operating instruction manual for the model gm

operating instruction manual for the model gm
OPERATING INSTRUCTION MANUAL
FOR THE
MODEL GM-700
HALL EFFECT GAUSSMETER
WARNING!
DO NOT ATTEMPT TO OPERATE THIS EQUIPMENT BEFORE YOU HAVE
THOROUGHLY READ THIS INSTRUCTION MANUAL.
TABLE OF CONTENTS
1.0 Introduction .......................................................................................................................... 1
2.0 Factory Calibrations, Installed Options and Certification ....................................................... 2
3.0 Setup ................................................................................................................................... 3
3.1 Input Line Voltage and Fuse .................................................................................... 3
3.2 Connecting Sensors................................................................................................. 3
3.3 Hall Effect Sensor Calibration .................................................................................. 5
4.0 Operation and Menu Options................................................................................................ 6
4.1 Mode (Absolute, Relative)........................................................................................ 7
4.2 Zero......................................................................................................................... 7
4.3 Alarm....................................................................................................................... 7
4.4 Limits (Control Output)............................................................................................. 7
4.5 Units (Gauss, Tesla) ................................................................................................ 8
4.6 Ports (RS-232, IEEE-488.2) ..................................................................................... 8
4.7 Calibrate (Sensor Sensitivity)................................................................................... 8
4.8 Analog Output Limits ............................................................................................... 8
5.0 Interfacing ............................................................................................................................ 9
5.1 RS-232 Computer Interface ..................................................................................... 9
5.2 IEEE-488.2 Computer Interface (Optional)............................................................. 10
5.3 Analog Output........................................................................................................ 10
5.4 Audible Alarm ........................................................................................................ 10
5.5 Control Output ....................................................................................................... 10
6.0 Theory of Operation ........................................................................................................... 12
6.1 Hall Effect Magnetic Field Sensing ........................................................................ 12
6.2 GM-700 Circuit Description .................................................................................... 12
7.0 Limited Warranty Policy ..................................................................................................... 13
Appendix A. - Computer Interface Command Reference .......................................................... 14
Appendix B. - Factory Calibration............................................................................................. 25
B.1 Factory Calibration of Hall Effect Sensor ............................................................... 25
B.2 Factory Calibration of the Analog Output Option.................................................... 26
Appendix C. - Line Voltage Controller Module - Option 5.......................................................... 28
1.0
Introduction
The GM-700 Hall Effect Gauss Meter is a state of the art instrument that provides excellent
accuracy and resolution. Its versatile architecture allows configuration to virtually any Hall Effect
sensor.
The GM-700 has user-adjustable high and low setpoints that may be used to control other
equipment the user requires. Also included is an audible alarm that is controlled with separate
user-adjustable high and low setpoints. If the magnetic field is between the high and low setpoints
the alarm is silent. If below the low setpoint or above the high setpoint the alarm sounds until
silenced by the operator.
Computer control via RS-232 is available in the standard configuration. Remote control via the
latest IEEE-488.2 command set is available as an option. LabVIEW® virtual instrument drivers are
available to allow computer control via a familiar, intuitive interface. A wide variety of other options
are also available that allow the instrument to be upgraded and tailored to your particular
requirements.
1
2.0
Factory Calibrations, Installed Options and Certification
GM-700 Serial Number:
Internal Reference:
Input Voltage:
Firmware Version:
100 VAC:
115 VAC:
230 VAC:
Sensor:
HSU-2
HSP-T
Type:
HSU-1
Calibration:
Sensor Manufacturer / Serial No:
HSP-A
Other:
Sensor Sensitivity:
mV/kg
Excitation Current:
Control Output: TTL:
Analog Output (Option 1):
Type:
Open Collector: ______
Not Installed:
0-1 Volt:
4-20mA:
Computer Interface Installed: RS-232:
X
IEEE-488.2 (Option 2):
Notes:
Certified:
Date:
2
Other:
3.0
Setup
The GM-700 is delivered to you fully tested and ready to operate. This includes sensor calibration
if Cryomagnetics supplied the sensor with the instrument. Calibration will also be complete if the
sensitivity of an existing installed sensor was specified at the time of order.
3.1
Line Voltage and Fuse
Unless otherwise specified, the GM-700 is configured for operation using 100 to 115 VAC +/- 10%,
50/60 Hz input power. The serial number tag on the rear panel of the unit indicates the factory
voltage setting.
The line voltage setting can be changed to 230 VAC if desired. Always disconnect the power cord
from the unit prior to opening the case. To open the GM-700, remove the two screws from the rear
panel of the unit. Also remove the screws on the RS-232 and Sensor(s)/IO connectors. The rear
panel can then be pulled back and the cover of the GM-700 can be slid off. Figure 3.0 indicates
the changes in circuit board jumpers inside the unit used to make a change in line voltage.
Figure 3.0 - Line Voltage Jumper Settings
Transformer Primary Jumpers
Line Voltage
100V, 115V
200V, 230V
JP1
Short
Open
JP2
Open
Short
JP3
Short
Open
JP4
Open
Short
The fuse for the GM-700 is mounted on the main circuit board inside the unit. Should the fuse
need to be changed, open the GM-700 as described above. Locate the fuse - it is a cylindrical
device labeled F1 and can be found on the right side of the unit near the main transformer.
Replace the fuse only with another fuse of the same type. Use only Wickmann part number
19374-035-K (250V, 0.25A, time lag). Never replace the fuse with a wire.
3.2
Connecting Sensors
Sensors connect to the GM-700 through the rear panel DB-15F connector labeled “Sensor(s)/IO”.
This connector provides service not only to the sensor, but also to the control output signal
generated by the GM-700 and the 4-20mA analog output signal, (optional). Figure 3.1 indicates
the pin designations for the Sensor(s)/IO connector.
3
********** IMPORTANT ***********
1) Connections should NEVER be made directly to the connector on the rear panel. Always
solder to a mating connector that is not attached to the unit.
Connections should be
double-checked for accuracy prior to attaching to the GM-700 and powering the unit ON.
2) NEVER connect/disconnect the sensors with the GM-700 powered ON.
************************************************
Figure 3.1 - Sensor Connector Wiring - DB-15F
View Facing Rear Panel Connector
Function
Pin #
1
Sensor I+
9
N/C
2
Sensor I-
10
N/C
3
Sensor V+
11
N/C
4
Sensor V-
12
N/C
5
Analog Output (Optional) 4-20 mA I-
13
N/C
6
Analog Output (Optional) 4-20 mA I+
14
Control Output
7
N/C
15
GND
8
N/C
Pin #
Function
Cryomagnetics, Inc. Hall Effect sensors have four (4) lead wires. Lead function and wire colors are
specified on the data sheet accompanying the sensor.
Cabling between the Hall Effect sensor and the GM-700 should be of appropriate size such that a
high voltage drop across the I+ and I- leads does not occur. Voltage drop across I+ to I- at the GM700 should not exceed 2.0 volts with the sensor connected.
4
3.3
Hall Effect Sensor Calibration
Calibration of Hall Effect sensors is performed through the front panel keypad of the GM-700.
Calibration can not be performed through the GM-700 computer interfaces.
To calibrate a sensor, power ON the GM-700 (the sensor does not need to be connected). Press
the MENU key and use the UP or DOWN arrow keys to select CAL from the opening menu. When
CAL is highlighted, the GM-700 will show the present calibration setting (sensitivity) for the sensor
on the second display line. Press ENTER to access the calibration values.
The GM-700 indicates “Ch 1 Sensitivity:” on the first line of the display, and the present setting for
the sensitivity on the second line. The sensitivity may be set to any value between 10 microvolts
per kilogauss and 500 millivolts per kilogauss. The sensitivity may be computed using the sensor
calibration information supplied with the sensor and physical location and orientation of the sensor
relative to the central field to be measured. Alternatively, if the sensor is placed in a known field
and the measurement value observed, the sensitivity may be scaled by multiplying the sensitivity
by the known field and dividing the result by the observed measurement. If this method is used,
The instrument should be fully warmed up (about 1 hour of operation) and the probe ZERO
function should be used with the Hall sensor in a zero field before starting the calibration (see
Section 4.2). Press ENTER to accept and save the displayed value, or MENU to exit without
saving the value.
5
4.0
Operation and Menus
Setup of the GM-700 can be performed either through the front panel keypad and simple menu
instructions or through remote computer interface (RS-232 or IEEE-488.2). Calibration is only
supported through the front panel keypad. In the following sections there are detailed descriptions
of how to recalibrate for different sensors, set the audible alarm, and configure the controller
functions.
Before connecting the Hall Effect sensor or other cabling to the GM-700, connect the power cord
provided with your GM-700 to an appropriate power source.
Power the instrument ON and
familiarize yourself with the display. The GM-700 has a normal operational display that will show
"Magnetic Field" on the upper line and the measured value on the lower line when in Absolute
mode.
Magnetic Field
-25.9877 T
If the control output is active it is indicated by a diamond on the lower display line. If an alarm
condition is present is indicated by an "A" on the lower display line.
Magnetic Field
-259.877 kG ♦A
The GM-700 may be switched to relative mode to display a reference field on the lower display
line, and the difference between the measured field and reference field on the upper display line.
35.G ∆
-100.000 kG Ref
To change the mode or relative reference levels, probe zero, alarm points, control output limits,
display units, computer communication parameters, calibration, or any other user-settable options,
you must press the MENU key. The menu function will be displayed on the first line and present
setting on the second line. Pressing the DOWN key will select the next menu item to the right.
Pressing UP will select the next menu item to the left. The display will scroll left or right and
display three menu items in each scroll position.
>Mode< Zero Alarm
Absolute
6
Pressing MENU again returns the instrument to normal display and operations. Be aware that
some computer interface commands are not available while the menu system is active (see
Appendix A).
There are numerous user-adjustable options available. The following outline indicates options and
the menu headings under which they are found.
4.1
Mode
Under the Mode menu item, the user can select either Absolute or Relative operational mode. This
item appears first in the menu list since it may be changed frequently to observe either the actual
field or changes to a previously established reference field. If Relative is selected, the value of a
reference field may be set by selecting Adjust and using the UP, DOWN, and ENTER keys, or the
present field may be measured by selecting Measure and pressing ENTER when the measured
field is the at the desired reference value.
4.2
Zero
The GM-700 allows the probe to be 'zeroed' when no field is applied to establish zero field which
eliminates offsets due to probe temperature, instrument temperature, or drift in electronic
components. When Zero is selected from the menu a 'Zero Probe?' prompt is displayed. 'Yes'
must be selected to initiate the function. Note that if the probe is zeroed when at a non-zero field
there will be no way to display a true absolute field, although relative mode could be used to
effectively compensate for the offset due to an erroneous zero.
4.3
Alarm
The GM-700 has an internal audible alarm which can be set to activate when the measured field
falls outside of user setpoints. The set points for the high and low alarm limits are set in the
“Alarm” menu. The alarm function gives a front panel display indication when it is activated - “A”
appears on the right side of the active display line to indicate an alarm condition. The audible
alarm can be silenced by pressing any front panel key on the GM-700; however, the visual
indication of the alarm condition, “A” on the display, is maintained until the measured field is
between the alarm set points.
4.4
Limits
The GM-700 has a control output which will activate when the measured field falls outside of user
setpoints. The set points for the high and low control output limits are set in the “Limits” menu.
The control output function gives a front panel display indication when it is activated - a diamond
pattern appears on the right side of the active display line when the control output is activated. The
7
control output will remain active until the measured field is between the set points.
4.5
Units
The Units menu item allows the user to set the display units of the GM-700. Available options are
Gauss and Tesla. Once the system of units is selected, the GM-700 autoranges between Gauss
and kilogauss or Tesla and millitesla.
4.6
Ports
The Ports menu item enables the user to select the computer interface which is active (RS-232 or
IEEE-488.2 - if installed), and to set up the parameters of the computer interface such as baud
rate, address, etc. When the Ports menu item is highlighted, the current settings of the computer
interfaces are displayed on the second line. To change any of the Port options, press ENTER
when “Ports” is highlighted. Then select the option that is to be changed:
RS-232
Baud rate may be set to 9600, 4800, 2400, or 1200. Factory default is 9600.
GPIB
Device address may be selected from 0 - 31. Factory default is 0.
In accordance with the IEEE-488.2-1992 specification, changes are not made immediately but are
applied the next time the unit is powered up.
4.7
Calibrate
Under the Calibrate (Cal) menu item, the user can set effective sensitivity of the Hall Effect sensor.
When “Cal” is highlighted, the present sensor sensitivity setting is shown on the second line of the
display. The units used by the GM-700 (kilogauss or Tesla) for calibration is set with the Units
menu item. Pressing ENTER while “Cal” is highlighted allows the user to adjust the sensitivity
value. Refer to section 3.3 for the Hall Effect sensor calibration procedures.
4.8
Analog Output Limits (Option 1)
The analog output limits (AnlgOut) menu item enables the user to set the lower and upper limits for
the analog output. If the measured field is less than the lower limit, the minimum analog output
value will be set on the analog output port. If the measured field is above the upper limit, the
maximum analog output value will be set on the analog output port. If the measured field is
between the lower and upper limits, a linear interpolation will be used to set the value on the analog
output port.
8
5.0 Interfacing
The GM-700 comes standard with an RS-232 computer interface. Front panel functions, except
calibration functions, may be accessed using the corresponding command string over the RS-232
port. In addition, an IEEE-488.2 port is available as an option. This port conforms to the IEEE488.2-1992 standard.
5.1 RS-232 Computer Interface
An RS-232 computer interface port is provided as standard equipment on all GM-700s. The port is
accessed through the DB-9F connector on the rear panel of the instrument. The interface is factory
configured for 9600 baud, 8 data bits, 1 stop bit, no parity. Figure 5.0 indicates the proper pin
designations for the port. Figure 5.1 details available RS-232 port commands.
Figure 5.0 - RS-232 Port Connector Wiring
Pin #
GM-700 Pin Function
1, 4, 6, 7, 8, 9
N/C
2
RS-232 Transmit
3
RS-232 Receive
5
Ground
View Facing Rear Panel Connector
Commands available to the GM-700 operator over the RS-232 computer interface are given in
Appendix A. The commands available through RS-232 are identical to those available through
IEEE-488.2; however, some commands may be IEEE-488.2 specific and may not provide
responses consistent with the RS-232 interface.
Command strings are normally limited to 30 characters when the RS-232 interface is used. A
<RETURN> will be generated internally when any line longer than the maximum is encountered,
and any valid commands in the received line prior to the internally generated <RETURN> will be
processed.
An output buffer of 32 characters is used although longer responses can be
successfully generated. All remote commands are case insensitive, allowing upper or lower case
to be used without affecting operation of the commands.
When the RS-232 interface is selected all commands sent to the instrument will be echoed
including the terminating ASCII <RETURN> character, followed by a <NEWLINE> character when
command processing is complete.
9
5.2
IEEE-488.2 Computer Interface
The GM-700 may have an optional IEEE-488.2 computer interface (Option 2).
The GM-700
implements SH1, AH1, T6, L4, SR1, RL0, PP0, DC1, DT0, C0, and E1 options. The commands
are compliant with the IEEE-488.2 standard.
Reference:
IEEE Standard Codes, Formats, Protocols, and Common Commands (IEEE Std
488.2-1992) provides a detailed description of the IEEE common commands (identifiable in the
command list by the asterisk as the first character.)
The command list and structure is identical to the RS-232 command set. Reference Appendix A
for a detailed description.
5.3
Analog Output
An analog output from the GM-700 is available as an option (Option 1). This output can be
specified at the time of purchase to be either 4-20mA or 0-1V. If the 4-20 mA option is installed,
the signal is found on the GM-700 rear panel DB-15F connector, pins 5 and 6 (see Figure 3.1). If
the 0-1V analog output option is installed, the signal is found on the GM-700 rear panel BNC
connector. In either case, the analog output signal is linear and proportional to the sensor reading
as described in section 4.8.
5.4
Audible Alarm
A user-adjustable audible alarm is standard on the GM-700. The alarm may be set through the
front panel menu system (see sections 4.3). The alarm gives the user an audible indication if the
measured magnetic field falls outside the alarm set points. Once the alarm is activated, it may be
silenced by any front panel keystroke. It will only be reactivated after a normal reading (i.e., one
between the alarm setpoints) is detected by the GM-700, followed by another reading in which an
alarm condition again exists. The audible alarm may be disabled by setting limits beyond the
range of field measurements.
5.5
Control Output
The GM-700 in its standard configuration is capable of generating a control signal to be used with
remote equipment.
10
The control output may be set to be either “open collector” or “0-5V”. Refer to Section 2.0 of this
manual for the factory settings of your particular GM-700. Figure 3.1 indicates the output pins
designated to carry the Control Output signals, and Figure 5.1 indicates the jumper setting to
change the configuration.
Figure 5.1 - Control Output Format Setting (Jumper 22)
TTL Compatible
Open Collector
Short
Open
If the output will consequently be driving a solenoid valve or relay, the output will typically be
configured as open collector. If the control output is simply being monitored by other equipment
(e.g., a computer), the output should be configured as TTL Compatible (0-5V).
When the GM-700 is used in conjunction with Option 5, the Line Voltage Controller Module, the
unit is capable of driving solenoid valves requiring 115V/230V AC. Option 5 provides the user with
a fused and opto-isolated line voltage output. Refer to Appendix C for a technical description of
Option 5.
11
6.0
Theory of Operation
The GM-700 is configured for a specific sensor excitation current at the factory to optimize
accuracy and to minimize noise. Although the excitation current may be changed in the factory
calibration menu, component changes may be needed to maintain low noise performance,
accuracy, and sensor protection. Consult the factory if this is necessary.
6.1
Hall Effect Magnetic Field Sensing
The Hall Effect sensor is a solid state device with four terminals. The GM-700 provides constant
current DC excitation through the I+ and I- terminals, and measures the Hall voltage generated by
the sensor across the V+ and V- terminals. The Hall Effect sensor generates an output voltage
proportional to the excitation current, the magnetic flux density, and the sine of the angle between
the magnetic field vector B and the plane of the Hall generator.
6.2
GM-700 Circuit Description
The GM-700 is a 68HC11 microprocessor based instrument. This microprocessor has built-in
EEPROM that is used to hold factory calibration and configuration data, as well as user entered
calibration and setup information. Consequently, it is not possible to simply change the processor
with another 68HC11. The unit will not work properly with a new processor until it has been
initialized by the factory.
The processor controls virtually all aspects of the GM-700 including the display, keypad, a
precision constant current source, a low noise precision preamplifier, and the high stability, 24-bit
analog-to-digital converter used to monitor sensor voltages. Due to the flexibility and stability of
the GM-700’s circuits, very high resolution, accuracy, and low noise performance is achieved.
The GM-700’s display is a bright, vacuum fluorescent unit having high contrast. It is capable of full
alphanumerics and can clearly be read from a significant distance.
12
7.0
Limited Warranty Policy
Cryomagnetics, Inc. warrants its products to be free from defects in materials and workmanship.
This warranty shall be effective for one (1) year after the date of shipment from Cryomagnetics.
Cryomagnetics reserves the right to elect to repair, replace, or give credit for the purchase price of
any product subject to warranty adjustment. Return of all products for warranty adjustment shall be
FOB Oak Ridge, TN, and must have prior authorization for such return from an authorized
Cryomagnetics, Inc. representative.
This warranty shall not apply to any product which has been determined by Cryomagnetics, Inc.
inspection to have become defective due to abuse, mishandling, accident, alteration, improper
installation or other causes. Cryomagnetics, Inc. products are designed for use by knowledgeable,
competent technical personnel.
In any event, the liability of Cryomagnetics, Inc. is strictly limited to the purchase price of the
equipment supplied by Cryomagnetics, Inc. Cryomagnetics, Inc. shall not assume liability for any
consequential damages associated with use or misuse of its equipment.
13
Appendix A
Computer Interface Command Reference
Commands available over the computer interface are separated into commands that are IEEE
488.2 specific, commands that are inhibited when the operator menu is accessed, and commands
that are always available. All command mnemonics that elicit a response from the instrument end
with a question (?) character. The general command format is as follows:
<subcommand1>;<subcommand2>;<subcommand3><RETURN>
where a subcommand is formatted
<Command Mnemonic><SPACE><Parameter>
Example:
*IDN?; UNITS T;UNITS?<RETURN>
Responses to each subcommand are separated by semicolons. The above example would return:
Cryomagnetics,GM-700,2002,2.09;T<RETURN><LINEFEED>
where the serial number is 2002 and the firmware version number is 2.09.
Error Handling and Command Availability
The ERROR command allows error messages to be enabled or disabled when the RS-232
interface is used. The IEEE-488.2 status mechanisms may always be used to determine if an error
occurred processing a command, and the category of the error. Some commands are unavailable
if the instrument menu is being accessed by an operator at the instrument. If a command available
only in operate mode is received while the menus are being accessed, a device dependent error is
reported in the Extended Status Register(ESR), and the message "Blocked by menu" will be
returned if error reporting is enabled when using the RS-232 interface.
The following table lists the GM-700 commands, shows the GM-700 mode where the command
may be used and provides a short command description. Command details are provided in the
reference that follows.
14
Command
Available
Description
ERROR
Operate
Set error response mode for RS-232 interface
ERROR?
Always
Query error response mode
HIGH
Operate
Set high threshold for control output activation
HIGH?
Operate
Query high threshold for control output activation
H-ALM
Operate
Set audible alarm high threshold
H-ALM?
Operate
Query audible alarm high threshold
LOW
Operate
Set low threshold for control output activation
LOW?
Operate
Query low threshold for control output activation
L-ALM
Operate
Set audible alarm low threshold
L-ALM?
Operate
Query audible alarm low threshold
MEAS
Operate
Start measurement
MEAS?
Operate
Query last completed measurement
MODE
Operate
Set absolute or relative display mode
MODE?
Operate
Query selected mode
REF
Operate
Set reference field for relative mode
REF?
Operate
Query reference field
UNITS
Operate
Select units
UNITS?
Operate
Query selected units
ZERO
Operate
Zero probe
*CLS
Always
Clear Status Command
*ESE
Always
Standard Event Status Enable Command
*ESE?
Always
Standard Event Status Enable Query
*ESR?
Always
Standard Event Status Register Query
*IDN?
Always
Identification Query
*OPC
Always
Operation Complete Command
*OPC?
Always
Operation Complete Query
*RST
Always
Reset Command
*SRE
Always
Service Request Enable Command
*SRE?
Always
Service Request Enable Query
*STB?
Always
Read Status Byte Query
*TST?
Always
Self-Test Query
*WAI
Operate
Wait-to-Continue Command
15
Command Reference
This section describes how each GM-700 command is used and provides a cross reference to
related commands. The command syntax sections show required elements enclosed in <angle
brackets> and optional parameters enclosed in [square brackets]. All numbers are decimal (base
10).
ERROR
Set error response mode for RS-232 interface
Availability:
Operate Mode
Command Syntax:
ERROR <Error Mode>
Example:
ERROR 1
Parameter Range:
0 or 1
(0 - disable error reporting, 1 - enable error reporting)
Description: The ERROR command enables or disables error messages when the RS-232
interface is used. It is much easier to handle errors under program control when using the RS-232
interface if error messages are disabled, but it is desirable to enable error messages if a terminal
program is used to interactively control and query the GM-700.
Related Commands: ERROR?
ERROR?
Query error response mode
Availability:
Always
Command Syntax:
ERROR?
Response:
<Error Mode>
Response Example:
0
Response Range: 0 or 1
Description: The ERROR? query returns the selected error reporting mode.
Related Commands:
ERROR
HIGH
Set high threshold for control output activation
Availability:
Operate Mode
Command Syntax:
HIGH [Field Strength]
Example:
HIGH 65.0
Default Parameter:
0.0
Parameter Range: Calibration Range
Description: The HIGH command sets the high threshold for the control output activation in the
present units. If the field strength exceeds the threshold the control output will be activated.
Related Commands:
HIGH?, H-ALM, H-ALM?, LOW, LOW?, L-ALM, L-ALM?
HIGH?
Query high threshold for control output activation
Availability:
Operate Mode
16
Command Syntax:
HIGH?
Response:
<High Field Strength > <Units>
Response Example:
65.0000 kG
Response Range: Calibration Range
Description: The HIGH? query returns the high threshold for control output activation in the
present units.
Related Commands:
HIGH, H-ALM, H-ALM?, LOW, LOW?, L-ALM, L-ALM?
H-ALM
Set audible alarm high threshold
Availability:
Operate Mode
Command Syntax:
H-ALM [Alarm Field Strength]
Example:
H-ALM 65.0
Default Parameter:
0.0
Parameter Range: Calibration Range
Description: The H-ALM command sets the high threshold for the audible alarm in the present
units. If the measured field exceeds the threshold the audible alarm will sound.
Related Commands: H-ALM?, L-ALM, L-ALM?, UNITS, UNITS?
H-ALM?
Query audible alarm high threshold
Availability:
Operate Mode
Command Syntax:
H-ALM?
Response:
<Alarm Field Strength > <Units>
Response Example:
3.20000 T
Response Range: Calibration Range
Description: The H-ALM? query returns the audible alarm high threshold in the present. If the
measured field exceeds the threshold the audible alarm will sound.
Related Commands:
H-ALM, L-ALM, L-ALM?, UNITS, UNITS?
LOW
Set low threshold for control output activation
Availability:
Operate Mode
Command Syntax:
LOW [Field Strength]
Example:
LOW 45.0
Default Parameter:
0.0
Parameter Range: Calibration Range
Description: The LOW command sets the low threshold for the control output activation in the
present units. If the field strength falls below the threshold the control output will be activated.
Related Commands:
HIGH, HIGH?, H-ALM, H-ALM?, LOW?, L-ALM, L-ALM?
LOW?
Query low threshold for control output activation
Availability:
Operate Mode
17
Command Syntax:
LOW?
Response:
<Low Field Strength> <Units>
Response Example:
45.0000 kG
Response Range: Calibration Range
Description: The LOW? query returns the low threshold for control output activation in the
present units.
Related Commands:
HIGH, HIGH?, H-ALM, H-ALM?, LOW, L-ALM, L-ALM?
L-ALM
Set audible alarm low threshold
Availability:
Operate Mode
Command Syntax:
L-ALM [Field Strength]
Example:
L-ALM 65.0
Default Parameter:
0.0
Parameter Range: Calibration Range
Description: The L-ALM command sets the low threshold for the audible alarm in the present
units. If the field strength falls below the threshold the audible alarm will sound.
Related Commands: H-ALM, H-ALM?, L-ALM?, UNITS, UNITS?
L-ALM?
Query audible alarm low threshold
Availability:
Operate Mode
Command Syntax:
L-ALM?
Response:
<Low Alarm Field Strength> <Units>
Response Example:
65.0000 kG
Response Range: Calibration Range
Description: The L-ALM? query returns the audible alarm low threshold in the present units. If
the field strength falls below the threshold the audible alarm will sound.
Related Commands:
H-ALM, H-ALM?, L-ALM, UNITS, UNITS?
MEAS
Start measurement
Availability:
Operate Mode
Command Syntax:
MEAS
Description: The MEAS command starts a measurement. The DATA READY bit will be set in the
status byte returned by the *STB? command when the measurement is complete.
Related Commands:
MEAS?, *STB?
MEAS?
Query last completed measurement
Availability:
Operate Mode
Command Syntax:
MEAS?
Response:
<Field Strength> <Units>
18
Response Example:
15.0000 kG
Description: The MEAS? query returns latest reading in the present units. If a reading is in
progress the previous reading is returned.
Related Commands:
MEAS, *STB?
MODE
Set absolute or relative display mode
Availability:
Operate Mode
Command Syntax:
MODE <Display Mode>
Example:
MODE R
Parameter Range:
Relative or Absolute
Description: The MODE command sets the display mode for field measurement. Mode may be
set to absolute or relative. When absolute is selected the measured field strength is displayed.
When relative is selected the GM-700 display shows a Delta symbol is displayed by the units, the
difference between the measured field and the reference field is displayed on the lower display
line, and the reference field is displayed on the upper display line. Measurements returned on the
computer interface will be relative to the reference field when relative mode is selected.
Related Commands: MODE?, REF, REF?
MODE?
Query display mode
Availability:
Operate Mode
Command Syntax:
MODE?
Response:
<Display Mode>
Response Example:
Relative
Response Range: Relative or Absolute
Description: The MODE? command returns the display mode that is presently selected.
Related Commands: MODE, REF, REF?
REF
Set reference field for relative mode
Availability:
Operate Mode
Command Syntax:
REF <Field Strength>
Example:
REF -0.015
Parameter Range:
Calibration Range
Description: The REF command sets the reference field to be used when relative mode is
selected. If units are set to Tesla or millitesla the parameter must be given in Tesla. If units are
set to kilogauss or Gauss the parameter must be given in kilogauss.
Related Commands: MODE, MODE?, REF?, UNITS, UNITS?
19
REF?
Query reference field
Availability:
Operate Mode
Command Syntax:
REF?
Response Example:
-0.01500 kG
Response Range: Calibration Range
Description: The REF? query returns the value set by the last REF command in the present
units.
Related Commands: MODE, MODE?, REF
UNITS
Select units
Availability:
Operate Mode
Command Syntax:
UNITS <Unit Selection>
Example:
UNITS T
Parameter Range:
T, mT, G, or kG
Description: The UNITS command sets the units to be used for all input and display operations.
Units may be set to Tesla or Gauss. Note that the instrument display will indicate Tesla or
millitesla if set to Tesla, and Gauss or kilogauss if set to Gauss dependent on the measured
values. The computer interface supports only Tesla or kilogauss.
Related Commands:
HIGH, HIGH?, H-ALM, H-ALM?, LOW, LOW?, L-ALM, L-ALM?, MEAS,
MEAS?, UNITS?
UNITS?
Query selected units
Availability:
Operate Mode
Command Syntax:
UNITS?
Response:
<Selected Units>
Response Example:
T
Response Range: Tesla or Gauss
Description: The UNITS? command returns the units used for all input and display operations.
Note that the instrument display will indicate Tesla or millitesla if set to Tesla, and Gauss or
kilogauss if set to Gauss dependent on the measured values. The computer interface supports only
Tesla or kilogauss.
Related Commands: HIGH, HIGH?, H-ALM, H-ALM?, LOW, LOW?, L-ALM, L-ALM?, MEAS,
MEAS?, UNITS
ZERO
Zero Probe
Availability:
Operate Mode
Command Syntax:
ZERO
Description: The ZERO command takes measurements at all instrument gains and computes
20
new offsets that are applied to future readings. It is recommended that the command only be used
when the instrument is fully warmed up with the probe in a near zero field. This command requires
about 16 seconds to complete, and the unit will not respond to any commands except IEEE-488
serial polls until the command completes.
Related Commands:
None
*CLS
Clear Status Command
Availability:
Always
Command Syntax:
*CLS
Description: The *CLS command operates per IEEE Std 488.2-1992 by clearing the Standard
Event Status Register (ESR) and resetting the MAV bit in the Status Byte Register (STB).
Related Commands:
None
*ESE
Standard Event Status Enable Command
Availability:
Always
Command Syntax:
*ESE <mask>
Example:
*ESE 255
Default Parameter:
0
Parameter Range: 0 to 255
Description: The *ESE command operates per IEEE Std 488.2-1992 by setting the specified
mask into the Standard Event Status Enable Register (ESE).
Related Commands:
*ESE?
*ESE?
Standard Event Status Enable Query
Availability:
Always
Command Syntax:
*ESE?
Response:
<ESE Mask>
Response Example:
255
Response Range: 0 to 255
Description: The *ESE? command operates per IEEE Std 488.2-1992 by returning the mask set
in the Standard Event Status Enable Register (ESE) by a prior *ESE command.
Related Commands:
*ESE
*ESR?
Standard Event Status Register Query
Availability:
Always
Command Syntax:
*ESR?
Response:
<Standard Event Status Register>
Response Example:
128
Response Range: 0 to 255
21
Description: The *ESR? command operates per IEEE Std 488.2-1992 by returning the contents
of the Standard Event Status Register and then clearing the register.
Status Byte Bit Allocations:
X
X
X
X
X
X
0
1
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Related Commands:
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*IDN?
Identification Query
Availability:
Always
Command Syntax:
*IDN?
Response:
<Manufacturer>,<Model>,<Serial #>,<Firmware Level>
Response Example:
Cryomagnetics,GM-700,2002,2.09
Serial # Range:
2000 to 9999
Operation Complete
Request Control
Query Error
Device Dependent Error
Execution Error
Command Error
User Request
Power On
*ESE, *ESE?
Firmware Level Range: 1.00 to 9.99
Description: The *IDN? command operates per IEEE Std 488.2-1992 by returning the GM-700
manufacturer, model, serial number and firmware level.
Related Commands:
None
*OPC
Operation Complete Command
Availability:
Always
Command Syntax:
*OPC
Description: The *OPC command operates per IEEE Std 488.2-1992 by placing the Operation
Complete message in the Standard Event Status Register (ESR). The GM-700 processes each
command as it is received and does not defer any commands for later processing.
Related Commands:
*OPC?
*OPC?
Operation Complete Query
Availability:
Always
Command Syntax:
*OPC?
Description: The *OPC command operates per IEEE Std 488.2-1992 by placing an ASCII
character "1" in the output queue since the GM-700 does not defer any commands for later
processing.
Related Commands:
*OPC
22
*RST
Reset Command
Availability:
Always
Command Syntax:
*RST
Description: The *RST command operates per IEEE Std 488.2-1992 by returning the GM-700 to
its power up configuration. This initializes the instrument to its lowest gain configuration.
Related Commands:
None
*SRE
Service Request Enable Command
Availability:
Always
Command Syntax:
*SRE <mask>
Example:
*SRE 255
Default Parameter:
0
Parameter Range: 0 to 255
Description: The *SRE command operates per IEEE Std 488.2-1992 by setting the specified
mask into the Service Request Enable Register (SRE).
Related Commands:
*SRE?
*SRE?
Service Request Enable Query
Availability:
Always
Command Syntax:
*SRE?
Response:
<SRE Mask>
Response Example:
255
Response Range: 0 to 255
Description: The *SRE? command operates per IEEE Std 488.2-1992 by returning the mask set
in the Service Request Enable Register (SRE) by a prior *SRE command.
Related Commands:
*SRE
*STB?
Read Status Byte Query
Availability:
Always
Command Syntax:
*STB?
Response:
<Status Byte>
Response Example:
65
Response Range: 0 to 255
Description: The *STB? command operates per IEEE Std 488.2-1992 by returning the Status
Byte.
Status Byte Bit Allocations:
X
X
X
X
X
X
X
X
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Data Ready
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* TST?
Self-Test Query
Availability:
Always
Command Syntax:
*TST?
Response:
<Self test status>
Response Example:
1
Alarm Active
Control Output Active
Unused
MAV (Message Available)
ESB (Extended Status Byte)
MSS (Master Summary Status)
Menu Selected
Response Range: 1
Description: The *TST? command operates per IEEE Std 488.2-1992 by returning the self test
status. Explicit tests are not performed in response to this command, but a 1 is returned for
compliance with the specification.
Related Commands:
None
* WAI
Wait-to-Continue Command
Availability:
Always
Command Syntax:
*WAI
Description: The *WAI? command operates per IEEE Std 488.2-1992 by accepting the command
without generating an error. Since the GM-700 only implements sequential commands the nooperation-pending flag is always TRUE.
Related Commands:
OPC, *OPC?
24
Appendix B
Factory Calibration
The GM-700 Factory Calibration is used to establish sensor excitation levels and hardware
calibration.
If these procedures are not carefully performed the instrument may not function
properly. Factory assistance is recommended.
********** WARNING **********
Load resistors and/or Sensors must be attached to perform the calibration.
Power MUST be removed while making ALL connections.
************************************
The factory calibration menu is invoked by holding the MENU and ENTER keys while power is
applied to the unit. The display will show
Instrument Cal
>Abort< Ch1 Ch2
or,
Instrument Cal
>Abort< Ch1 Ch2 Anlg
if the analog output option is installed. If the analog output is installed, it must be recalibrated after
the Ch1 factory calibration is performed. Use the UP and DOWN keys to select the calibration to
be performed, and press ENTER to begin the calibration.
B.1
Factory Calibration of a Hall Effect Sensor Input
Factory calibration of a Hall Effect sensor input requires a 3 to 5 ohm resistor to be placed between
I- and I+, and a jumper connected between I- and V-. Stable isolated references of about 1.2 volts
and 32 millivolts with source impedances of less than 100 ohms must be available to perform this
procedure. Once all connections have been made, enter the factory calibration menu as described
in the preceeding paragraph.
Select Ch 1 using the UP or DOWN arrow keys and press ENTER. The value of the GM-700’s
internal current sense resistor will be displayed. The value should not need to be changed unless
R30 has been changed to support a different sensor type. Press ENTER to accept the value of the
25
current sense resistor.
The value of the sense current will be displayed next. Use the UP or DOWN arrow keys to make
this display the desired excitation current and press ENTER to accept the value.
The GM-700 now will display:
Short ADC Inputs
<Enter> when ready
Connect V+ directly to V-, and press ENTER to begin calibration. This step requires about a
minute for completion.
The GM-700 now will display:
Attach 1.2 Volt Ref
<Enter> when ready
Connect the 1.2V reference between V+ and V-, and press ENTER. The GM-700 will now allow
the value of the voltage to be adjusted using the UP and DOWN buttons. Press ENTER when the
correct value is displayed to calibrate at the high reference voltage. This step requires about thirty
seconds.
The GM-700 now will display:
Attach 32mV Ref
<Enter> when ready
Connect the 32 mV reference between V+ and V-, and press ENTER to complete the calibration.
This step requires about a minute.
B.2
Factory Calibration of the Analog Output Option
The GM-700’s Analog Output must be recalibrated whenever the Ch 1 factory calibration is
changed. In preparation for calibrating the analog output, the sensor must be connected to the
GM-700. If the Analog Output is configured for 0-1 Volt Output, no load is required at the analog
output. If the Analog Output is configured as 4-20mA Output, either a load resistor of less than 600
ohms or the actual current loop itself must be attached to pins 5 and 6 of the rear panel DB15
connector (current must be able to flow in order for the calibration to be made). The value of the
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resistor is not important.
Select ANLG on the Factory Calibration Menu and press ENTER. The Analog Output calibration is
automatic and will be completed in about 3 seconds.
27
Appendix C
Line Voltage Controller Module – Option 5
Overview
The Line Voltage Controller Module enables the GM-700 to control a 115 VAC load up to 1 Amp
using the GM-700 Low and High setpoints.
Connections
An interconnection cable is provided with the Line Voltage Controller Module to connect the GM700 to the Line Voltage Controller Module and to the sensor. The DB-15M connector attaches to
the GM-700, the DB-9F attaches to the Line Voltage Controller Output Module. The sensor
connector on the cable is labeled. Output connections are standard 110V output sockets.
DB-9M Pinout
Pin 1 - Control input (0V - enabled, open - disabled)
Pin 6 - +15V input (10 ma max)
Pin 9 - Ground
Fuses
The output is fused on the rear panel of the module with a user replaceable 2 amp 250VAC fuse.
Slow blow fuses should not be used.
Theory of Operation
The 'hot' side of the output is switched using an opto-isolated solid state switch rated for 20-500Hz
operation. These switches exhibit a 1 mA off-state leakage current which will be observed as 90100 VAC if the output is checked with a voltmeter with no load attached to the output.
28
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