUE knob. The PREV and NEXT PARAMETER keys, located under the
VALUE knob, allow you to display in turn each of the adjustable parameters. The value of any
parameter displayed on the third line can be reset with the VALUE knob.
A useful feature of the Model 283 is that you can change many of the parameters at any time
during a scan, as well as before the scan begins. You can change the following parameters while
the scan is in progress:
E INIT
I lNIT
T INIT
SCANRATE
E MID
I MID
T MID
CYCLES
E FINAL
I FINAL
T FINAL
[email protected]
When the Model 283 is under control of an external computer, the third line of the REMOTE
screen may be blank, it may display up to 40 characters of text typed on the computer following
the TYPE command, or it may display a communications error message (see Section 6.11).
6.5.4. Bottom Row Functions
The fourth (bottom) line of the display shows the function currently assigned to each of the "soft”
function keys (F1 through F5). You will note that the functions of some keys vary according to
the menu screen displayed. In some menus, not all of the function keys are used.
34
Model 283 User’s Manual
6.6. Setting Communications Parameters
6.6.1. Introduction
The Model 283 can be controlled remotely from a personal computer running standard PARI
electrochemistry software. Instructions for remote operation using the PARI Electrochemical
Command Set built into the Model 283 are given in the separately bound Model 283 Command
Set Handbook.
Either the RS-232 serial port or the IEEE-488 (GPIB) port on the rear panel of the Model 283 can
be used for communications with the host computer. If the IEEE-488 interface is used, the host
computer must be equipped with a GPIB interface card. For details of hardware requirements,
refer to the manual for the software to be run on the host computer. PARI software is designed to
interface an IBM or IBM-compatible computer equipped with a National Instruments PC2, PC-2A,
PC-AT, or MC-GPIB GPIB card.
Before the Model 283 and a host computer can successfully talk to each other, certain
communications parameters have to be set in both. For GPIB communications, the instrument
must be set to the address assigned to 4 at ft computer, and the terminator character required by
the host must be set. For RS-232 communications, the baud rate, parity, number of data and
stop bits, and terminator character must match the host settings.
Note that with most software running on an IBM-compatible computer, the terminator must be a
CR and both serial and GPIB echo must be off. Further details of communications protocols for
GPIB and RS-232 interfacing are given in the Model 283 Command Set Handbook.
6.6.2. [System Interface] Menu Screen
The [System Interface] menu screen is used to set up certain basic operating parameters for
your system. All but one of these parameters (KNOB TIMEOUT) concern communications
between the instrument and a host computer, and do not have to be set if you are operating from
the front panel of the Model 283.
To set the communications parameters on the Model 283, move to the [System Interface] menu
on the LCD panel by pressing the SYSTEM key. Then, press the PREV or NEXT PARAMETER
key until a parameter to be set appears on the third line of the display. Turn the VALUE knob to
set the parameter. Press the PREV or NEXT PARAMETER key again to display the next
communications parameter, and set ft in the same fashion. Continue this process until all
required parameters have been set.
The SYSTEM key allows you to access the [System Interface] menu screen from any
potentiostatic or galvanostatic menu. It also moves you from the [System Interface] menu to the
[System Default] menu and from the [System Default] menu to a potentiostatic or galvanostatic
menu (see Fig. 11).
The MODE key is used to move directly from the [System Interface] menu screen to one of the
potentiostatic or galvanostatic menus, as shown in Fig. 10. (it is also used to move between the
potentiostatic and galvanostatic experiment modes).
6.6.3. [System Interface] Menu Line 3 Parameters
The operating parameters that can be displayed on line 3 of the [System Interface] menu (and
adjusted with the VALUE knob) are listed below. Details of these parameters are given in
Appendix B of this manual and in the appendices of the Model 283 Command Set Handbook.
Chapter 6 — GETTING STARTED
35
Note that when you are controlling the Model 283 from a host computer via the RS-232 bus, the
Baud rate, number of data bits, parity, and number of stop bits must be the same for both the
Model 283 and the serial port on the host computer.
GPIB ADDR (1 to 30): The normal GPIB address setting for use with PARI software is 14. If you
are using other software, see the software manual for its requirements.
TERMINATOR (CR or CRLF): The terminator required for GPIB communications with IBM PCcompatible computers running PARI software is CR.
GPIB ECHO (OFF or ON): During normal operation, GPIB ECHO should be set to OFF. When it
is ON, every character transmitted or received via the GPIB port will be echoed to the RS-232
Interface Connector. This feature is particularly useful when developing programs. If a "dumb"
CRT terminal is connected to the RS-232 Interface, the programmer will see all communications
on the CRT.
SERIAL BAUD (110/300/600/1200/2400/4800/ 9600/19200): This sets the Baud rate for RS-232
communications. Hardware handshaking is recommended for the higher settings.
SERIAL PRTY (NONE, EVEN, ODD): This determines parity checking for RS-232
communications. Parity maintenance provides a direct way of detecting garbled data if the
computer is programmed to only accept words having the selected parity. If a word having
incorrect parity is read, it is a message to the computer that data loss is occurring.
SERIAL BITS (7 or 8): This sets the number of bits in the data word in RS- 232
communications. Eight bits are required for binary data loads and dumps.
SERIAL STOP (1 or 2): This sets the number of stop bits in RS-232 communications. Two stop
bits give more reliable communications at high baud rates, but slows the data transfer.
SERIAL ECHO (OFF or ON): Normally OFF. If ON is selected, each character received via the
RS-232 port will be echoed back to the character source. The RS-232 echo is normally used only
when the Model 283 is connected to a CRT terminal.
Note: Do not confuse this function with the GPIB ECHO.
KNOB TIMEOUT (DISABLED, 1 to 120 s): To prevent someone from inadvertently changing an
experiment parameter by brushing against the VALUE knob, you can disable the knob after using
it. You can specify the period of time it wafts after its last use before becoming inactive (the
“timeout” period). At the end of the timeout period the knob will have no effect on parameter
settings, and the LCD panel will display "KNOB TIMEOUT HIT ANY KEY." Press any key to
reactivate the knob. When DISABLED is selected, the knob remains active and will not time out.
6.7. Common Experiment Parameters
6.7.1. [System Default] Menu Screen
The [System Default] menu screen allows you to view and, if necessary, adjust parameters that
normally do not require resetting between experiments. As in the other menus, these parameters
can be displayed sequentially on the menu (line 3) by pressing the PREV and NEXT
PARAMETER keys. After you select a parameter, you may change its setting with the VALUE
knob.
36
Model 283 User’s Manual
The SYSTEM key allows you to access the [System Default] menu screen from the [System
Interface] menu. It also moves you from a system menu to a potentiostatic or galvanostatic
menu (see Fig. 11). The MODE key also can be used to move from the [System Default] menu
screen to one of the potentiostatic or galvanostatic menus.
6.7.2. [System Default] Menu Line 3 Parameters
The experiment parameters that can be displayed on line 3 of the [System Default) menu (and
adjusted with the VALUE knob) are listed below. Details of these parameters are given in
Appendix B.
CELL TYPE: Always indicates REAL
Note: In the case of the Model 263A Potenitiosat/Galvanostat, the alternate selection
DUMMY is also provided, which allows the internal dummy cell network to be selected
automatically. In the case of the Model 283, there are two internal dummy cells. Either
ran be accessed via front-panel connectors by using the cell cables as described in
Chapter 4. The dummy cell load is useful for determining that the Model 283 is
functioning correctly.
EXT INPUT (OFF or ON): determines whether the front-panel EXT INPUT connector will
accept an applied signal without applying a scaling factor to it. Use ON if the applied signal
has a suitable amplitude and you do not wish to scale it. OFF is used either when no signal is
to be applied, or when an applied signal is too large or too small and you wish to scale it with
the OSC GAIN parameter.
Note that both EXT INPUT and OSC IN (see below) cannot be set to ON at the same time. If
you are unsuccessful in turning one on, check that the other is off.
OSO IN (OFF or ON): determines whether the front-panel EXT INPUT connector will accept
and scale an applied signal. Use ON if the applied signal is too large or too small and you
wish to scale it by a factor of 0.02. 0.2, or 2.0. OFF is used either when no signal is to be
applied, or when an applied signal is of a useful amplitude with unity gain (in that case, use
EXT INPUT = ON).
Note that both EXT INPUT and OSC IN cannot be set to ON at the same time. If you are
unsuccessful in turning one on, check that the other is off.
If you set OSC IN = ON, press the NEXT, PARAMETER key once and set OSC GAIN (see
below).
OSC GAIN (X.O2, X.2, or X2): sets the OSC GAIN factor to one of the three available
values: 0.02, 0.2, or 2.
LINE SYNC (OFF or ON): determines whether data acquisition will be synchronized with the
power-line frequency. When ON is selected, the sample is taken when the next linefrequency zero crossing occurs. This occurs every 16.6 ms (60 Hz power) or every 20 ms
(50 Hz power). If LINE SYNC = OFF, samples are taken at the rate determined by the
internal time base of 4 ms. The default state is OFF.
I/E FILTER (OFF or ON): The Model 283 has three fillers - an I-Channel low-pass filter, an
E-Channel low-pass filter and an I/E Converter low-pass filter that reduces the bandwidth of
the I/E converter. The I and E Channel low-pass filters do not affect the output at the I
Monitor or E Monitor outputs, but rather affect the E and I signals made available for
Chapter 6 — GETTING STARTED
37
monitoring at the display and for digital storage and processing. The I/E Filter on the other
hand does affect the signal at the I Monitor connector.
When the I/E Filter is set to OFF, none of these filters are selected. When the I/E Filter is set
to ON, two filters are selected. The first is the I/E Filter; the second is the I-Channel low-pass
filter.
Note: The E-Channel low-pass filter can not be selected from the front panel. It can,
however, be selected via one of the rear-panel interface ports under computer control.
See the discussion of the FLT command in the Command Set Handbook for detailed
information.
The effect of the I/E Filter depends on the current range selected. Cut-off frequencies for this
filter at each current range are given in Appendix B under Filters. This filter is often helpful
when making low-current measurements on large electrodes because it reduces the noise at
the I MONITOR output. The disadvantage of using the filter is that the I MONITOR output
response time is degraded.
It may be advantageous to synchronize data acquisition with the power line frequency when
filtering. This can be done by setting LINE SYNC = ON (see LINE SYNC above).
The I/E filters can cause unpredictable effects on your experiment if AUTO current ranging is
in use. If I/E FILTER = ON is selected, we recommend manual current ranging.
BANDWIDTH (HI STABILITY or HI SPEED): sets the bandwidth/stability parameter. For the
fastest response, choose HI SPEED. For stability, choose HI STABILITY.
I AUTO LIMIT: sets the most sensitive current range to which the Model 283 can
automatically range.
UPDATE Q W/CELL OFF (NO or YES): The final current integral (Q), in coulombs, can be
displayed, with continuous updating as the measurement progresses. The final current
integral is the net charge (including I Offset) that has passed through the cell since the
beginning of the experiment while the cell was on.
In a perfect instrument and cell system, Q of course could not change when the cell is
disconnected, because no cell current would flow. But in a real system, no matter how
precise, some small charge may appear as a result of drift and other circuit variations. Thus,
setting UPDATE Q W/CELL OFF = NO prevents charge from accumulating when the cell is
off. Choosing YES allows it to accumulate, and might help to estimate drift errors.
6.8. Resetting Parameters to Default Values
6.8.1. Introduction
In certain circumstances it may be desirable to return to the default parameter values, which are
stored in battery-backed RAM. There are two ways you can return to the default values of the
parameters. One method resets only the experiment parameters - those that appear on the
[System Default] menu and on the potentiostatic and galvanostatic menus. It does not alter the
parameters on the [System Interface] menu (communications parameters and KNOB TIMEOUT.
The second method resets both groups of parameters, including those on the [System Interface]
menu. Both procedures are described in the following.
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Model 283 User’s Manual
6.8.2. To reset only the experiment parameters
With the instrument running, press the SYSTEM key to display the [System Interface] menu
screen. Then, press "Reset" (F2). The following query will be displayed on the LCD panel:
RESET SYSTEM?..
If you press YES (F4), all experiment parameter selections will be cleared and default values will
be restored. If you press NO (F5), the parameters will not be reset and the SYSTEM menu
screen will reappear.
6.8.3. To reset both groups of parameters
With the instrument off, hold down any front-panel key and press the POWER switch. The
following message will be displayed on the LCD panel:
KEY HELD DURING POWER UP
SYSTEM RESET PERFORMED
(third line is blank)
(fourth line is blank)
When the message clears, the following parameters are reset to their default values.
Command Delimiter = 44 (ASCII comma)
GPIB Address = 14
Baud Rate = 9600
Parity = None
Data Bits = 8
Stop Bits = 1
RS232 Echo = OFF
Knob Timeout = disabled Cell = OFF
Terminator = CR
GPIB Echo = OFF
Front Panel Time Base = 4 ms
Note that the foregoing two reset procedures do not clear the calibration values or recalibrate the
instrument. If the battery has been replaced, you will also have to recalibrate. Refer to Section
6.9 below for the calibration procedure.
6.9. Calibrating the Model 283
In the [System Interface] menu, F1 is assigned the Calib (Calibrate) function. This function is
used to recalibrate the Model 283. Calibration values are stored in battery-backed RAM. If the
battery has been replaced, use this procedure to recalibrate the instrument. Before recalibrating,
allow the instrument to warm up for at least ½ hour. Note that the calibration is done substituting
precision resistors for the cell. Both dc and ac precision dummy-cell networks, accessible from
the front panel, are built into the Model 283. Section 4.9 describes these networks and the
connections required to access them for calibration purposes.
To recalibrate the instrument, press the SYSTEM key to display the [System Interface] menu
screen, and then press CALIB (F1). The following query will be displayed on line 3 of the LCD
panel:
CALIBRATE SYSTEM?...
Chapter 6 — GETTING STARTED
39
If you press NO (F5), recalibration will not proceed and the [System Interface] menu screen will
reappear. If you press YES (F4), the CALIBRATING screen is displayed. As each step in the
calibration procedure is performed in sequence, its number and name appear on the second line
of the screen. The third line will contain further information during some calibration steps; during
others it will be blank. The fourth line shows the constantly changing calibration parameter
values.
If calibration fails, for any reason, the second line display (step number and name) will freeze,
the third line will now say FAIL, and the fourth line will say HIT ANY KEY TO CONTINUE.
Pressing any key will leave the CALIBRATING screen and return to the [System Interface] menu.
You may now run experiments, but the results will be suspect because you won't know how far
the instrument is out of calibration.
If calibration fails, first check the cable connections to the dummy cell. If they appear to be in
order, we recommend that you not take the advice on the fourth line and "hit any key." Instead,
leave it in the CALIBRATING screen and call the PARI Service Department to report the number
and name of the step that failed. This information will continue to be shown on the second line of
the display. The service technician will diagnose the problem and advise you as to what action to
take.
6.10. Determining Installed Options
In the [System Interface] menu, F3 is assigned the Options function. The Model 283 is designed
for easy expansion to accommodate future enhancements now under development or
envisioned. As these optional features become available, the Options function will allow a user
or service technician to determine easily exactly how the system is configured.
To see which options are installed, press the SYSTEM key to display the [System Interface]
menu screen, and then press "Options" (F3). A string of numbers separated by spaces will be
displayed on the third line of the LCD panel. Each number is in the range 90 to 99 and indicates
the presence of an installed option. The number 90 indicates the presence of the basic system
PC boards and should always be displayed.
On line 4 of the LCD panel, the prompt
HIT ANY KEY TO CONTINUE
will be displayed. After you have read the display of options, press any key to return to the
[System Interface] menu.
6.11. Error Messages
Certain conditions that interfere with normal operation will cause error messages to be displayed
on the LCD panel. The message will give a warning statement about the type of error,
information about the cause (sometimes in a numeric code), and usually advice about what
action to take.
Note that errors indicated on the LCD panel are not related to the software error codes that you
can display on the monitor of a host computer with the ERR command.
The following shows the error message screens that may appear on the LCD panel when a
problem occurs.
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Model 283 User’s Manual
CATASTROPHIC FAILURE
MISSING BOARDS (means it can't find a PC board) (error code numbers will appear here)
SYSTEM HALTED
CATASTROPHIC FAILURE
BAD CRC ON BOARDS (means a memory failure) (error code numbers will appear here)
SYSTEM HALTED
If either of the foregoing two error message screens is displayed, call the PARI Service
Department and report the error code displayed on line three. The service technician will
diagnose the problem and advise you as to what action to take.
BAD BOARD ID SHADOW CRC
BATTERY PROBABLY DEAD
CALIBRATION REQUIRED
HIT ANY KEY TO CONTINUE
The Model 283 is equipped with a long-life lithium battery that enables retention of the calibration
settings in memory. The battery has a life of approximately two to five years, depending on how
much you use the instrument. If the foregoing screen is displayed, you will probably have to send
the instrument to an authorized PARI repair facility for battery replacement. You cannot replace
the battery yourself.
You can use the instrument without the battery, but you will have to perform the calibration
procedure every time you power up. If you need to complete some work first before you send the
unit, you ran calibrate it and continue with your work. Before calibrating, allow the instrument to
warm up for at least ½ hour.
To recalibrate, first press any key to clear the error message. Then, press the SYSTEM key to
bring up the [System Interface] menu screen. Follow the calibration instructions in Section 6.9.
If the error message reappears, call the PARI Service Department and report it. The service
technician will diagnose the problem and advise you as to what action to take.
BOARD(S) CHANGED: (new bd has different rev. level)
SYSTEM: (number) OPTIONS: (number)
MAY REQUIRE CALIBRATION
HIT ANY KEY TO CONTINUE
If the foregoing error message screen is displayed, you should recalibrate the instrument. Before
recalibrating, allow the instrument to warm up for at least ½ hour.
To recalibrate, first press any key to clear the error message. Then, press the SYSTEM key to
bring up the [System Interface) menu screen. Follow the calibration instructions in Section 6.9.
(means PC communications have failed)
Chapter 6 — GETTING STARTED
41
In the foregoing error message screen, the words "COMM ERROR” on the fourth line are
followed by a two-digit hexadecimal error code.
If this screen is displayed either (a) when you turn on the Model 283 or (b) while you are
controlling the Model 283 from a host computer, call the PARI Service Department and report
the error code. The service technician will diagnose the problem and advise you as to what
action to take. Then, press LOC (F5) to clear the error message.
If the foregoing COMM ERROR message screen is displayed while you are trying to establish
communications between a host computer and the Model 283 via the RS-232 bus, first press
LOC (F5) to clear the error message. Then, check that the following communications parameters
are set correctly on the Model 283 to match the settings on the computer:
Baud rate
Number of data bits *
Number of stop bits *
Parity
Terminator (usually should be CR)
After you have reset any communications parameters that don't match the computer software
requirements, send an Action command from the computer to the Model 233. If the command is
executed, the problem has cleared. If the error message returns, call the PARI Service
Department and report the error code.
The following is not an error message but a cautionary message to warn you that experiment and
communications parameters have been reset to their default values:
KEY HELD DURING POWER UP
SYSTEM RESET PERFORMED
(third line is blank)
(fourth line is blank)
6.12. Connecting a Pen Recorder or Oscilloscope
The potential of the working electrode with respect to the reference electrode is continuously
provided at the E MONITOR connector. This signal can be used to drive the X-axis drive signal
line of a pen recorder or oscilloscope.
A meaningful E MONITOR signal is provided as long as there is a reference electrode. If the
reference electrode is not connected, as might be the case in galvanostatic operation, the E
MONITOR signal is undefined.
In Potentiostatic operation, if positive feedback or current interrupt iR Compensation is on, the
compensation corrects the E MONITOR signal level for the iR drop.
The E MONITOR signal is analog inverted with respect to the applied potential. For example, if
the applied potential is +1 V, the potential at the E MONITOR connector will be -1 V.
The output impedance at the E MONITOR and I MONITOR connectors is 50 . We suggest
using either a PAR RE0150 X-Y recorder or an RE0151 X-Y-T recorder, as both instruments are
designed for use with the Model 283. Simply connect the X-axis drive signal line of the recorder
to the E MONITOR connector, and the Y-axis drive signal line to the I MONITOR connector.
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Model 283 User’s Manual
6.13. Adding an External Signal
The EXT IN connector on the front panel provides a means for summing external control
potentials with those generated in the instrument or transmitted to it from an external computer.
This gives you a way to add any customized waveform function you wish. The control signals
could be generated by, for example, a PARI Model 175 Universal Programmer to provide rapid
scanning and true analog cyclic voltammetry. Other waveform generators, a lock-in amplifier, or
a frequency response analyzer could be used. The applied signal can be scaled up or down, if
desired, by a factor of 2, 0.2, or 0.02.
To control the EXT IN connector from the front panel, press the SYSTEM key until the [System
Default] menu appears on the LCD panel. If the applied signal has a suitable amplitude and you
do not wish to scale it, press the PREV or NEXT PARAMETER key until "EXT INPUT =" appears
on the third line of the menu. Then, turn the VALUE knob until "EXT INPUT = ON" is displayed.
To disconnect, turn the knob until "EXT INPUT = OFF."
If the applied signal is too large or too small and you wish to scale it, press the NEXT
PARAMETER key until "OSC IN =" is displayed on the third line of the menu. Turn the VALUE
knob to "OSC IN = ON." Then, press the NEXT PARAMETER key again until "OSC GAIN ="
appears on the third line of the [System Default] menu. Turn the VALUE knob to set the OSC
GAIN factor to one of the three available values: 0.02, 0.2, or 2. To disconnect, set "OSC IN =
OFF."
Note that both EXT IN and OSC IN cannot be set to ON at the same time. If you are
unsuccessful in turning one on, check that the other is off.
When the connector is ON (connected), the EXT IN indicator lights and the instrument becomes
responsive to potentials applied to the connector. When it is OFF (disconnected), the indicator
goes out, indicating that potentials applied to this input will be ignored.
6.14. Connecting a Model 303A SMDE
When the Model 283 is controlled from an external computer, a can send PURGE, STIR, and
DISPENSE signals to a PARI Model 303A Static Mercury Drop Electrode. Instructions for
sending these commands are given in the Model 283 Command Set Handbook.
Also required is a PARI Model 507 Interface, which must be purchased separately. To control the
Model 303A, connect it to the Model 507 Interface and the Interface unit to the AUXILIARY
INTERFACE connector on the back of the Model 283. The required Gables are provided With
the Model 507 Interface. Refer to the Model 507 Interface Installation Guide, PARI Part Number
222556, it you need more detailed installation instructions.
6.15. Connecting a Model 616 or 636 Rotating Electrode
In both the 616 and the 636 there is provision for stopping the motor with a TTL level signal
applied to a Motor Stop (616) or Motor Control (636) jack. In both instruments an internal jumper
determines whether the motor-stop function is enabled by a TTL 1 or TTL 0. The TTL 1 STIR
signal provided on pin 9 of the 283's rear panel AUXILIARY INTERFACE connector can be used
as a motor on/off control signal to the 616 or 636. The level on pin 9 of the AUXILIARY
INTERFACE connector in turn is controlled from an external computer via the STIR command.
Chapter 6 — GETTING STARTED
43
The front-panel D/A OUTPUT level, controlled by the SETOUT command, is suitable for
controlling the speed of a 616 or 636. Alternatively, the dc level at the OUTPUT connector,
controlled by the SETOUT2 command, could be used. In both the 616 and the 636 the dc level
applied to the INPUT jack sets the motor speed. A BNC to double-banana adaptor cable should
be used.
6.16. Supplying Accessory Power
The ACCESSORY POWER connector on the rear panel can provide ±28 V regulated and ±15 V
regulated power for accessory equipment. Up to about 50 mA may be safety drawn from each of
these sources. The voltage available at each connector pin is defined in Appendix C.
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Model 283 User’s Manual
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7.1. Introduction
This chapter shows you how to set the experiment parameters for a potentiostatic experiment
and explains how to run your potentiostatic experiments. In the course of following these
discussions, you will come across many technical terms specific the Model 283 as well as to
potentiostats and galvanostats in general. Should you encounter an unfamiliar term, or find that
the discussion provided in this chapter isn't sufficiently detailed, please see the Technical
Reference in Appendix B. In the interest of streamlining the procedures chapters, detailed
discussions of the parameters and other technical terms have been placed in a separate
appendix (Appendix B), which is alphabetically arranged and quite thorough.
7.2. Potentiostatic Modes
Under front-panel control, the Model 283 can hold the working electrode potential fixed at a
single level during the experiment, or it can vary the potential between three separate
programmable levels, called E lnit, E Mid, and E Final.
The transition between the three levels can be in the form of either a gradual ramp or "scan"
between levels, or a sudden sharp "step." So there are actually three modes of potentiostatic
operation available:
Potentiostatic with a fixed potential [Potentiostat], where the potential at the working
electrode is held constant.
Potentiostatic Scan [potentiostatic Scan], with a gradual ramp between the three levels of
working electrode potential. You can program the rate of change ("SCANRATE") of the
potential between levels.
Potentiostatic Step [Potentiostatic Step], with sharp steps between the three levels of
working electrode potential.
The lengths of time for which each of the three levels of potential are held constant during the
experiment are called T lnit, T Mid, and T Final. Each time can be separately programmed (or
omitted entirely).
To run a potentiostatic experiment from the front panel, first set up the basic parameters as
described in Chapter 6. Then, press the MODE key as many times as necessary to display the
menu screen for the potentiostatic mode you wish to use: [Potentiostat], [Potentiostatic Scan], or
[Potentiostatic Step].
After you select the appropriate menu screen, use the PREV and NEXT PARAMETER keys to
display each experiment parameter in turn. The parameters used in each potentiostatic mode are
described in the following sections. More detailed explanations are given in Appendix B. If the
default value of any parameter is not satisfactory for your experiment, use the VALUE knob to
change it.
45
7.3. Setting Fixed-Potential Experiment Parameters
The [Potentiostat] menu allows you to set the following experiment parameters used in steadystate potentiostatic operation, where the potential at the working electrode is held constant with
respect to the reference electrode.
POTENTIAL at the working electrode.
IR MODE (OFF or ON and, if ON, whether Positive Feedback (PFIR) or Current Interrupt
(IRUPI) iR compensation is to be used).
PFIR COMP. When Positive Feedback iR compensation is selected, you specify the
amount of resistance here (in ohms).
IRUPT T1 sets the increment of time between the interruption of current to the cell at the
start of a periodic Current Interrupt iR Compensation cycle and the first voltage sampling.
This voltage sampling, in conjunction with the second sampling at IRUPT T2, is used to
extrapolate back to the interrupt potential in determining the Current Interrupt iR
Compensation correction factor. The range is 10 µs to 2000 - (IRUPT T2) µs. The default
value is 10 µs on the 100 mA range and 75 µs on all other ranges. Note that IRUPT T1 +
IRUPT T2 may not exceed 2000 µs. Note that IRUPT T1 and IRUPT T2 are independently
set for all ranges, and must be separately set for each one,
IRUPT T2 sets the increment of time between the first voltage sampling during a periodic
Current Interrupt iR Compensation cycle and the second voltage sampling. The voltage
samplings are used to extrapolate back to the interrupt potential in determining the Current
Interrupt iR Compensation correction factor. The range is 10 µs to 2000 - (IRUPT T1) µs.
The default value is 10 µs on the 100 mA range and 75 µs on all other ranges. Note that
IRUPT T1 + IRUPT T2 may not exceed 2000 µs. Note that IRUPT T1 and IRUPT T2 are
independently set for all ranges, and must be separately set for each one.
IRUPT (Intermittent Current Interrupt) sets the number of points between current interrupts in
Current Interrupt iR Compensation. The range is 1 to 32,767 points, with a default of 5
points. As the time base used in local operation is 4 ms, 5 points is equal to 20 ms.
IRPC (Current Interrupt Percent Correction) is the percent of correction applied in Current
Interrupt iR Compensation. The range is 0% to 200%. The default value is 100%.
I OFFSET (current offset) allows you to specify a current value to be mathematically
subtracted from the cell current before it is displayed. The result of this subtraction is
displayed as “i” and accumulated over time as “Q”. That is, i = I -(I OFFSET), where I
OFFSET can have a positive or negative value.
Note that there is no actual current subtraction, only a numerical calculation. Thus current
offset does not affect the potential at the I MONITOR connector.
The offset is specified in units of current. The offset range is ±2 times the full-scale current
range in effect at the time I OFFSET is set.
These parameters are explained in greater detail in Appendix B. After you have set them as
required for your experiment, follow the directions in Section 7.6 for running your experiment.
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Model 283 User’s Manual
7.4. Setting Scanned-Potential Experiment Parameters
The [Potentiostatic Scan) menu is used to set the experiment parameters for the Potentiostat
Scan mode. In this mode, the Model 283 varies the potential of the working electrode in a
gradual sweep or ramp between steady-state levels. Many parameters are the same as for fixedpotential experiments and the discussions in Section 7.3 apply fully. However, there are some
that are unique to scanned-potential experiments, as follows.
E INIT, the potential at the working electrode during the first steady-state stage of a scan or
step sequence.
E MID, the potential at the working electrode during the second steady-state stage
(sometimes called the "vertex”) of a scan or step sequence.
E FINAL, the potential at the working electrode during the third steady-state stage of a scan
or step sequence.
T INIT, the length of time that E INIT is maintained at the working electrode.
T MID, the length of time that E MID is maintained at the working electrode.
T FINAL, the length of time that E FINAL is maintained at the working electrode.
SCANRATE, the rate of change of the potential at the working electrode between E INIT and
E MID, and between E MID and E FINAL.
CYCLES allows selection of three different scan or step sequences: HALF CYCLE, FULL
CYCLE, and CONTINUOUS. The cycle setting determines the number of separate steadystate potential levels that will be used at the working electrode during your experiment.
[email protected] determines the working electrode potential at the end of the scan or step
sequence. If you select OFF, the cell will be turned off (counter electrode connection
interrupted) at the end of the programmed cycle. If you select E INIT, the working electrode
potential will be returned (stepped sharply) to E lNIT.
If you select E FINAL, the working electrode potential remains at its last value in the
sequence. In the FULL CYCLE mode, this is E FINAL. But note that in HALF CYCLE
operation, the last potential level reached in the sequence actually is E MID.
Also note that in the CONTINUOUS cycle mode, the experiment doesn’t end until the STOP
key (F3) is pressed. At that point, the working electrode potential returns to E INIT.
These parameters are explained in greater detail in Appendix B. After you have set them as
required, follow the directions in Section 7.6 to run your experiment.
7.5. Setting Stepped-Potential Experiment Parameters
In the Potentiostat Step mode, the Model 283 varies the potential of the working electrode in
sharp steps between steady-state levels. The experiment parameters that can be set from the
[Potentiostatic Step] menu are the same as those set from the [Potentiostatic Scan] menu,
except that there is no SCANRATE setting. After you have set the parameters as required, follow
the directions in Section 7.6 to run your experiment.
Chapter 7 — RUNNING POTENTIOSTATIC EXPERIMENTS
47
7.6. Running Your Experiment
7.6.1. Introduction
After you have connected your equipment and set all required parameters, you are ready to
begin your experiment. After activating the cell connections (Cell Safety switch and Cell On
key), you will start the experiment and control its progress with the soft function keys, F1
through F5, below the LCD panel.
The functions assigned to these keys in each of the potentiostatic modes are displayed on the
bottom line of the menu screen. These functions are described below. If something goes wrong
and an error message is displayed.
7.6.2. F1 (Coulombs or offset I)
This key selects the parameter to be displayed on the right side of the second line of the menu
screen.
By pressing the F1 key, you can display either of two parameters on this line: net current with
I OFFSET applied (i) or the final current integral (Q). The final current integral is the net charge,
after the algebraic addition of I OFFSET, that has passed through the cell since the beginning of
the experiment while the cell was on (or since the coulometer was reset). It is expressed in
coulombs.
7.6.3. F2 (Q-Reset)
The F2 key has the Q Reset (Q-Reset) function. When F2 is pressed, the following query is
displayed on line 3 of the LCD panel:
RESET COULOMBS?.
If you press YES (F4), it resets the coulometer to zero and reestablishes the initial scaling factor,
as set by the selected current range. If F1 has been used to display Q, you will see the final
current integral (in coulombs) on the second line of the display reset to zero and then begin to
increment as charge accumulation resumes.
If you press NO (F5), the coulometer is not reset and the previous menu screen reappears.
7.6.4. F3 (Start or Stop)
The F3 key is used to start a scan. When it is pressed, the scan progresses as programmed.
After the scan begins, the function assigned to F3 changes to 'Stop", which continues to be
displayed even after the scan goes to completion. Pressing F3 during a scan ends the scan
sequence and immediately reestablishes E INIT. Pressing it after the scan ends also restores
E INIT.
7.6.5. F4 (Hold or Resume)
Pressing the F4 key during a scan causes the scan to temporarily haft. When the key is pressed
again (it will now be labeled "Resume"), the scan resumes.
If a "Hold" occurs when a potential is applied, it will continue to be applied (assuming that the
CELL ON key is ON). This is true if the hold takes place at any time during the scan sequence.
The scan simply halts and the potential in effect at the moment of the haft continues to be
applied. Time is not counted for the duration of the hold.
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Model 283 User’s Manual
If F2 (Q-Reset) is pressed to reset the coulomb count, a prompt appears asking whether you
want to proceed. To provide a way to respond to the query, F4 is temporarily reassigned the YES
function.
7.6.6. F5 (Reverse or Bypass)
In the Potentiostat Scan mode, the F5 key is assigned the "Reverse" function. Pressing F5
during a scan reverses the direction of the scan.
In the Potentiostat Step mode, the F5 key has a different function: Bypass. Pressing Bypass
before or during the programmed T INIT, T MID, or T FINAL delay in the scanning sequence
temporarily overrides that delay and sets it to a minimum (actually 4 ms). The scanning
sequence then immediately advances to the next step. For example, if F5 is pressed during the
T INIT interval, the sequence would immediately advance to the first scan. In half-cycle or
single-cycle scanning, if the next step would advance the sequence to the end of the scan, the
scan would halt.
If F2 (Q-Reset) is pressed to reset the coulomb count, a prompt appears asking whether you
want to proceed. To provide a way to respond to the query, F5 is temporarily assigned the
function NO.
7.7. Error Messages
Certain conditions that interfere with normal operation will cause error messages to be displayed
on the LCD panel. The message will give a warning statement about the type of error,
information about the cause (sometimes in a numeric code), and usually advice about what
action to take. Chapter 6, Section 6.11 shows the error messages that could be displayed,
explains their meanings, and describes the actions you should take in response to each.
Another class of error messages can occur in remote-control operation as a result of problems in
setting up or running software on the host computer. These error messages appear on the
computer monitor screen, not the LCD panel. For a discussion of these messages, refer to the
ERR command in the Model 283 Command Set Handbook. Please note that errors indicated on
the LCD panel are hardware errors and are not related to the software error messages that you
can display on the computer monitor with the ERR command.
Chapter 7 — RUNNING POTENTIOSTATIC EXPERIMENTS
49
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Model 283 User’s Manual
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([SHULPHQWV
8.1. Introduction
This chapter shows you how to set the experiment parameters for a galvanostatic experiment
and explains how to run the experiment. In the course of discussion that follows, you will come
across many technical terms specific the Model 283 as well as to potentiostats and galvanostats
in general. Should you encounter an unfamiliar term, or find that the discussion provided in this
chapter isn't sufficiently detailed, please see the Technical Reference in Appendix B. In the
interest of streamlining the procedures chapters, detailed discussions of the parameters and
other technical terms have been grouped into Appendix B, which is alphabetically arranged and
quite thorough.
8.2. Galvanostatic Modes
Under front-panel control, the Model 283 can hold the cell current fixed at a single level during
the experiment, or it can vary the current between three separate programmable levels, called
I lnit, I Mid, and I Final.
The transition between the three levels can be in the form of either a gradual ramp or "scan"
between levels, or a sudden sharp "step." So there are actually a total of three modes of
galvanostatic operation available:
Galvanostatic with constant, non-varying cell current [Galvanostat].
Gavanostatic Scan [Galvanostatic Scan], with a gradual ramp between the three levels of
cell current. You can program the rate of change (“SCANRATE”) of the current between
levels.
Galvanostatic Step [Galvanostatic Step], with sharp steps between the three levels of cell
current.
The lengths of time for which each of the three levels of current are held constant during the
experiment are called T Init, T Mid, and T Final. Each time can be separately programmed (or
omitted entirely).
To run a galvanostatic experiment from the front panel, first set up the basic parameters as
described in Chapter 6. Then, press the MODE key as many times as necessary to display the
menu screen for the galvanostatic mode you wish to use: [Galvanostat], [Galvanostatic Scan], or
[Galvanostatic Step].
After you select the appropriate menu screen, use the PREV and NEXT PARAMETER keys to
display each experiment parameter in turn. The parameters used in each galvanostatic mode are
described in the following sections. More detailed explanations are given in Appendix B. If the
default value of any parameter is not satisfactory for your experiment, use the VALUE knob to
change it.
51
8.3. Setting Cell Current: Special Considerations
It is important to understand that if you change the full-scale current range, the instrument will
automatically reset the cell current to maintain the same ratio of current to full-scale current
range. For example, let's say the full-scale current range is 10 mA and cell current is set to 8.00
mA. Then cell current will be 80% of the full-scale current range. If you decrease the full-scale
current range to 1 mA, this ratio will be maintained automatically and cell current will be reset to
0.800 mA. This is true for any current parameter - CURRENT, I INIT, I MID, and I FINAL.
Note that the value specified for any cell current parameter can be no greater than two times the
full-scale current range selected.
8.4. Setting Cell Current in a Fixed-Current Experiment
The [Galvanostat] menu allows you to set the amount of cell current used in steady-state
galvanostatic operation, where the cell current is held constant. The value for the CURRENT
parameter is that in effect at the time the instrument was last powered down, or the last value set
if changed since power-up. After you have set it as required for your experiment, follow the
directions in Section 8.7 for running your experiment.
8.5. Setting Scanned-Current Experiment Parameters
The [Galvanostatic Scan] menu allows you to set the following experiment parameters for the
Galvanostat Scan mode. In this mode, the Model 283 varies the cell current in a gradual sweep
or ramp between steady-state levels.
I INIT, the cell current during the first steady-state stage of a scan or step sequence.
I MID, the cell current during the second steady-state stage (sometimes called the “vertex”)
of a scan or step sequence.
I FINAL, the cell current during the third steady-state stage of a scan or step sequence.
T INIT, the length of time that I INIT is maintained in the cell.
T MID, the length of time that I MID is maintained in the cell.
T FINAL the length of time that I FINAL is maintained in the cell.
SCANRATE, the rate of change of the cell current between I INIT and I MID, and between I
MID and I FINAL.
CYCLES allows selection of three different scan or step sequences: HALF CYCLE, FULL
CYCLE, and CONTINUOUS. The cycle setting determines the number of separate steadystate. cell current levels that will be used during your experiment.
[email protected] determines the cell current at the end of a scan or step cycle. If you select
OFF, the cell will be turned off (counter electrode connection interrupted) at the end of the
programmed cycle. If you select I INIT, the cell current will be returned (stepped sharply) to I
INIT.
If you select I FINAL, the cell current remains at its last value in the sequence. In the FULL
CYCLE mode, this is I FINAL. But note that in HALF CYCLE operation, the last current level
reached in the sequence actually is I MID.
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Model 283 User’s Manual
Also note that in the CONTINUOUS cycle mode, the experiment doesn't end until the "Stop"
key (F3) is pressed. At that point, the cell current returns to I INIT.
These parameters are explained in greater detail in Appendix B. After you have set them as
required for your experiment, follow the directions in Section 8.7 for running your experiment.
8.6. Setting Stepped-Current Experiment Parameters
In the Galvanostat Step mode, the Model 283 varies the cell current in sharp steps between
steady-state levels. The experiment parameters that can be set from the [Galvanostatic Step]
menu are the same as those set from the (Galvanostatic Scan] menu (see above), except that
there is no SCANRATE setting. After you have set the parameters as required for your
experiment, follow the directions in Section 8.7 for running your experiment.
8.6.1. Introduction
After you have connected your equipment and set all required parameters, you are ready to
begin your experiment. After activating the cell connections (Cell Safety switch and Cell On
key), you will start the experiment and control its progress with the soft function keys, F1
through F5, below the LCD panel.
The functions assigned to these keys in each of the galvanostatic modes are displayed on the
bottom line of the menu screen. These functions are described below. If something goes wrong
and an error message is displayed.
8.6.2. F1 (Coulomb or offset I)
This key selects the parameter to be displayed on the right side of the second line of the menu
screen.
By pressing the F1 key, you can display either of two other parameters on this line: net current
with current offset applied (i) or the final current integral (Q).
Current offset (“I OFFSET”) is a feature that can be used in potentiostatic experiments but is not
useful in galvanostatic operation. Thus there is no provision for setting it from the galvanostatic
menus. But be aware that if you have set a value for I OFFSET in one of the potentiostatic
menus and then switch to galvanostatic operation, the offset will remain in effect when "i" is
displayed.
I OFFSET is a current value that is mathematically subtracted from the cell current before it is
displayed. The result of this subtraction is displayed as "i" and accumulated over time as “Q".
That is, i = I - (I OFFSET), where I OFFSET can have a positive or negative value.
Note that there is no actual current subtraction, only a numerical calculation. Thus current offset
does not affect the potential at the I MONITOR connector.
The final current integral (0) is the net charge, after the algebraic addition of I OFFSET, that has
passed through the cell since the beginning of the experiment while the cell was on (or since the
coulometer was reset). It is expressed in coulombs.
8.6.3. F2 (Q-Reset)
When F2 is pressed, the following quill is displayed on line 3 of the LCD panel:
RESET COULOMBS?...
Chapter 8 — RUNNING GALVANOSTATIC EXPERIMENTS
53
When F2 is pressed, in order to provide a way to respond to the query, F4 is temporarily
reassigned the YES function and F5 the NO function. If you press YES (F4), it resets the
coulometer to zero and reestablishes the initial scaling factor, as set by the selected current
range. If Fl has been used to display 0, you will see the final current integral (in coulombs) on the
second line of the display reset to zero and then begin to increment as charge accumulation
resumes.
If you press NO (F5), the coulometer is not reset and the previous menu screen reappears.
8.6.4. F3 (Start or Stop)
The F3 key is used to start a scan. When it is pressed, the scan progresses as programmed.
After the scan begins, the function assigned to F3 changes to "Stop". Pressing F3 ends the scan
sequence and immediately reestablishes I INIT.
8.6.5. F4 (Hold or Resume)
Pressing the F4 key during a scan causes the scan to temporarily halt. When the key is pressed
again (it will now be labeled "Resume"), the scan resumes.
If a "Hold" occurs when a current is applied to the working electrode, it will continue to be applied
(assuming that the CELL ON key is ON). This is true if the hold takes place at any time during
the scan sequence. The scan simply halts and the current in effect at the moment of the halt
continues to be applied. Time is not counted for the duration of the hold.
If F2 (Q-Reset) is pressed to reset the coulomb count, a prompt appears asking whether you
want to proceed. To provide a way to respond to the query, F4 is temporarily reassigned the YES
function.
8.6.6. F5 (Reverse or Bypass)
In the Galvanostat Scan mode, the F5 key has the "Reverse" function. Pressing F5 during a scan
reverses the direction of the scan.
In the Galvanostat Step mode, the F5 key has a different function: Bypass. Pressing F5 before
or during the programmed T INIT, T MID, or T FINAL delay in the scanning sequence
temporarily overrides that delay and sets it to a minimum (actually 4 ms). The scanning
sequence then immediately advances to the next step. For example, if F5 is pressed during the
T INIT interval, the sequence would immediately advance to the first scan. In half-cycle or
single-cycle scanning, if the next step would advance the sequence to the end of the scan, the
scan would halt. For an explanation of the T INIT, T MID, and T FINAL delays, see Appendix B.
8.7. Error Messages
Certain conditions that interfere with normal operation will cause error messages to be displayed
on the LCD panel. The message will give a warning statement about the type of error,
information about the cause (sometimes in a numeric code), and usually advice about what
action to take.
Please note that errors indicated on the LCD panel are hardware errors and are not related to the
software error codes that you can display on the computer monitor with the ERR command.
54
Model 283 User’s Manual
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9.1. Introduction
In essence, the Model 283 Potentiostat/Galvanostat is a high-current feedback amplifier. This
chapter contains basic circuit descriptions keyed to the simplified block diagrams in Figs. 25, 26,
and 27. Fig. 25 is a simplified block diagram of the 283 operating in the potentiostat mode. Fig.
26 shows the instrument operating in the galvanostat mode. Fig. 27 shows the signal
conditioning circuits that processes the basic analog E and I signals to make possible the
ancillary, control, display, and computer interface functions. These figures also list some of the
commands that affect the indicated circuits. Although there are instances where it may prove
helpful to have this information, keep in mind that only a few commands are listed, and that the
they may well have effects far beyond what can be indicated in these simple diagrams.
The microprocessor incorporated in the instrument allows cell voltage and/or current readings to
be transmitted to a host computer via a GPIB or RS-232 interface, and allows for control of the
system either from the front panel or from a host computer. The program control and data-taking
processes are coordinated so that the resulting data sets can be plotted or otherwise processed
as a function of the applied control program.
9.2. Potentiostat Operation
Fig. 25 illustrates potentiostatic operation. Referring to the figure, first note the Power Amplifier,
which drives the cell's Counter Electrode. The switch between the output of the Power Amplifier
and the Counter Electrode symbolizes the Cell On key and Cell Safety switch. The key to
understanding how the 283 works as a potentiostat is to recognize that it is basically a feedback
amplifier. Several signals drive the summing junction (inverting input) of the Power Amplifier.
Most important of these is the negative feedback from the Reference Electrode to the Power
Amplifier's input. As indicated, there is an electrometer circuit interposed between the Reference
Electrode and the Power Amplifier, necessary because of the Reference Electrode's high input
impedance. Note that there is provision for operating the electrometer differentially or singleended. In single-ended (Hi Stab) operation, the potential at the Reference Electrode is measured
with respect to the ground as supplied to the inverting input of the E Feedback amplifier via
contacts of the indicated switch. In differential (Hi Speed) operation, the potential at the
Reference Electrode is measured with respect to the true sensed potential at the Working
Electrode as supplied to the E Feedback amplifier via the Sense cable.
55
Fig. 25. Simplified Block Diagram of Model 283 in Potentiostatic Mode.
When an input is applied to the Power Amplifier (External Input or DACS), the Power Amplifier's
output applied to the Counter Electrode moves in the opposite direction. For example, applying
+1 V to the input would cause the Counter Electrode to become increasingly negative. As it
becomes more negative, the potential at the Reference Electrode with respect to the Working
Electrode (virtual ground) becomes more negative as well. This Reference Electrode potential is
sensed by the Electrometer and fed back to the summing junction of the Power Amplifier,
countering the effect of the applied input. Because of this negative feedback, the voltage applied
to the Counter Electrode will always assume the level required (within the limitations of the
Power Amplifier's voltage and current capabilities) to maintain zero volts at the summing junction
of the Power Amplifier. This condition is satisfied when the detected Working Electrode potential
equals the net control potential. Thus the Working Electrode potential is controlled at the set or
programmed level. In other words, in potentiostat operation, the potential is controlled and the
cell current at any time is simply determined by the potential of the Counter Electrode and the
analyte characteristics.
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Model 283 User’s Manual
As shown, the net control potential (External Input, when applied, and DACs) is summed with the
Working Electrode potential detected by the Reference Electrode and buffered by the
Electrometer. The Bias DAC sets the background level. The Modulation DAC allows complex
time-varying control programs to be applied.
Provision is made for monitoring the cell current. Another feedback amplifier, the I/E Converter,
which is connected to the cell's Working Electrode, provides this function. A resistance
determined by the selected current range is connected between the output of the I/E Converter
amplifier and its inverting input (buffered). The amplifier output assumes whatever potential it
must to force the inverting input potential to that of the noninverting input (ground). This
requirement is satisfied when the output voltage is I x R volts, where I is the working-electrode
current in amperes and R is the feedback resistance in ohms determined by the current range.
Thus current equal to the selected current range gives full-scale (1 V) output. The I/E Filter
capacitor is also shown.
The output of the I/E Converter is applied to a differential gain-of-one amplifier that provides the
lreport signal at its output. As shown, this signal is made available at the I MONITOR connector,
and is applied to the Signal Conditioning circuits. Note that the Differential Amplifier looks at the
potential difference across the current-range resistor. Producing the lreport signal in this manner
accommodates any potential movement that occurs at the Working Electrode at higher
frequencies where the gain/bandwidth limitations of the I/E Converter come into play.
The Ereport signal is similarly derived. A high common-mode rejection (CMR) amplifier senses
the potential at the Reference Electrode with respect to the Working Electrode to develop the
Ereport signal. This signal is always derived differentially to maintain the highest accuracy at
higher frequencies where the virtual ground at the Working Electrode will "move" as the gainbandwidth limitations of the I/E Converter become a factor.
Also shown in Fig. 25 are the MUX Output circuit, which provides either the E Monitor or I
Monitor signal, ac coupled. Indicated also are the E OUT and I OUT suppression DACs, which
allow the E Monitor and I Monitor signals to be suppressed to zero.
9.3. Galvanostat Operation
In Galvanostat operation (Fig. 26) the basic feedback configuration is changed to make current
the controlled parameter rather than potential. As in potentiostat operation, all of the control
inputs are summed at the input of the Power Amplifier and its output drives the Counter
Electrode of the cell. The significant difference is that it is the Ireport signal at the output of the
I/E Converter that is fed back to the summing junction of the Power Amplifier. As a result, the
system stability conditions are satisfied when the cell current is equal to the selected current
range. The other inputs (Ext Input and DACs) simply shift the cell current with respect to that
established by the selected Current Range.
Note that the electrometer and high CMR amplifier are still available so that the potential of the
working electrode with respect to the reference electrode can still be measured to produce the
Ereport signal, the same as in potentiostat operation. Except that it is optional and is not fed
back to the summing junction of the Power Amplifier, Ereport is distributed the same as in
potentiostat operation.
Chapter 9 — CIRCUIT DESCRIPTION
57
Fig. 26. Simplified Block Diagram of Model 283 in Galvanostatic Mode.
58
Model 283 User’s Manual
9.4. Signal Conditioning
The signal conditioning circuitry is denoted by a block in Figs. 25 and 26 and in greater detail in
Fig. 27. The heart of this circuitry is the multi-line Multiplexer controlled by the SIE command.
This multiplexer makes the selected signal, Ereport or lreport (both filtered or unfiltered), or
selected A/D Input, available for further processing. As shown, the output of the Multiplexer is
routed through some amplifiers to the Gain Calibration DAC, and from there through some
Sample/Hold circuits to the input of the Analog-to-Digital Converter (ADC). The output of the
ADC is a 12 bit representation of the multiplexed signal. This 12 bit code is made available to the
display and to the computer interface circuitry. Note that there is provision for doing suppression
at the output of the Multiplexer.
9.5. Ancillary Functions
9.5.1. E & I Suppression
Figs. 25 and 26 both show the E Out Suppress and I Out Suppress DACS, which generate a dc
suppression voltage in response to the EOUTSUP and IOUTSUP commands and sum it with the
E Monitor and I Monitor outputs.
9.5.2. Auxiliary Inputs
There are two auxiliary inputs on the front panel, called A/D Input 1 and A/D Input 2. Under
control of the AUXSEL command, one of these is selected for and made available to the
Multiplexer as one of the many signals that can be selected by via the SIE command for
acquisition.
9.5.3. Output DACs
There are two Output DACs shown in Fig. 27. One of them drives the OUTPUT connector; the
other the D/A OUTPUT connector. The voltages supplied to these connectors are developed by
the Output DACs in response to the SETOUT and SETOUT2 commands as discussed in the
Command Set Handbook. These dc outputs can be used to control the speed of a Model 616 or
636 Rotating Electrode or put to other use.
Chapter 9 — CIRCUIT DESCRIPTION
59
Fig. 27. Simplified Block Diagram of Signal Conditioning Circuitry.
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Model 283 User’s Manual
0DLQWHQDQFHDQG6HUYLFH
10.1. Introduction
The Model 283 Potentiostat/Galvanostat has been designed for optimum reliability, and requires
no periodic maintenance except for battery replacement.
10.2. Battery Replacement
After several years of use, the internal battery may require replacement. The Model 283 is
equipped with a long-life lithium battery to retain the calibration settings in memory. The battery
has a life of approximately two to five years, depending on how much you use the instrument.
You cannot replace the battery yourself; you must send the instrument to an authorized PARI
repair facility for battery replacement.
When the battery needs replacement, the instrument will alert you with a message on the frontpanel LCD display. Note that you can use the instrument without the battery, but if you do, you
will have to recalibrate the instrument every time you power up.
10.3. Service
This manual contains no service information, as there are no operator-serviceable parts inside
the Model 283. The instrument is very difficult to service in the field; special fixtures and services
are required that are not readily obtainable except at the factory or at certain affiliate facilities.
Contact the factory service department or the affiliate in your area if service is required.
61
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Model 283 User’s Manual
$33(1',;$6SHFLILFDWLRQV
Power Amplifier
Compliance Voltage: > ±80 V
Maximum Output Current: > ±100 mA
Rise Time: < 300 ns
(1 V, unity gain, no load, 10% - 90%)
Slew Rate: 10 V/µs
Bandwidth (Unity Gain, 1 k load): >1.5 MHZ
Voltage Temperature Stability: < 50 µV/deg C
Differential Electrometer
Input Impedance: > 1013 (1014 typ) in parallel
with 5 pF (1 pF typ)
Input Bias Current: <10 pA at 25(C
Maximum Input Voltage
Differential: ±12 V no damage, either input
Common Mode Rejection
>80 dB at 100 Hz
>60 dB at 1 MHZ
Bandwidth (1 k source resistance, -3 dB,
small signal): >9 MHZ
Offset Voltage: <100 µV
Offset Temperature Stability: <50 µV/deg C
iR Compensation
Positive Feedback
Range: 2 G to 20 depending on current range
Resolution: 0.05% of current range
Current Interrupt
Digital Potential Error Correction: 12 bit DAC
Total Interruption Time: 10 µs to 2000 µs
Current Measurement
Ranges: 9 decades, 100 mA to 1 nA
Accuracy @ I MONITOR connector
100 nA to 100 mA Ranges: 0.2% of full scale
1 nA and 10 nA Ranges: 2% of full scale
Frequency Response (Small Signal)
1 mA Range: -3 dB at >2 MHZ, 1 k
1 µA Range: -3 dB at >200 kHz, 1 M
Potential/Current Control
Bias Digital/Analog Converter (DAC)
Resolution: 14 bits
Range (Potentiostat): ±8 V
Modulation Digital/Analog Converter (DAC)
Resolution: 16 bits
Range (Potentiostat): ±8 V, ±0.8 V, and ±0.08 V
Range (Galvanostat): ±200%, ±20.00%, and
±2.000% of Full-Scale current
Accuracy
Applied Potential: 0.2% of reading ±2 mV
Applied Current: 0.2% of Full-Scale current
System
Applied Voltage Noise (0.1 Hz to 100 kHz): 25 µV rms
Drift:
vs temp: <µV 50 /(C
vs time: <200 µV/week
Computer Interfaces
RS-232C
IEEE 488.1-1987 with the following interface functions
implemented: SH1, AH1, T6, L4, SR1 RL1, PP0, DC1,
DT0, C0, E2
Weight
18.2 kg (40 lb)
Size
17.0" W x 10.3" H x 20.0" D
Power Requirements
90130 VAC or 210260 VAC, 5060 Hz
Ambient Temperature Range
Specifications apply from 20(C to 30(C
Instrument will operate from 10(C to 40(C
63
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Model 283 User’s Manual
$33(1',;%7HFKQLFDO5HIHUHQFH
B.1. Introduction
This reference comprises an alphabetical list of all the experiment setup parameters and commands
that can be programmed from the front panel of the Model 283, with detailed explanations of each.
Although you may wish to read through it in its entirety to become more familiar with the Model 283
and its operation, this material is particularly well suited to use as a convenient reference.
B.2. Front-Panel Parameters and Commands
Address
See GPIB Address.
Automatic Current Ranging
See Current Auto-Ranging; Current Range.
Bandwidth (Stability versus Speed)
Bandwidth is set from the FUNCTION menu screen. One of the two bandwidth modes, HI SPEED or
HI STABILITY, will always be in effect. The default setting is HI STABILITY. The speed vs stability
tradeoff is achieved by operating with the electrometer configured single-ended (HI SPEED) or
differentially (HI STABILITY) as discussed in Chapter 9.
The HI SPEED mode gives the fastest response in Potentiostat or Galvanostat operation, but without
guaranteed stability in all experiments. Under the proper conditions with certain cells, ringing almost
always occurs and oscillations may occur. Cells having large capacitance and low resistance are
most likely to prove troublesome.
The HI STABILITY mode provides extreme stability at somewhat reduced speed. In this mode, stable
operation is assured with virtually any cell. However, the possibility always exists that with an
unfamiliar cell configuration, or under extremely unusual operating conditions, stability problems
might occur. If oscillation does occur in the HI STABILITY mode, the cause may be too much
resistance in the reference electrode. Even a well-designed, low- impedance reference electrode can
develop a high resistance if salts precipitate in the junction.
Baud Rate
See Serial Baud Rate.
Cell (Condition) at End
This parameter, set from the scan or step experiment menu screens, determines the working
electrode potential (in potentiostatic operation) or cell current (galvanostatic operation) at the end of a
scan or step cycle. If you select OFF (the default setting), the cell will be turned off (counter electrode
connection interrupted) at the end of the programmed cycle. If you select E INIT (I INIT in
galvanostatic operation), the working electrode potential (or cell current) will be returned to E INIT (or
I INIT).
If you select E FINAL (or I FINAL), the working electrode potential (or cell current) remains at its last
value in the programmed scan sequence. In the FULL CYCLE mode, this is E FINAL (or I FINAL).
But note that in HALF CYCLE operation, the last level reached in the sequence actually is E MID (or I
MID).
Also note that in the CONTINUOUS cycle mode, the experiment doesn't end until the "Stop" key (F3)
is pressed. At that point, the cell status returns to E INIT (I INIT in galvanostatic operation).
65
Cell Current
Cell current is the controlled parameter in galvanostatic operation. In steady-state galvanostatic
operation, where the cell current is held constant, the CURRENT parameter is set from the
[Galvanostat] menu screen. The value for CURRENT is that in effect at the time the instrument was
last powered down, or the last value set if changed since power-up. The units and resolution are
indicated by the display.
Current parameters I INIT, I MID, and I FINAL, set from the [Galvanostatic Scan) and [Galvanostatic
Step] menu screens, specify the cell current at each of three stages in a scan or pulse sequence. I
INIT specifies the current at the start of the scan. I MID specifies the current at end of the scan's first
leg. In Half Cycle made operation, the scan ends at I MID, and I MID continues to flow in the cell.
In Full Cycle operation, I MID is a vertex and I FINAL specifies the final current which continues to
flow after the scan is over. In Continuous Cycle operation, there is repetitive cycling between I MID
and I FINAL until the STOP key (F3) is pressed. Delays T INIT and T MID may be used to determine
the length of time I INFT and I MID are in effect (PASS = 4 ms). The Delay at I INIT and I MID may
be carried out with the cell either on or off. See Delays for details.
It is important to understand that if you change the full-scale current range, the instrument will
automatically change the cell current to maintain the same ratio of current to full-scale current range.
For example, let's say the full-scale current range is 10 mA and cell current is set to 8.00 mA. Then
cell current will be 80% of the full-scale current range. If you decrease the full-scale current range to 1
mA, this ratio will be maintained automatically and cell current will be reset to 0.800 mA. This is true
for any current parameter CURRENT, I lNIT, I MID, and I FINAL.
Keep in mind that the value specified for any cell current parameter can be no greater than two times
the full-scale current range selected.
Cell Potential
E INIT, E MID, and E FINAL specify the potential applied at each of three stages in a scan or pulse
sequence. Potential is the controlled parameter in Potentiostat mode operation. E INIT specifies the
potential applied at the start of the scan. E MID specifies the potential applied at end of the scan's
first leg. In Half Cycle mode operation, the scan ends at E MID, and E MID continues to be applied.
In Full Cycle operation, E MID is a vertex and E FINAL specifies the final potential, which continues
to be applied after the scan is over. In Continuous Cycle operation, there is repetitive cycling between
E MID and E FINAL until the "Stop" key (F3) is pressed. Delays T INIT and T MID may be used to
determine the length of time E INIT and E MID are applied (PASS = 4 ms). The Delay at E INIT and
E MID may be carried out with the cell either on or off. See Delays for details.
In steady-state potentiostatic operation, where the potential at the working electrode is held constant
with respect to the reference electrode, the Potential parameter is set from the [Potentiostat] menu
screen. In steady-state operation, the value for the Potential parameter is that in effect at the time the
instrument was last powered down, or the last value set if changed since power-up.
The units and resolution are indicated by the display. Potential can be specified to the nearest mV.
Potentials can be set over a range of -10 V to +10 V. However, the absolute potential range, that is,
the difference between the highest potential in an experiment and the lowest potential in that same
experiment, cannot exceed 8 V.
Current Cell
See Cell Current.
Current Auto-Ranging
In potentiostatic operation, you can allow the Model 283 to automatically set the appropriate full-scale
current range. In the Auto-Ranging mode, selected by pressing the AUTO key, the Model 283
automatically seeks the full-scale current range that causes the I MONITOR potential to be between
15% and 190% of full scale; that is, between 150 mV and 1.9 V. If cell current is less than 150 nA,
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Model 283 User’s Manual
the 100 nA range will be selected. If the instrument is on the 10 mA range and cell current is greater
than 19 mA, the 100 mA range will be selected. This process occurs after each point is acquired, with
the constraint that it can only change one range at a time. Data could be lost if the data amplitude
changed faster than it could be tracked by the auto-ranging function. For an explanation of the fullscale current range, see Current Range, Full Scale.
You can set a limit to the automatic current ranging by adjusting the I AUTO LIMIT parameter on the
[System Default] menu (see Chapter 6, Section 6.7B). The full-scale current range will not go below
the I AUTO LIMIT you set. The default range is 100 nA.
Note that automatic current ranging is restricted to operation in the Potentiostat mode. It cannot be
selected in the Galvanostat mode.
Current Integral (Coulombs) Display
In the potentiostatic and galvanostatic experiment menu screens, the Fl key selects the parameter to
be displayed on the right side of the second line of the menu screen.
By pressing Fl, you can display either of two other parameters on this line: net current with I OFFSET
applied (i) or the final current integral (Q).
I OFFSET is a current value that is mathematically subtracted from the cell current before it is
displayed. The result of this subtraction is displayed as “i” and accumulated over time as "Q". That is,
i = I - (I OFFSET), where I OFFSET ran have a positive or negative value.
Note that there is no actual current subtraction, only a numerical calculation. Thus current offset does
not affect the potential at the I MONITOR connector.
Current offset is a feature that ran be used in potentiostatic experiments but is not useful in
galvanostatic operation. Thus there is no provision for setting it from the galvanostatic menus. But be
aware that if you have set a value for I OFFSET in one of the potentiostatic menus and then switch to
galvanostatic operation, the offset will remain in effect when "i" is displayed.
The final current integral (Q) is the net charge, after the algebraic addition of I OFFSET, that has
passed through the cell since the beginning of the experiment while the cell was on (or since the
coulometer was reset). R is expressed in coulombs. In the FULL FRILLS acquisition mode (see the
Command Set Handbook for a discussion of the acquisition modes), the displayed charge
accumulation will be updated every timebase. Q normally is not selected if speed of data acquisition
is the main concern, such as might be the case when the Model 283 is being controlled from an
external computer via the RS-232 or GPIB interface.
When you press the F2 key (Q Reset), the following query is displayed on line 3 of the LCD panel:
RESET COULOMBS?...
If you press YES (F4), it resets the coulometer to zero and reestablishes the initial scaling factor, as
set by the selected current range. If Fl has been used to display Q, you will see the final current
integral (in coulombs) on the second line of the display reset to zero and then begin to increment as
charge accumulation resumes.
If you press NO (F5), the coulometer is not reset and the previous menu screen reappears.
In a perfect instrument and cell system, Q of course could not change when the cell is disconnected,
because no cell current would flow. But in a real system, no matter how precise, some small charge
may appear as a result of drift and other circuit variations. Thus, setting UPDATE Q W/CELL OFF =
NO (from the [System Default] menu) prevents charge from accumulating when the cell is off.
Choosing YES allows it to accumulate, and might help to estimate drift errors.
APPENDIX B — TECHNICAL REFERENCE
67
Current Interrupt iR Compensation
Current Interrupt is one of two available iR Compensation techniques (see iR Compensation). iR
Compensation can be selected from any of the three potentiostatic menu screens (IR MODE). The
default setting is OFF.
iR Compensation is used to eliminate the error caused by the iR drop across the uncompensated
resistance in the electrochemical cell. The Current Interrupt technique does this by rapidly shutting off
the cell current, estimating the drop in reference potential before the cell double-layer capacitance
discharges through RP (the polarization resistance), and then adding that iR drop back into the
counter electrode control voltage.
When the current in the cell is interrupted, a drop in the E MONITOR potential equal to iRU occurs.
As this potential drop cannot be measured directly, it is estimated by extrapolation from two other
potential levels measured at specified intervals after current interruption.
Four parameters, all available from the potentiostatic menu screens, can be adjusted to estimate and
fine-tune the amount of iR compensation to be applied. IRUPT (Intermittent Current Interrupt) sets the
interval between current interrupts. The range is 1 to 32767 data points, with a default setting of 5
points. In local operation from the front panel, 5 points is equivalent to 20 ms if LINE SYNC is not
enabled. (In remote control from a host computer, the interrupt timing is controlled by the computer.)
IRUPT T1 sets the increment of time between the interruption of current to the cell and the first
sampling of potential during the no-current condition. IRUPT T2 sets the time increment from IRUPT
T1 to the second sampling of potential. These two potential levels, at IRUPT T1 and IRUPT T2, are
used to extrapolate the value of the iR drop across the uncompensated resistance in the cell.
The IRUPT T1 and IRUPT T2 settings can range from 10 µs to 2000 µs, but the sum of the values of
IRUPT T1 and IRUPT T2 may not exceed 2000 µs. The default values for both are 10 µs on the 100
mA current range and 75 µs on all other current ranges. Note that IRUPT T1 and IRUPT T2 can be
set independently for each current range.
IRPC (Current Interrupt Percent Correction) sets the percentage of correction, adjustable from 0% to
200%, with a default of 100%. This function is used to fine-tune the extrapolation procedure.
Note: The default values of these parameters give good results in many applications. Do not change
them unless you are well versed in current-interrupt iR compensation theory. This is particularly true
of IRUPT T1, IRUPT T2, and IRPC.
A prerequisite to evaluating these parameter selections is that an oscilloscope be connected to the E
MONITOR BNC connector to observe the current-interrupt waveform, as discussed in the following
paragraphs. Even with the oscilloscope, it is not easy to make optimum determinations. The position
of the selected points, as well as the path of the projection through the points, must be estimated.
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Model 283 User’s Manual
Fig. 28. Current Interrupt Waveform At E Monitor
Connector.
Fig. 28 illustrates the E MONITOR waveform for a typical Current Interrupt cycle. Referring to the
figure, note that a fast potential drop equal to iRU occurs at the moment of interrupt. The purpose of
the current interrupt procedure is to estimate this potential drop so that a correction factor can be
developed. As the drop cannot be measured directly, it is estimated by extrapolation from two
potential levels measured later at different points on the curve of potential decay after current
interruption.
Just before current interruption, the potential level is sampled. After interrupt, two more potential
samples (at IRUPT T1 and T2) are taken. The operator specifies the time intervals between the
current interruption and the second sample (IRUPT T1), and between IRUPT T1 and the third sample
(IRUPT T2). Each time interval must be at least 10 µs.
The potential levels at IRUPT T1 and T2 are used to define a projection that is extrapolated back to
the instant just after current interruption. By comparing the linearly extrapolated potential at that
instant with that before the interruption (the first sample), a correction function is developed that
corrects for the uncompensated iR drop in the cell.
The goal is to select two points for IRUPT T1 and T2 that will provide a projection that intersects the
lower end of the iRU drop. If the intersection occurs at a higher point, the correction factor will be too
small. If it occurs at a lower point, as is the case for the example depicted in the figure, the correction
factor will be too large.
Two general guidelines can be used for setting IRUPT Tl and IRUPT T2:
1.
T1 should be greater than cell cable capacitance (about 20 pf) x RU (often on the order of
1000 ). Assuming these values, IRUPT T1 should be greater than 20 ns. But RU may be
considerably higher than 1000 when you are working with low-conductivity media, such as
concrete or nonaqueous solvents.
2.
T2 should be less than cell capacitance (generally around 25 µF/cm2) x RU (as determined from a
polarization resistance experiment).
APPENDIX B — TECHNICAL REFERENCE
69
Fortunately, IRPC, by allowing user control of the percentage of correction, eases the point selection
task. For example, if the extrapolated line were to intersect exactly halfway down the drop, the
correction factor would be 50% of the required value. The resulting correction factor could be easily
adjusted to its proper value by using IRPC to set the percentage of correction to 200%. Similarly, if
the intersection occurred below the drop, as in the depicted example, IRPC would be used to set a
percentage of correction of less than 100% (90% would be about right for the example).
Once Current Interrupt iR Compensation is established by setting IR MODE = IRUPT, and IRUPT T1,
IRUPT T2, IRUPT, and IRPC are set, no other operator intervention is required during the
measurement.
Current Interrupt iR Compensation has several advantages as compared to Positive Feedback iR
Compensation:
1.
This technique corrects for essentially the entire potential error caused by the uncompensated
resistance.
2.
This technique corrects for any changes in the uncompensated resistance as the scan
progresses.
3.
No adjustment is required on the part of the user. The only action required is the simple selection
of IR MODE = IRUPT. (The default values of IRUPT T1, IRUPT T2, IRUPT, and IRPC will give
good results in many applications.)
Disadvantages of the technique include:
1.
The correction occurs at finite times. Thus the technique is not suitable for scan rates greater
than 500 mV/s and may, in fact, not work properly at scan rates greater than 100 mV/s.
2.
If the correction isn't updated frequently enough, the applied correction can be in error.
3.
In some cases, this technique can cause the entire system to oscillate.
Note that Current Interrupt is a positive feedback technique which reduces the margin of stability in
the control of the cell. Slow scan rates reduce this problem by allowing the potentiostat loop to fully
settle before the next interruption.
Note: If the cell is turned OFF while current interrupt is selected, the current interrupt routine is
skipped and no correction occurs. When the cell is turned back on, the current-interrupt routine
resumes.
Once Current Interrupt Compensation is running, the user may wish to monitor the waveform at the
E MONITOR connector with an oscilloscope to optimize the Current Interrupt parameters as
established by IRUPT T1, IRUPT T2, IRUPT, and IRPC. The selection of the extrapolation points (T1
and T2) and the Percent Correction (IRPC) setting determine the accuracy of the applied correction.
Note that the waveform depicted in Fig. 28 is idealized; actually encountered waveforms may not be
so easy to analyze.
Current Offset (I Offset)
Available at the three potentiostatic operation menus, I OFFSET allows you to specify a current value
to be mathematically subtracted from the cell current before ft is displayed. The result of this
subtraction is displayed as "i" and accumulated over time as "Q". That is, i = I - (I OFFSET), where I
OFFSET can have a positive or negative value.
Note that there is no actual current subtraction, only a numerical calculation. Thus current offset does
not affect the potential at the I MONITOR connector.
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Model 283 User’s Manual
The offset range is ±2 times the selected full-scale current range. It you change the current range, the
instrument will automatically reset I OFFSET to maintain the same ratio of current offset to full-scale
current range.
Current Overload
The I OVERLOAD indicator lights if the cell current exceeds two times the selected full-scale current
range. This does not mean that the cell control loop is out of control. It means only that the cell
current monitoring circuits are being driven to the limit.
Current Range, Full Scale
The full-scale current range selection is used to scale the output potential at the I MONITOR
connector to a useful value for any cell current. A cell current equal to the selected current range
gives 1 V at the I MONITOR connector. Note that a current that exceeds two times the current range
generates an I OVERLOAD condition.
The polarity of the voltage at the I MONITOR connector is that of the current. For example, a current
level of -1 mA will give -1 V at the I MONITOR connector (1 mA Current Range), representing an
anodic or reducing current.
The full-scale current range can be set either manually by the operator or automatically by the Model
283 (“Auto-Ranging”). But note that Auto-Ranging is restricted to potentiostatic operation. Should the
user attempt to select Auto-Ranging in galvanostatic operation under remote control, an error
message will be generated. In local control, no error message will be generated but the AUTO key
will be ignored.
In the Manual ranging mode, selected by toggling the AUTO key to turn the AUTO indicator off, the
current range is selected with the arrow keys below the current range indicators. The key moves
the selection upwards through the available ranges. The key moves it downwards.
In the AUTO mode, selected by pressing the AUTO key, the Model 283 automatically seeks the fullscale current range that causes the I MONITOR potential to be between 15% and 190% of full scale;
that is, between 150 mV and 1.9 V. If cell current is less than 150 nA, the 100 nA range will be
selected. If the instrument is on the 10 mA range and cell current is greater than 19 mA, the 100 mA
range will be selected. This process occurs after each point is acquired, with the constraint that it can
only change one range at a time. Data could be lost if the data amplitude changed faster than it could
be tracked by the auto-ranging function.
You can set a limit to the automatic current ranging by adjusting the I AUTO LIMIT parameter on the
[System Default] menu (see Chapter 6, Section 6.7B). The full-scale current range will not go below
the I AUTO LIMIT you set. The default range is 100 nA.
The I/E Filter (if selected) can cause unpredictable effects on your experiment d AUTO current
ranging is in use. If I/E FILTER = ON is selected (from the [System Default] menu screen), you
generally should use manual current ranging.
Current Ranging, Automatic
See Current Auto-Ranging.
Cycle Control
The CYCLES parameter, set from the [Potentiostatic Scan], [Potentiostatic Step], [Galvanostatic
Scan], or [Galvanostatic Step] menu, determines the number of separate steady-state potential levels
that will be used at the working electrode (or steady-state cell current levels in galvanostatic
operation), during your experiment. Three different cycle sequences are available: HALF CYCLE,
FULL CYCLE, or CONTINUOUS. A brief description of each setting follows.
APPENDIX B — TECHNICAL REFERENCE
71
1.
HALF CYCLE: This is the simplest cycle, involving only two potential or current settings. A halfcycle sequence proceeds as follows.
a. Delay T INIT at E/I INIT.
b. Scan (or step) from E/I INIT to E/I MID.
c. Scan remains at E/I MID for T MID, then stops.
At the end of the scan or step sequence, the setting of [email protected] on the menu will determine
whether cell potential or current will remain at its last value ([email protected] = E FINAL or I FINAL),
will step to E INIT or I INIT, or will step to OFF (counter electrode connection interrupted).
Note that the setting of [email protected] = E FINAL or I FINAL will cause cell potential or current to
remain at the last level it reached in the experiment sequence, which in half-cycle operation
actually is E MID or I MID.
2.
FULL CYCLE: A Full Cycle is more complex and involves all three programmed potential or
current levels. The sequence is:
a. Delay T INIT at E/I INIT.
b. Scan (or step) from E/I lNIT to E/I MID.
c. Delay T MID at E/I MID.
d. Scan (or step) from E/I MID to E/I FINAL.
e. Scan remains at E/I FINAL for T FINAL, then stops.
At the end of the scan or step sequence, the setting of [email protected] on the menu will determine
whether cell potential or current will remain at E/I FINAL, will step to E/I INIT, or will step to OFF
(counter electrode connection interrupted).
3.
CONTINUOUS: Continuous is the most complex of the three cycles. The sequence is as
follows.
a. Delay T INIT at E/I INIT.
b. Scan (or step) from E/I INIT to E/I MID.
c. Delay T MID at E/I MID.
d. Scan (or step) from E/I MID to E/I FINAL.
e. Delay T FINAL at E/I FINAL.
f. Scan (or step) from E/I FINAL to E/I MID.
g. Steps 3 through 6 repeat until “Stop” key is pressed.
Automatic cycling of the scan back and forth between E/I MID and E/I FINAL will continue until
you press the “Stop” key (F3). When it is halted, the cell potential or current will step sharply to
E/I INRT, ending the cycling.
Data Bits
See Serial Data Bits.
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Model 283 User’s Manual
Delays T lnit, T Mid, T Final
A delay is a time interval between rampwise or stepwise changes in cell potential or current. The
cell potential or current does not change during a delay. Delays are programmed from a "Scan"
or "Step" menu, and can be set at three different points (T INIT, T MID, and T FINAL) in the scan
or step sequence. Each delay can range from 4 ms to 500 s.
Scans typically, but not necessarily, begin with a delay. The first delay interval, T INIT, precedes
the first leg of the scan or step. It begins when you press "Run" (F3). The cell potential or current
during T INIT is determined by the setting of E/I INIT. If E/I INIT is not zero, the cell potential or
current steps sharply to the specified level. Once the delay interval ends, the scan begins and the
potential or current begins to increment as programmed.
In full-cycle or continuous operation, a second delay, T MID, can be interposed between the first
and second legs of the scan. The cell potential or current is determined by the setting of E/I MID.
In continuous operation only, a third delay, T FINAL, can be interposed between the second and
third legs of the scan. The cell potential or current is determined by the setting of Ell FINAL.
In [Potentiostatic Step] or [Galvanostatic Step] operation, you may temporarily override a
programmed T INIT, T MID, or T FINAL delay by pressing "Bypass” (F5). Pressing F5 before or
during the delay temporarily overrides that delay and sets it to a minimum (actually 4 ms). The
scanning sequence then immediately advances to the next step.
For example, if "Bypass" F5 is pressed during the T INIT interval, the sequence would
immediately advance to the first scan. In half-cycle or single-cycle scanning, if the next step
would advance the sequence to the end of the scan, the scan would halt.
Dummy Cell
See Cell Type.
E Initial, E Mid, E Final
See Cell Potential.
E Overload
The E OVERLOAD indicator lights if the control amplifier output is at its limit (Econtrol > 80 V) and
the control loop is not controlling the cell potential. This can happen in either Potentiostatic or
Galvanostatic operation and normally indicates either a cell-setup problem or an extremely high
resistance solution.
Whenever E OVERLOAD lights, the problem must be located and corrected before valid
measurements can be made. A common cause in potentiostatic operation is a disconnected
reference electrode. Note that this can cause damage to the working electrode if it occurs.
Echo
See GPIB Echo; Serial Echo.
External Input
The EXT INPUT connector has two separate but similar functions: External Input and Oscillator
Input. The main difference between these functions is that in the OSC IN mode the gain of the
applied signal can be scaled up or down, while the EXT INPUT mode always applies unity gain to
the input signal.
This connector can be made active (turned on) or inactive either with the front panel controls or
by software commands from an external computer. From the front panel, it can be controlled with
either the EXT INPUT or the OSC IN setting on the [System Default] menu (see "Adding an
External Signal", Section 6.13). Remote control from an attached computer is described in the
APPENDIX B — TECHNICAL REFERENCE
73
Model 283 Command Set Handbook. Note that both EXT INPUT and OSC IN cannot be set to
ON at the same time.
When the EXT INPUT connector is active (“ON”), an analog control voltage applied to it will be
summed with the output of the digital-to-analog converters (DACs), which are set at the front
panel or from an attached PC. The control signals could be generated by, for example, a PARI
Model 175 Universal Programmer to provide rapid scanning and true analog cyclic voltammetry.
Other waveform generators, a lock-in amplifier, or a frequency response analyzer could be used.
In potentiostatic operation, all of the control potentials add algebraically. For example, if the
voltage applied to EXT INPUT is +0.5 V, at a time when a potential of +0.5 V is programmed in
the instrument, the net potential applied will be +1.0 V, and the working electrode would be
controlled at +1.0 V with respect to the reference electrode. (This assumes, of course, that the
applied signal is not scaled by selecting the OSC IN mode.) A positive applied potential will
make the current tend to be more anodic. A negative applied potential will make the current tend
to be more cathodic.
In galvanostatic operation, making the applied potential more positive by any means except
applying a potential to the EXT INPUT connector will tend to make the cell current more
cathodic. Making the applied potential more negative will tend to make the current more anodic.
This sense is reversed at the EXT INPUT connector. There, making the input more positive will
make the cell current more anodic. Making the input more negative will make the cell current
more cathodic.
Extrapolation Points
See Current Interrupt iR Compensation.
Filters
You can switch in two low-pass filters by setting I/E FILTER = ON from the [System Default]
menu screen. Note that you cannot select only one filter at a time; both must be either selected
at the same time or bypassed. Both filter the signal input to the A/D converter. One of these
filters has a sharp cutoff at 5.3 Hz. (In remote operation, a 590 Hz low-pass filter is also available
under software control.)
The second low-pass filter selected by setting I/E FILTER = ON consists of a roll-off capacitor
that reduces the bandwidth of the I/E converter. The effect of this capacitor on bandwidth
depends on the current range selected.
Unlike the 5.3 Hz filter, the roll-off capacitor filters the signal at the I MONITOR connector. This
capacitor is often helpful when making low-current measurements on large electrodes because it
reduces the noise at I MONITOR. The disadvantage of using the filter is that the I MONITOR
response time is degraded.
As the effect of the roll-off capacitor on the I/E converter bandwidth varies with the current range,
filtering can cause unpredictable effects if AUTO current ranging is in use. If I/E FILTER = ON is
selected, we recommend manual current ranging.
It may be advantageous to synchronize data acquisition with the power line frequency when
filtering. This can be done by setting LINE SYNC = ON (see “Line Sync”).
Full-Scale Current Range
See Current Range, Full Scale.
GPIB Address
The IEEE 488-1978 Instrument Bus Standard defines a bit-parallel, byte-serial bus structure
designed to allow communications between intelligent instruments. Using this standard, many
instruments may be interconnected and remotely controlled or programmed. Data can be taken
from, sent to, or transferred between instruments via one connector or port.
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Model 283 User’s Manual
Each device on a shared GPIB bus is assigned a listen address and a talk address for
identification. These addresses are set at the device. When the controller (the PC) wishes to
communicate with a specific device (the Model 283) on the bus, it places the listen address of the
device on the bus. Only the device having the corresponding address will respond to the
subsequent message. Similarly, if the controller wants a device to talk, it sends the talk address
of the device in question. The addressed device will transmit until a different talker is designated.
When the controller communicates with a device on the bus, it begins by placing the address of
that device on the bus with ATN asserted. Naturally, each device must “know” its own TALK and
LISTEN address. In the case of the Model 283, these addresses are set from the [System
Interface] menu on the front panel with the VALUE knob.
The Model 283 can be set for any address from 1 to 30. The normal address setting for use with
PARI software is 14. See your software manual for its individual requirements.
Further details of GPIB addressing are given in the appendixes of the Model 283 Command Set
Handbook.
GPIB Terminator Character
In GPIB communications, the terminator is the character that marks the end of each transmission
from the Model 283 to the host computer or from the host computer to the Model 283. It must be
selected on the Model 283 according to the requirements of the host computer, sometimes in
conjunction with the software it is running. Failure to satisfy this requirement is one of the most
common causes of problems in establishing communications via the GPIB.
You set the terminator from the [System Interface] menu on the Model 283 for GPIB
transmissions to the host computer. When the terminator is set to "CR”, it is a Carriage Return.
When the terminator is set to "CRLF", it is a Carriage Return followed by a Line Feed. The
terminator required for GPIB communications with IBM PC-compatible computers running PARI
software is CR.
Note that you cannot configure the Model 283 to receive transmissions ended by the CRLF
terminator. The Model 283 always expects the OR terminator in data it is receiving via the GPIB
bus.
GPIB Test Echo
A special GPIB TEST ECHO mode can be established by switching to the [System Interface]
menu and setting GPIB ECHO = ON. When the Test Echo function is ON, every character
transmitted or received via the GPIB port will be echoed to the RS-232 interface connector. The
RS-232 baud rate should be high to prevent slowing down the GPIB.
This feature is particularly useful when developing programs. If a "dumb" CRT terminal is
connected to the RS-232 interface, the programmer will see all communications on the CRT.
Such a terminal will allow direct interaction, thereby facilitating the programmer's understanding
of the commands and responses. In addition, the programmer will be able to monitor the
program data and intervene if necessary.
During normal operation, GPIB ECHO should be set to OFF.
High-Speed Mode
See Bandwidth.
High-Stability Mode
See Bandwidth.
I Initial, I Mid, I Final
See Cell Current.
APPENDIX B — TECHNICAL REFERENCE
75
I Offset
See Current Offset
I Overload
See Current Overload.
iR Compensation
In an electrochemical experiment, the voltage across the double layer of the specimen surface
must be closely controlled. If you don't have confidence that the potential you're applying is the
potential felt at the specimen, you can't be sure that your measurement is valid.
But there are factors which make it difficult to control this potential. In all electrochemical cells
there is some resistance between the tip of the reference electrode and the outside of the double
layer of the specimen surface. This resistance is referred to as the "uncompensated resistance."
As current flows through the electrochemical cell, a potential is developed across the
uncompensated resistance. When the uncompensated resistance gets high (as it does in pure
water or organic solvents, for example) or the current becomes large, a significant potential error
may occur.
Obviously, it is desirable to eliminate this error. The Model 283 provides two techniques for this:
Positive Feedback iR Compensation (PFIR) and Current Interrupt iR Compensation (IRUPT).
The voltage at the E MONITOR connector is corrected when either technique is employed.
Both iR Compensation techniques can be set from any of the three potentiostatic menu screens.
Only one iR Compensation mode can be active at a time. If one of the two is active and the
other is selected, the one previously active will be turned off and the newly selected mode will
become active.
The two iR Compensation techniques are performed in entirely different ways. Because each of
the techniques has strengths and weaknesses, some situations will call for one technique and
some for the other. Fig. 29 briefly lists the relative strengths of the two techniques.
For details of the two techniques, see Current Interrupt iR Compensation; Positive Feedback
iR Compensation. A more complete discussion of iR Compensation can be found in "Technical
Note 101," available on request from PARI.
Fig. 29. Comparison of Positive Feedback and Current Interrupt iR
Compensation.
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Model 283 User’s Manual
iR Mode
See iR Compensation; Current Interrupt iR Compensation; Positive Feedback in iR
Compensation
IRUPT
See Current Interrupt iR Compensation.
Knob Timeout
To prevent someone from changing an experiment parameter by inadvertently moving the
VALUE knob, you can disable the knob after you have finished using it. You can specify the
period of time R waits after its last use before becoming inactive (the “timeout” period). At the
end of the timeout period, the knob will have no effect on parameter settings, and the LCD panel
will display "KNOB TIMEOUT HIT ANY KEY." Press any key to reactivate the knob. The KNOB
TIMEOUT parameter is set from the [System Interface] menu screen.
Line Sync
The LINE SYNC parameter, set from the [System Default] menu screen, determines whether
data acquisition will be synchronized with the power line frequency. If you set it to YES, samples
are taken every 16.6 ms (60 Hz power) or every 20 ms (50 Hz power), If you set it to NO,
samples are taken at the rate determined by the internal time base. The default state of this
parameter is NO.
If the LINE SYNC setting is changed while a scan is in progress, the scan will proceed at the new
rate.
Note: In P-Scan, if the scan rate is >250 mVIs, Line Sync cannot be enabled. Conversely, if
Line Sync is enabled, the scan rate will not increase beyond 250 mV/s. A similar interaction
applies to G-Scan, where Line Sync is incompatible with scans faster than 25% of f.s. range per
second. For example, on the 100 µA range, the fastest scan rate possible with Line Sync enabled
would be 25 µA per second.
Osc In
Set from the [System Default] menu screen, the OSC IN parameter setting determines whether
the front-panel EXT INPUT connector will accept and scale an applied signal. Use ON if the
applied signal is too large or too small and you wish to scale it by a factor of 0.02, 0.2, or 2.0.
OFF is used either when no signal is to be applied, or when an applied signal is of a useful
amplitude with unity gain (in that case, use EXT INPUT = ON).
Note that both EXT INPUT and OSC IN cannot be set to ON at the same time. If you are
unsuccessful in turning one on, check that the other is off.
If you set OSC IN = ON, press the NEXT PARAMETER key once and set OSC GAIN (see
below).
Osc Gain
When the OSC IN parameter is set to ON, an external signal applied to the EXT INPUT
connector will be scaled by a factor specified by the OSC GAIN parameter. Both parameters are
set from the [System Default] menu screen. The provided scaling factors are: 0.02, 0.2, and 2.
Parity
See Serial Parity.
Positive Feedback iR Compensation (PFIR)
Positive Feedback is one of two available iR Compensation techniques (see iR Compensation).
iR Compensation can be selected from the any of the three potentiostatic menu screens (IR
MODE). The default setting is OFF.
APPENDIX B — TECHNICAL REFERENCE
77
In the Positive Feedback technique, an analog positive feedback loop is established from the
output of the current measurement circuit to the Control Amplifier input. The user sets the loop
gain to approximately the value required to compensate for RU.
The principal advantage of Positive Feedback is that the correction is continuous. As a result,
correction remains effective even at the fastest scans possible with the Model 283. While this
technique is the only one possible for rapid scans (scans of 100 mV/s or faster), there are several
significant disadvantages.
1. Adjusting the feedback is a tedious and subjective process.
2. The feedback reduces the stability of the potentiostat and can lead to severe ringing or
oscillation.
3. Because of the effect on system stability, it is generally not possible to achieve 100%
compensation. Instead, the user normally has to be satisfied with a correction in the range of
75% to 90%.
4. The feedback assumes that the uncompensated resistance is constant. Should it vary, the
applied correction will be incorrect. RU is frequently not stable; it can change with the applied
potential, time, changes in cell geometry, and other factors.
Before the Positive Feedback Mode can be activated, it is necessary to set and enter the correct
value for RU, the value to be compensated. If the entered value is too low, RU will not be
adequately compensated. If it is too high, the system will be unstable and may even oscillate.
Once RU is entered, Positive Feedback iR Compensation can be activated. The resistance
resolution limit and maximum compensation as a function of Current Range is:
Current
Range
Maximum
Compensation
Resolution
Limit
1 nA
10 nA
100 nA
1 µA
10 µA
100 µA
1 mA
10 mA
100 mA
2 G
200 G
20 M
2 M
200 k
20 k
2 k
200 20 1 M
100 k
10 k
1 k
100 k
10 k
1
100 m
10 m
Resistance values have a resolution limited to 0.05% of the current-measuring resistor
associated with the Current Range. Thus, the accuracy of the value that is actually programmed
can vary with the Current Range. Moreover, as a result of this resolution limit, the value in effect
can change during the experiment if the Current Range changes either manually or
automatically. For this reason, care should be taken when using Positive Feedback iR
Compensation with auto-ranging.
Consider how the resolution limit affects the accuracy of the programmed value. For example,
assume a resistance of 1.234 k is entered on the 100 µA range. On that range, the resistance
resolution is 10 , giving an actual programmed resistance of 1230 . In other words, the
programmed resistance differs from that entered (front or rear panels) by 4 .
78
Model 283 User’s Manual
Let us continue with this example to see how error due to the resolution limit can occur when the
current range changes. If, during the experiment, the current range changes to 1 mA, where the
resistance resolution is 1 , the actual programmed resistance will change to 1234 . The
improved resolution allows the actual programmed value to be identically that originally entered.
Although this change could be a problem in some situations, it will usually be relatively minor.
The real problem occurs when shifting to a more sensitive range. For instance, if, in the example,
the current range were to shift to 10 µA, where the resolution limit is 100 , the actual
programmed resistance will become 1200 because the value can only be represented to the
nearest 100 . In other words, the error will now total 34 . Similarly, a further shift to 1 µA would
give a resistance of 1000 (234 error) and a shift to 100 nA would give a resistance of 0 (1234 error). Although this is a fairly large error, it is generally not significant because the
current is small.
Note: Should one later shift to less sensitive ranges, the error will be successively reduced with
each current range step.
Clearly, operators need to be mindful of the resolution limit for the "setup" current range and
should set a resistance appropriate to that limit. Also, if more sensitive ranges are used during
the experiment, users will have to be mindful of the impact the changing resolution will have on
the programmed resistance and of the possible consequences of large resistance errors.
Two procedures for establishing positive feedback compensation are provided. The first
procedure applies when the value of RU is known. The second applies when RU is not known.
If RU is known:
1. Set IR MODE = PFIR.
2. Press the NEXT PARAMETER key to display the PFIR COMP parameter. The current value
of assumed RU will be displayed.
3. Use the VALUE knob to set the value of RU to be compensated.
If RU is not known:
1. Set IR MODE = PFIR.
2. Press the NEXT PARAMETER key to display the PFIR COMP parameter. The current value
of assumed RU will be displayed.
3. Use the VALUE knob to set the value of RU to 0.00 ohms.
It is always advisable to start with zero iR compensation. With a higher starting value, there
is a definite risk factor in that the system may oscillate when the Positive Feedback Mode is
activated. High power, high amplitude oscillations can be destructive and definitely should be
avoided.
4. Program the Model 283 to apply a 62.5 Hz, ±50 mV square wave to the cell. (The ±50 mV
figure is not critical. Smaller or larger amplitudes if more appropriate to the chemistry, can be
used.) The following parameter values can be used.
Note: If LINE SYNC is set to ON, the frequency will be 15 Hz (60 Hz power) or 12.5 Hz
(50 Hz power). The procedure will generally be easier to perform with the LINE SYNC
set to OFF (less flicker on the oscilloscope display).
APPENDIX B — TECHNICAL REFERENCE
79
MODE =
POTENTIOSTATIC STEP
E INIT =
-0.05 V with respect to the potential of interest
T INIT =
PASS (see Note below)
E MID =
+0.05 V with respect to the potential of interest
T MID =
PASS (see Note below)
E FINAL = -0.05 V with respect to the potential of interest
CYCLES = CONTINUOUS
Note: 62.5 Hz rate results from setting both delays to PASS.
5. Set up the cell for the measurements to be made. (Any change at the cell will probably
change RU.)
6. Set the full-scale current range to the range that will be used in the measurement. If the
current range setting is changed, the actual value of iR compensation can change as
previously discussed.
7. Press the CELL ON key to establish the Cell ON state. Then press "Run" (F3) to apply the
square wave to the cell.
8. Monitor the I MONITOR connector with an oscilloscope. At the oscilloscope, use internal
triggering and display the waveform so As rise time can be readily observed. A horizontal
deflection factor of 2 ms per division will generally give good results.
9. Make sure the PFIR COMP parameter is shown on the LCD panel. Then, while observing
the displayed waveform on the oscilloscope, turn the VALUE knob slowly clockwise. The RU
compensation will increase, causing the decay intervals in the displayed waveform to
become shorter. You can see the actual value of R. compensation changing on the Model
283 display.
80
Model 283 User’s Manual
Fig. 30. I Output Waveforms as a Function of RU Compensation
(Square Wave Applied).
Fig. 30 illustrates the effect of the compensation. For optimum stability, the rise time should
be as fast as possible without ringing. When the uncompensated resistance is about 90% to
95% compensated, the waveform will show a smooth decay with perhaps just a bit of
undershoot. This is optimum for fast measurements.
As the compensation is increased to the 95% to 100% range, increasing ringing appears as
the system becomes more unstable. This level of compensation is not suitable for fast
measurements. Any data taken during the ring-down will be of doubtful validity. Also, even a
slight increase in compensation from this point (or a real decrease in the actual RU) could
cause the potentiostat to oscillate.
Compensation in the 95% to 100% range is best suited to slow experiments (such as for
corrosion). Since Current Interrupt Compensation is ideal for slow measurements, there will
normally be relatively few instances where Positive Feedback Compensation in the 95% to
100% range would be used.
When you are satisfied with the compensation level, turn off the cell and set up the other
parameters you need for the intended measurement. Unless changed, the compensation
level you set will remain in memory, ready to be applied whenever Positive Feedback iR
Compensation is activated.
Potential, Working Electrode
See Cell Potential.
Remote Operation
The Model 283 can be controlled from an IBM-compatible personal computer via either its
GPIB (IEEE-488) interface or its RS-232 interface. When it is under remote control, its LCD
panel displays the REMOTE screen and its front-panel controls, except for the Cell On key,
Cell Safety switch, and POWER switch, are inactive.
You can return it to local operation simply by pressing the LOCAL key (F5). But in remote
operation via GPIB, pressing F5 is effective only if the LOCAL LOCKOUT message has not
been sent from the host computer. This GPIB message would be sent only under special
circumstances, and in any case is not supported by PARI software. See Appendixes A and B
of the Model 283 Command Set Handbook for a discussion of GPIB communications
considerations.
Other ways of returning to local include applying the GO TO LOCAL message, deasserting
REN, or cycling the power. GO TO LOCAL is another GPIB message defined by IEEE-488
and explained in the Model 283 Command Set Handbook.
APPENDIX B — TECHNICAL REFERENCE
81
Reset
In the [System Interface] menu screen, F2 is assigned the "Reset' (Reset) function. This
function resets all experiment (not communications) parameters to their default values. When
you press F2, the message RESET SYSTEM? is displayed. If you want to reset the
experiment parameters, press the YES key (F4). All experiment parameter selections will be
cleared and default values restored. Note that this will not reset the parameters on the
[System Interface] menu (communications parameters and KNOB TIMEOUT).
This effect is not the same as that which occurs when the power is cycled. When the Model
283 powers down, all parameter values and selections are retained. When it is powered up,
these values are restored, except for Cell On, which becomes Cell Off.
If you wish to reset the parameters, including those on the [System Interface] menu, hold
down any front-panel key when you power up. Refer to Chapter 6, Section 6.8 for a more
detailed explanation of resetting methods.
Reverse Scan
In the Potentiostat Scan and Galvanostat Scan modes, the F5 key is assigned the "Reverse"
function. Pressing F5 during a scan reverses the direction of the scan.
Scan Rate
The scan rate is the rate of change of cell potential or current with respect to time. It is set
from the [Potentiostatic Scan] or [Galvanostatic Scan] menu screen.
Scan rates from 1 µV/s to 1 V/s can be specified in the [Potentiostatic Scan] mode. In the
[Galvanostatic Scan] mode, the range is 1 µX/s to X/s, where X is the selected current range.
Note that the Model 233 does not apply a linear scan, but rather a staircase scan. However,
as long as the individual steps are very small relative to the range scanned, linear scan
theory will apply to a close approximation. When LINE SYNC is not enabled, the nominal
step size is the Scan Rate/250, or 250 µV, whichever is larger. LINE SYNC causes larger
steps.
Note: Under remote control via the rear panel GPIB or RS-232 port, steps as small as
25 µV (MR = 1), or 2.5 µV (MR = 0), can be attained as explained in the Model 283
Command Set Handbook). For example, with a scan rate of 1 Vls, the step size will be
4 mV, because 1000/250 = 4.
Serial Baud Rate
A baud is a unit of signaling speed. In serial RS-232 communications, it refers to the number
of times the state or condition of a line changes per second. Baud rates from 110 to 19,200
can be selected from the [System Interface] menu screen. The default setting is 9,600 baud.
Serial Data Bits
Serial communications between the Model 283 and a host computer normally are in ASCII
code. You can also select a binary load or dump. From the [System Interface] menu screen,
you ran select a character length of either seven or eight data bits. Eight data bits are
required for binary loads and dumps. If "8" is selected, the Model 283 will always send a "0"
as the eighth (MSB) bit when transmitting ASCII codes.
Serial Echo
From the [System Interface] menu screen, you can select either SER. ECHO = OFF or SER.
ECHO = ON. If you select ON, each character received via the RS-232 port will be echoed
back to the character source. The Serial Echo is normally used only when the Model 283 is
connected to a CRT terminal.
Note: Do not confuse this function with the GPIB ECHO.
82
Model 283 User’s Manual
Serial Parity
In serial RS-232 communications, parity checking is an optional method of error detection. It
provides a direct way of detecting garbled data if the computer is programmed to only accept
words having the selected parity.
Parity checking traps errors in the serial data stream in the following manner. When the
Model 283 frames each character, it counts either the number of 0's or the number of 1's in
the data bits. It then appends a parity bit that corresponds to whether the count was even or
odd. The host computer also counts the 0's or l's in the data bits as they arrive, and
compares this count with the arriving parity bit. If an error is detected, a flag can be set and
retransmission can be requested.
From the [System Interface] menu screen, you can select either SERIAL PARITY = ODD,
SERIAL PARITY = EVEN, or SERIAL PARITY = NONE. The parity setting on the Model 283
must match that on the host. If ODD or EVEN parity is selected, the Model 283 will generate
the parity bit when transmitting and detect ft when receiving.
Serial Stop Bits
This sets the number of stop bits in RS-232 communications. The stop bit or bits signal the
end of a binary bit frame, and return the line to the idle state. Stop bits follow the parity bit;
either one or two may be used. Two stop bits give more reliable communications at high
baud rates.
Step Mode, Potentiostatic or Galvanostatic
The step mode [Potentiostatic Step] or [Galvanostatic Step] substitutes a sharp step between
two potential or current levels instead of a gradual scan. The cell potential or current will step
as quickly as possible between the two levels. The time between steps can be as long as 4
ms, during which time no other operation can be started.
The step feature is useful for applying pulse waveforms. For example, it allows the Model
283 to perform double-potential step chronoamperometry, in which the applied potential
starts at E INIT, remains there long enough to let the sample come to equilibrium with the
solution, steps to E MID for T MID (perhaps 2 seconds or so), and then steps to E FINAL,
which continues to be applied.
Stop Bits
See Serial Stop Bits.
T lnit T Mid, T Final
See Delays.
Terminator Character
See GPIB Terminator Character.
Test Echo
See GPIB Test Echo.
Update Q With Call Off
In a perfect instrument and cell system, the accumulated charge Q could not change when
the cell is disconnected, because no cell current would flow. But in a real system, no matter
how precise, some small charge may appear as a result of drift and other circuit variations.
Thus, setting UPDATE Q W/CELL OFF = NO (from the [System Default] menu) prevents
charge from accumulating when the cell is off. Choosing YES allows it to accumulate, and
might help to estimate drift errors.
APPENDIX B — TECHNICAL REFERENCE
83
84
Model 283 User’s Manual
$33(1',;&&RQQHFWRU3LQRXWV
C.1. Auxiliary Interface (Mating Connector DB9S)
This connector provides several functions only available when the Model
283 is being controlled from an external computer via the RS-232 or GPIB
(IEEE-488) port. Included are the signals required to drive a Model 303A
Static Mercury Drop Electrode. If this electrode is used, connections
between the Auxiliary Interface and the Model 303A are made via the
Model 507 Interface.
The Model 507 Interface is a universal power supply and control interface
for the Model 303A SMDE. It can relay DISPENSE, PURGE, and STIR signals from the Model 283
AUXILIARY INTERFACE connector to the Model 303A. The Model 507 is provided with all cables
required to make the necessary connections. Refer to the Model 507 Interface Installation Guide, Part
Number 222556, for installation instructions.
Pinouts for the AUXILIARY INTERFACE connector are listed below.
Pin
Signal
Function
1
ground
2
EXT TRIG
3
_________
DISPENSE
4
TRIG OUT
A TTL trigger output is provided on this line on application of the
TRIG command. The Trig Out baseline is either a logic 0 or a logic
1 (default is logic 0), according to the operand of the last applied
TRIG command. TRIG 0 establishes a logic 1 baseline. TRIG 1
establishes a logic 0 baseline. Once a logic 0 baseline is
established, subsequent TRIG 1's will cause a 10 to 20 ms wide
logic 1 pulse to be generated. Similarly, once a logic 1 baseline is
established, TRIG 0's will cause a 10 to 20 ms wide logic 0 pulse to
be generated.
5
BIT 0 IN
The level on this line will be read and reported to the host computer
if the command BIT 0 is applied.
6
+5V
+5 V at up to 100 mA is available for external use.
7
BIT 0 OUT
If Current Interrupt iR Compensation is not active, the level on this
line will be set to a logic 0 if the command BIT 0 0 is applied. It will
be set to a logic 1 if the command BIT 0 1 is applied.
This input allows an operation in progress to be halted via the WFT
command from an external computer. If the command WFT 0 is
applied, operation will resume when a TTL logic 0 is applied to the
EXT TRIG line. If the command WFT 1 is applied, operation will
resume when a TTL logic 1 is applied to the EXT TRIG line.
In applications where the Model 283 is being used with a Model
303A via a Model 507 Interface, this signal causes the Model 303A
to do a Dislodge/Dispense operation on command from an external
computer. The computer initiates the dispense operation by
applying a DISP command (see description in the Model 283
Command Set Handbook).
85
If Current Interrupt iR Compensation is active, this line will go high
about 3 µs before the start of the current interruption and will go low
about 7 µs after the end of the current interruption. This pulse can
be used to trigger an oscilloscope so that the iR Current Interrupt
waveform can be easily monitored at the E MONITOR connector.
8
_______
PURGE
9
STIR
When operating a Model 283 with a Model 303A SMDE via a
Model 507 Interface, this signal controls the Model 303A's purge
function in response to commands from the external computer. The
computer initiates a purge by applying a PURGE command (see
discussion of this command in the Model 283 Command Set
Handbook).
This signal controls the Model 303A's Stir function in response to
commands from an external computer. The assumption is that the
Model 303A is being used with a Model 305 Stirrer. It can also be
used to control the motor ON/OFF status of a Model 616 or 636
Rotating Electrode. In the Model 616 the motor-control jack is
called MOTOR STOP. In the Model 636 the motor-control jack is
called MOTOR CONTROL In both the 616 and the 636, an internal
jumper determines whether a TTL 0 or TTL 1 applied to the motorcontrol input will halt the motor.
C.2. Accessory Power Connector
Note that the pins on this DIN connector are not numbered
consecutively. They are numbered in the following sequence, looking
into the connector from the rear of the instrument and counting
clockwise from the keyway at the top.
Pin
1
4
2
5
3
86
Function
-28 V DC Regulated
-15 V DC Regulated
Power Ground
+15 V DC Regulated
+28 V DC Regulated
Model 283 User’s Manual
C.3. IEEE-488 GPIB Interface
Pin
1 ..
2 ..
3 ..
4 ..
5 ..
6 ..
7 ..
8 ..
9 ..
10 .
11 .
12 .
13 .
14 .
15 .
16 .
17 .
18 .
19 .
20 .
21 .
22 .
23 .
24 .
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Function
. . . . . . . . . DIO1
. . . . . . . . . DIO2
. . . . . . . . . DIO3
. . . . . . . . . DIO4
. . . . . . . . . . EOI
. . . . . . . . . DAV
. . . . . . . . NRFD
. . . . . . . . NDAC
. . . . . . . . . . IFC
. . . . . . . . . SRQ
. . . . . . . . . ATN
. . . . . . . SHIELD
. . . . . . . . . DIO5
. . . . . . . . . DIO6
. . . . . . . . . DIO7
. . . . . . . . . DIO8
. . . . . . . . . REN
. . . . . . . . GND 6
. . . . . . . . GND 7
. . . . . . . . GND 8
. . . . . . . . GND 9
. . . . . . . GND 10
. . . . . . . GND 11
LOGIC GROUND
C.4. RS-232C Interface
Pin
1
4
Function
Chassis Ground
Comment
Ties the chassis of the Model 283 to that of the computer.
2
Transmit Data
The Model 283 transmits on this line. It must connect to the
computer connector pin that receives serial data.
3
Receive Data
The Model 283 receives data on this line. It must connect to the
computer connector pin that transmits serial data.
Request to Send
This line is permanently asserted in the Model 283, that is, R is
always at a positive logic level (+ 12 V). As a result, the computer
continuously receives the message that the Model 283 is ready to
receive a character.
APPENDIX C — CONNECTOR PINOUTS
87
5
Clear to Send
6
Unused
7
Logic Ground
8-25
Unused
The computer controls the Model 283 via this line. To enable the
Model 283 to transmit, the line is placed at the positive logic level
(+3 V to +12 V). To hold off transmission by the Model 283, the line
must be at the negative logic level (-3 V to -12 V). Once this line
goes positive, data transfer, if initiated by an appropriate command,
will proceed rapidly. This line is pulled up to +12 volts so that, if it is
left unconnected, the Model 283 is allowed unimpeded
transmission.
Data signal levels should be with reference to logic ground. The
logic ground line of the Model 283 should inter-connect with the
logic ground line of the computer.
Note that the Model 283 RS-232 port is configured as a female DTE port (Data Terminal Equipment)
rather than as a DCE (Data Communications Equipment). Thus, cabling to most microcomputers can
be accomplished with a standard reversed or switched RS-232 cable, also known as a null modem
cable.
C.5. Expansion Interface
This connector is provided to allow for future expansion and
enhancements.
88
Model 283 User’s Manual
$33(1',;'0RGHO,PSHGDQFH
3ORWV
D.1. Introduction
This appendix contains a series of plots generated by the Model 398 AC Impedance application
software on a theoretical model having the same configuration and values as the Model 283 internal
ac dummy cell. To a close approximation, impedance plots performed on an actual dummy cell
should yield the same results.
D.2. Plots
Fig. 36. Imaginary Vs. Real Capacitance.
89
Fig. 37. Imaginary Vs. Real Admittance.
Fig. 38. Imaginary Vs. Real Admittance Zoomed.
90
Model 283 User’s Manual
Fig. 39. Nyquist Plot.
Fig. 40. Nyquist Plot Zoomed and Fitted.
91
Fig. 41. BODE Phase Plot.
Fig. 42. BODE Absolute Magnitude Plot.
92
Model 283 User’s Manual
Fig. 43. BODE Real Magnitude Plot.
Fig. 44. BODE Imaginary Magnitude Plot.
APPENDIX D — MODEL 398 IMPEDANCE PLOTS
93
94
Model 283 User’s Manual
,1'(;
175 Universal Programmer . . . . . .
270/250 Software . . . . . . . . . . . . .
303A . . . . . . . . . . . . . . . . . . . . .
352 . . . . . . . . . . . . . . . . . . . . . .
507 Interface . . . . . . . . . . . . . . . .
616 or 636 Rotating Electrode . . . .
A & B Connectors . . . . . . . . . . . .
A/D Input 1 . . . . . . . . . . . . . . . . .
A/D INPUT 2 . . . . . . . . . . . . . . . .
ac power . . . . . . . . . . . . . . . . . . .
Accessory Power . . . . . . . . . . . . .
Accessory Power Connector . . . . .
Address . . . . . . . . . . . . . . . . . . .
Air circulation . . . . . . . . . . . . . . .
Ambient Temperature Range . . . .
American polarity convention . . . .
Ancillary Functions . . . . . . . . . . . .
AUTO current range mode . . . . . .
AUTO switch indicator . . . . . . . . .
Automatic current ranging . . . . . . .
Auxiliary Inputs . . . . . . . . . . . . . .
Auxiliary interface . . . . . . . . . . . .
AUXSEL . . . . . . . . . . . . . . . . . . .
Back Panel . . . . . . . . . . . . . . . . .
BANDWIDTH . . . . . . . . . . . . . . .
Bandwidth (Stability versus Speed)
Battery replacement . . . . . . . . . . .
Baud Rate . . . . . . . . . . . . . . . . .
BNC Connectors . . . . . . . . . . . . .
Bottom Row Functions . . . . . . . . .
Calibrating the Model 283 . . . . . . .
Cell (Condition) at End . . . . . . . . .
CELL command . . . . . . . . . . . . .
Cell connectors . . . . . . . . . . . . . .
Cell Current . . . . . . . . . . . . . . . .
Cell Group . . . . . . . . . . . . . . . . .
CELL Indicator . . . . . . . . . . . . . .
CELL ON Key . . . . . . . . . . . . . . .
Cell Potential . . . . . . . . . . . . . . . .
Cell Safety . . . . . . . . . . . . . . . . .
CELL SAFETY switch . . . . . . . . .
CELL TYPE . . . . . . . . . . . . . . . .
[email protected] . . . . . . . . . . . . . . . .
character length . . . . . . . . . . . . . .
circuit description . . . . . . . . . . . . .
Galvanostat . . . . . . . . . . . . . .
signal conditioning . . . . . . . . . .
Ancillary Functions . . . . . . . . .
Potentiostatic operation . . . . . .
COMM ERROR message . . . . . . .
Command Set Handbook . . . . . . .
Communications Parameters . . . .
Computer Interfaces . . . . . . . . . . .
Connecting a Model 303A SMDE .
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25, 43, 74
......2
......2
......2
. . 29, 43
......2
. . . . . 30
. . . . . 10
. . . . . 27
......5
. . 29, 44
. . . . . 86
. . . . . 30
......7
. . . . . 63
. . . . . 31
. . . . . 59
. . . . . 24
. . . . . 24
. . . . . 24
. . . . . 59
. . 29, 85
17, 27, 59
. . . . . . 29
. . . 38, 65
. . . . . . 65
. . . . . . 61
. . . 65, 83
. . . . . . 25
. . . . . . 34
. . . . . . 39
. . . . . . 65
. . . . . . 20
. . . . . . 15
. . . . . . 52
. . . . . . 15
. . . . . . 20
. . . . . . 20
. . . . . . 66
. . . . 6, 11
.......6
. . . . . . 37
. . . 47, 52
. . . . . . 82
. . . . . . 55
. . . . . . 57
. . . . . . 59
. . . . . . 59
. . . . . . 55
. . . . . . 42
. . . . . 2, 3
. . . 35, 38
. . . . . . 63
. . . . . . 43
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.
Connecting a Pen Recorder . . . . .
Connecting an Oscilloscope . . . . .
Connector
D/A OUTPUT . . . . . . . . . . . . .
OUTPUT . . . . . . . . . . . . . . . .
Connector Diagrams
Accessory Power . . . . . . . . . .
Auxiliary Interface . . . . . . . . . .
Expansion Interface . . . . . . . .
IEEE-488 . . . . . . . . . . . . . . . .
Connector Pinouts . . . . . . . . . . . .
RS-232C . . . . . . . . . . . . . . . .
Connectors
A&B ..................
A/D INPUT 2 . . . . . . . . . . . . .
A/D INPUT I . . . . . . . . . . . . .
Accessory Power . . . . . . . . . .
Auxiliary Interface . . . . . . . . . .
BNC . . . . . . . . . . . . . . . . . . .
D/A OUTPUT . . . . . . . . . . . . .
Dummy Cell . . . . . . . . . . . . . .
E MONITOR . . . . . . . . . . . . .
Expansion Interface . . . . . . . .
EXT IN . . . . . . . . . . . . . . . . .
Gnd . . . . . . . . . . . . . . . . . . . .
I MONITOR . . . . . . . . . . . . . .
IEEE-488 Connector . . . . . . . .
MUX . . . . . . . . . . . . . . . . . . .
OUTPUT . . . . . . . . . . . . . . . .
PA Monitor . . . . . . . . . . . . . . .
RS-232 Connector . . . . . . . . .
CONTINUOUS . . . . . . . . . . . . . .
CONTINUOUS cycle . . . . . . . . . .
Controls and Indicators . . . . . . . . .
Convention
Polarity . . . . . . . . . . . . . . . . .
cooling . . . . . . . . . . . . . . . . . . . .
COUNTER connector . . . . . . . . . .
Counter Electrode cable . . . . . . . .
Current Auto-Ranging . . . . . . . . . .
Current Integral (Coulombs) Display
Current Interrupt iR Compensation .
Current Measurement . . . . . . . . .
Current Offset (I Offset) . . . . . . . .
Current Overload . . . . . . . . . . . . .
Current Range, Full Scale . . . . . . .
Current Range, Full Scale . . . . . .
Cycle Control . . . . . . . . . . . . . . .
Delays T lnit, T Mid, T Final . . . . .
Differential Electrometer . . . . . . . .
DIN connector . . . . . . . . . . . . . . .
Display/Control Group . . . . . . . . .
E & I Suppression . . . . . . . . . . . .
E Overload . . . . . . . . . . . . . . . . .
. . . . . . . . . . . 42
. . . . . . . . . . . 42
. . . . . . . . . . . 27
. . . . . . . . . . . 27
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29
29
30
30
85
87
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30
27
27
29
29
25
27
27
26
30
25
27
26
30
26
27
30
30
47
47
33
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31
.7
16
10
66
67
68
63
70
71
71
71
71
73
63
86
20
59
73
95
ERROR . . . . . . . . . . . . . . . . . . . .
Error Messages . . . . . . . . . . . . . . .
Expansion Interface . . . . . . . . . . . .
External Input . . . . . . . . . . . . . . . .
External Signal
Adding . . . . . . . . . . . . . . . . . . .
F1 (Coulombs or offset I) . . . . . . . .
F1 Through F5 Function keys . . . . .
F2 (Q-Reset) . . . . . . . . . . . . . . . . .
F3 (Start or Stop) . . . . . . . . . . . . . .
F4 (Hold or Resume) . . . . . . . . . . .
F5 (Reverse or Bypass) . . . . . . . . .
Filters . . . . . . . . . . . . . . . . . . . . . .
Frequency Response . . . . . . . . . . .
Fuse
Changing . . . . . . . . . . . . . . . . .
Galvanostat Operation . . . . . . . . . .
Galvanostatic Experiments . . . . . . .
Galvanostatic Modes . . . . . . . . . . .
GPIB ADDR . . . . . . . . . . . . . . . . .
GPIB Address . . . . . . . . . . . . . . . .
GPIB ECHO . . . . . . . . . . . . . . . . .
GPIB Terminator Character . . . . . .
GPIB Test Echo . . . . . . . . . . . . . .
I AUTO LIMIT . . . . . . . . . . . . . . . .
I/E FILTER . . . . . . . . . . . . . . . . . .
IEEE-488 GPIB Interface . . . . . . . .
Impedance Plots
Model 398 . . . . . . . . . . . . . . . .
Inspection . . . . . . . . . . . . . . . . . . .
Installation . . . . . . . . . . . . . . . . . .
Interface Group . . . . . . . . . . . . . . .
iR Compensation . . . . . . . . . . . . . .
KNOB TIMEOUT . . . . . . . . . . . . . .
LCD Display . . . . . . . . . . . . . . . . .
LCD Menu Screens . . . . . . . . . . . .
Line Fuses . . . . . . . . . . . . . . . . . .
LINE SYNC . . . . . . . . . . . . . . . . .
Line Voltage . . . . . . . . . . . . . . . . .
Line Voltage Selection . . . . . . . . . .
Line Voltage Setting . . . . . . . . . . . .
LISTEN . . . . . . . . . . . . . . . . . . . .
Maintenance . . . . . . . . . . . . . . . . .
Mode key . . . . . . . . . . . . . . . . . . .
Model 303A SMDE . . . . . . . . . . . .
Model 616 or 636 . . . . . . . . . . . . . .
Operating Modes . . . . . . . . . . . . . .
Galvanostatic . . . . . . . . . . . . . .
Potentiostatic . . . . . . . . . . . . . .
OSC GAIN . . . . . . . . . . . . . . . . . .
Osc In . . . . . . . . . . . . . . . . . . . . .
Output DACs . . . . . . . . . . . . . . . . .
OVERLOAD Indicators . . . . . . . . . .
Parameter keys . . . . . . . . . . . . . . .
Positive Feedback iR Compensation
Potential/Current Control . . . . . . . .
Potentiostat Operation . . . . . . . . . .
Potentiostatic Experiments . . . . . . .
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40, 49
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43
48
23
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48
49
74
63
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57
51
51
36
74
36
75
75
38
37
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. . 89
...9
...9
. . 23
63, 76
36, 77
. . . 22
. . . 33
....9
37, 77
....5
....6
....5
. . . 23
. . . 61
. . . 21
. . . 43
. . . 43
....2
. 2, 32
. 2, 32
37, 77
. . . 77
. . . 59
. . . 20
. . . 23
. . . 77
. . . 63
. . . 55
. . . 45
Potentiostatic Modes . . . .
Power Cord . . . . . . . . . . .
Power Cord Plug . . . . . . .
Power Requirements . . . .
Power-Up . . . . . . . . . . . .
Reference Electrode cable
Remote Computer Control
Remote Operation . . . . . .
Reset . . . . . . . . . . . . . . .
Resetting Parameters . . . .
Reverse Scan . . . . . . . . .
RS-232C Interface . . . . . .
Running Your Experiment .
Scan Rate . . . . . . . . . . . .
Sense cable . . . . . . . . . .
Sense connector . . . . . . .
SERIAL BAUD . . . . . . . .
Serial Baud Rate . . . . . . .
SERIAL BITS . . . . . . . . .
Serial Data Bits . . . . . . . .
SERIAL ECHO . . . . . . . .
Serial Parity . . . . . . . . . .
SERIAL PRTY . . . . . . . .
SERIAL STOP . . . . . . . .
Serial Stop Bits . . . . . . . .
Service . . . . . . . . . . . . . .
Setting Cell Current . . . . .
Signal Conditioning . . . . .
Specifications . . . . . . . . .
Step Mode
Galvanostatic . . . . . . .
Potentiostatic . . . . . . .
System key . . . . . . . . . . .
TALK . . . . . . . . . . . . . . .
TERMINATOR . . . . . . . .
UPDATE Q W/CELL OFF
Value knob . . . . . . . . . . .
Ventilation . . . . . . . . . . . .
Working Electrode cable . .
key . . . . . . . . . . . . . .
key . . . . . . . . . . . . . .
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...5
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. . 10
...1
. . 81
. . 82
. . 38
. . 82
. . 87
. . 48
. . 82
. . 10
. . 19
. . 36
. . 82
. . 36
. . 82
36, 82
. . . 83
. . . 36
. . . 36
. . . 83
. . . 61
. . . 52
. . . 59
. . . 63
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83
83
21
23
36
38
23
.7
10
24
24
Model 283 User’s Manual
97
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