Installing the USB-2537

Installing the USB-2537

USB-2537

User's Guide

Document Revision 5, August, 2007

© Copyright 2007, Measurement Computing Corporation

Your new Measurement Computing product comes with a fantastic extra —

Management committed to your satisfaction!

Refer to www.mccdaq.com/execteam.html

for the names, titles, and contact information of each key executive at Measurement

Computing.

Thank you for choosing a Measurement Computing product—and congratulations! You own the finest, and you can now enjoy the protection of the most comprehensive warranties and unmatched phone tech support. It’s the embodiment of our mission:

ƒ To provide PC-based data acquisition hardware and software that will save time and save money.

Simple installations minimize the time between setting up your system and actually making measurements. We offer quick and simple access to outstanding live FREE technical support to help integrate MCC products into a DAQ system.

Lifetime warranty: Every hardware product manufactured by Measurement Computing Corporation is warranted against defects in materials or workmanship for the life of the product. Products found defective are repaired or replaced promptly.

Lifetime Harsh Environment Warranty®: We will replace any product manufactured by Measurement Computing

Corporation that is damaged (even due to misuse) for only 50% of the current list price. I/O boards face some tough operating conditions, some more severe than the boards are designed to withstand. When a board becomes damaged, just return the unit with an order for its replacement at only 50% of the current list price. We don’t need to profit from your misfortune. By the way, we honor this warranty for any manufacturer’s board that we have a replacement for.

30 Day Money Back Guarantee: You may return any Measurement Computing Corporation product within 30 days of purchase for a full refund of the price paid for the product being returned. If you are not satisfied, or chose the wrong product by mistake, you do not have to keep it. Please call for an RMA number first. No credits or returns accepted without a copy of the original invoice. Some software products are subject to a repackaging fee.

These warranties are in lieu of all other warranties, expressed or implied, including any implied warranty of merchantability or fitness for a particular application. The remedies provided herein are the buyer’s sole and exclusive remedies. Neither

Measurement Computing Corporation, nor its employees shall be liable for any direct or indirect, special, incidental or consequential damage arising from the use of its products, even if Measurement Computing Corporation has been notified in advance of the possibility of such damages.

HM USB-2537.doc

3

Trademark and Copyright Information

TracerDAQ, Universal Library, Harsh Environment Warranty, Measurement Computing Corporation, and the Measurement

Computing logo are either trademarks or registered trademarks of Measurement Computing Corporation.

Windows, Microsoft, and Visual Studio are either trademarks or registered trademarks of Microsoft Corporation

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Information furnished by Measurement Computing Corporation is believed to be accurate and reliable. However, no responsibility is assumed by Measurement Computing Corporation neither for its use; nor for any infringements of patents or other rights of third parties, which may result from its use. No license is granted by implication or otherwise under any patent or copyrights of Measurement Computing Corporation.

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Notice

Measurement Computing Corporation does not authorize any Measurement Computing Corporation product for use in life support systems and/or devices without prior written consent from Measurement Computing Corporation.

Life support devices/systems are devices or systems which, a) are intended for surgical implantation into the body, or b) support or sustain life and whose failure to perform can be reasonably expected to result in injury.

Measurement Computing Corporation products are not designed with the components required, and are not subject to the testing required to ensure a level of reliability suitable for the treatment and diagnosis of people.

4

Table of Contents

Preface

About this User's Guide .......................................................................................................................7

What you will learn from this user's guide .........................................................................................................7

Conventions used in this user's guide .................................................................................................................7

Where to find more information .........................................................................................................................7

Chapter 1

Introducing the USB-2537 ....................................................................................................................8

Overview: USB-2537 features............................................................................................................................8

Software features ................................................................................................................................................8

Chapter 2

Installing the USB-2537 ........................................................................................................................9

What comes with your USB-2537 shipment?.....................................................................................................9

Hardware .......................................................................................................................................................................... 9

Optional components ........................................................................................................................................................ 9

Signal conditioning accessories .......................................................................................................................................10

Additional documentation................................................................................................................................................10

Unpacking the USB-2537.................................................................................................................................10

Installing the software ......................................................................................................................................10

Installing the USB-2537 ...................................................................................................................................11

Configuring the hardware.................................................................................................................................11

Connecting the board for I/O operations ..........................................................................................................12

Connectors, cables – main I/O connector.........................................................................................................................12

68-pin SCSI connector differential and single-ended pin outs (P5) .................................................................................13

TB-100 terminal board connector to SCSI connector pin out ..........................................................................................15

40-pin header connector pin outs .....................................................................................................................................16

Four-channel TC terminal pin out (TB7) .........................................................................................................................19

Cabling .............................................................................................................................................................20

Field wiring and signal termination .................................................................................................................................21

Using multiple USB-2537s per PC...................................................................................................................21

Chapter 3

Functional Details ...............................................................................................................................22

USB-2537 components.....................................................................................................................................22

USB-2537 block diagram .................................................................................................................................24

Synchronous I/O – mixing analog, digital, and counter scanning ....................................................................25

Analog input .....................................................................................................................................................25

Analog input scanning .....................................................................................................................................................25

Thermocouple input..........................................................................................................................................28

Tips for making accurate temperature measurements ......................................................................................................28

Analog output ...................................................................................................................................................29

Digital I/O.........................................................................................................................................................30

Digital input scanning ......................................................................................................................................................30

Digital outputs and pattern generation .............................................................................................................................31

Triggering .........................................................................................................................................................31

Hardware analog triggering .............................................................................................................................................31

Digital triggering..............................................................................................................................................................31

Software-based triggering................................................................................................................................................32

Stop trigger modes ...........................................................................................................................................................32

Pre-triggering and post-triggering modes ........................................................................................................................32

Counter inputs ..................................................................................................................................................33

5

USB-2537 User's Guide

Mapped channels .............................................................................................................................................................33

Counter modes .................................................................................................................................................................34

Debounce modes..............................................................................................................................................................35

Encoder mode ..................................................................................................................................................................38

Timer outputs....................................................................................................................................................42

Example: Timer outputs...................................................................................................................................................42

Using detection setpoints for output control.....................................................................................................42

What are detection setpoints? ..........................................................................................................................................42

Setpoint configuration overview......................................................................................................................................43

Setpoint configuration......................................................................................................................................................44

Using the setpoint status register......................................................................................................................................45

Examples of control outputs ............................................................................................................................................45

Detection setpoint details.................................................................................................................................................49

FIRSTPORTC, DAC, or timer update latency.................................................................................................................50

Chapter 4

Calibrating the USB-2537 ...................................................................................................................51

Chapter 5

Specifications......................................................................................................................................52

Analog input .....................................................................................................................................................52

Accuracy..........................................................................................................................................................................52

Thermocouples ................................................................................................................................................................53

Analog outputs..................................................................................................................................................53

Digital input/output...........................................................................................................................................54

Counters............................................................................................................................................................54

Input sequencer.................................................................................................................................................55

Trigger sources and modes ...............................................................................................................................56

Frequency/pulse generators ..............................................................................................................................56

Power consumption ..........................................................................................................................................56

External power..................................................................................................................................................57

USB specifications ...........................................................................................................................................57

Environmental ..................................................................................................................................................57

Mechanical .......................................................................................................................................................57

Signal I/O connectors and pin out ....................................................................................................................57

68-pin SCSI connector pin outs .......................................................................................................................................58

40-pin header connector pin outs .....................................................................................................................................59

TC connector pin out (TB7).............................................................................................................................................63

6

Preface

About this User's Guide

What you will learn from this user's guide

This user's guide explains how to install, configure, and use the USB-2537 so that you get the most out of its analog I/O, thermocouple (TC) input, digital I/O, and counter/timer I/O features.

This user's guide also refers you to related documents available on our web site, and to technical support resources.

Conventions used in this user's guide

For more information on …

Text presented in a box signifies additional information and helpful hints related to the subject matter you are reading.

Caution! Shaded caution statements present information to help you avoid injuring yourself and others, damaging your hardware, or losing your data.

<

#:#>

bold text

italic text

Angle brackets that enclose numbers separated by a colon signify a range of numbers, such as those assigned to registers, bit settings, etc.

Bold text is used for the names of objects on the screen, such as buttons, text boxes, and check boxes. For example:

1. Insert the disk or CD and click the OK button.

Italic text is used for the names of manuals and help topic titles, and to emphasize a word or phrase. For example:

The InstaCal installation procedure is explained in the Quick Start Guide.

Never touch the exposed pins or circuit connections on the board.

Where to find more information

The following electronic documents provide information that can help you get the most out of your USB-2537.

ƒ MCC's Specifications: USB-2537 (the PDF version of the Specifications chapter in this guide) is available on our web site at www.mccdaq.com/pdfs/USB-2537.pdf

.

ƒ MCC's Quick Start Guide is available on our web site at www.mccdaq.com/PDFmanuals/DAQ-Software-Quick-Start.pdf

.

ƒ MCC's Guide to Signal Connections is available on our web site at www.mccdaq.com/signals/signals.pdf

.

ƒ MCC's Universal Library User's Guide is available on our web site at www.mccdaq.com/PDFmanuals/sm-ul-user-guide.pdf

.

ƒ MCC's Universal Library Function Reference is available on our web site at www.mccdaq.com/PDFmanuals/sm-ul-functions.pdf

.

ƒ MCC's Universal Library for LabVIEW

User’s Guide is available on our web site at www.mccdaq.com/PDFmanuals/SM-UL-LabVIEW.pdf

.

USB-2537 User's Guide (this document) is also available on our web site at www.mccdaq.com/PDFmanuals/USB-2537.pdf

.

7

Chapter 1

Introducing the USB-2537

Overview: USB-2537 features

The USB-2537 is supported under popular Microsoft

®

Windows

®

operating systems. The USB-2537 board is a multifunction measurement and control board designed for the USB bus.

The USB-2537 provides either 32 differential or 64 single-ended analog inputs with 16-bit resolution from its

40-pin connectors. It offers seven software-selectable analog input ranges of ±10 V, ±5 V, ±2 V, ±1 V, ±0.5 V,

±0.2 V, and ±0.1V.

You can configure up to four of the analog inputs as differential thermocouple (TC) inputs.

The USB-2537 also has four 16-bit, 1 MHz analog output channels with an output range of -10 V to +10 V.

The board has 24 high-speed lines of digital I/O, two timer outputs, and four 32-bit counters. It provides up to

4 MHz scanning on all digital input lines

1

.

You can operate all analog I/O, digital I/O, and counter/timer I/O synchronously.

Software features

For information on the features of InstaCal and the other software included with your USB-2537, refer to the

Quick Start Guide that shipped with your device. The Quick Start Guide is also available in PDF at www.mccdaq.com/PDFmanuals/DAQ-Software-Quick-Start.pdf

.

Check www.mccdaq.com/download.htm

for the latest software version.

1

Higher rates—up to 12 MHz—are possible depending on the platform and the amount of data being transferred.

8

Installing the USB-2537

What comes with your USB-2537 shipment?

As you unpack your USB-2537, verify that the following components are included.

Hardware

ƒ

USB-2537 (with seven standoffs)

Chapter 2

ƒ USB cable (2-meter length)

Optional components

Cables and signal conditioning accessories that are compatible with the USB-2537 are not included with USB-

2537 orders, and must be ordered separately.

If you ordered any of the following products with your board, they should be included with your shipment.

9

USB-2537 User's Guide

PS-9V1AEPS-2500 power supply

Installing the USB-2537

Cables

CA-68-3R CA-68-3S (3-feet)

CA-68-6S (6-feet)

C40FF-x

Signal conditioning accessories

MCC provides signal termination products for use with the USB-2537. Refer to the "

Field wiring and signal termination " section for a complete list of compatible accessory products.

Additional documentation

In addition to this hardware user's guide, you should also receive the Quick Start Guide (available in PDF at www.mccdaq.com/PDFmanuals/DAQ-Software-Quick-Start.pdf).

This booklet supplies a brief description of the software you received with your USB-2537 and information regarding installation of that software. Please read this booklet completely before installing any software or hardware.

Unpacking the USB-2537

As with any electronic device, you should take care while handling to avoid damage from static electricity. Before removing the USB-2537 from its packaging, ground yourself using a wrist strap or by simply touching the computer chassis or other grounded object to eliminate any stored static charge.

If any components are missing or damaged, notify Measurement Computing Corporation immediately by phone, fax, or e-mail:

ƒ Phone: 508-946-5100 and follow the instructions for reaching Tech Support.

ƒ Fax: 508-946-9500 to the attention of Tech Support

ƒ Email: [email protected]

Installing the software

Refer to the Quick Start Guide for instructions on installing the software on the Measurement Computing Data

Acquisition Software CD. This booklet is available in PDF at www.mccdaq.com/PDFmanuals/DAQ-Software-

Quick-Start.pdf

.

We recommend that you download the latest Windows Update onto your computer before installing and operating the USB-2537.

10

USB-2537 User's Guide Installing the USB-2537

Installing the USB-2537

To connect the USB-2537 to your system, turn your computer on, and connect the USB cable to a USB port on your computer or to an external USB hub that is connected to your computer. The USB cable provides power and communication to the USB-2537.

When you connect the USB-2537 for the first time, a

Found New Hardware

popup balloon (Windows XP) or dialog (other Windows versions) opens as the USB-2537 is detected.

When this balloon or dialog closes, the installation is complete.

The

power LED

(bottom LED) blinks during device detection and initialization, and then remains solid as long as the USB-2537 has sufficient power. If the power provided from the USB is not sufficient, the LED turns off, indicating you need a PS-9V1AEPS-2500 power supply.

When the board is first powered on, there is usually a momentary delay before the power LED begins to blink, or come on solid.

Connect external power, if used, before connecting the USB cable to the computer

If you are using a PS-9V1AEPS-2500 power supply, connect the external power cable to the USB-2537 before connecting the USB cable to the computer. This allows the USB-2537 to inform the host computer (when the

USB cable is connected) that the board requires minimal power from the computer’s USB port.

In general, all standoffs should be used to mount the board to a metal frame.

The standoff at this location connects to the USB chassis for shunting electrostatic discharge.

The standoff at this location connects to the USB-

2537’s internal chassis plane for shunting electrostatic discharge.

Caution! Do not disconnect any device from the USB bus while the computer is communicating with the

USB-2537, or you may lose data and/or your ability to communicate with the USB-2537.

Configuring the hardware

All hardware configuration options on the USB-2537 are software-controlled. You can select some of the configuration options using InstaCal, such as the analog input configuration (64 single-ended or 32 differential channels), and the edge used for pacing when using an external clock. Once selected, any program that uses the

Universal Library initializes the hardware according to these selections.

You need a PS-9V1AEPS-2500 power supply (sold separately) when there is insufficient power from the USB port. However, you can use this power supply in any scenario.

11

USB-2537 User's Guide Installing the USB-2537

Caution! Avoid redundant connections. Ensure there is no signal conflict between SCSI pins and the associated header pin (J5 - J8). Also make sure there is no conflict between theTB7 TC connections and the SCSI and/or the 40-pin header connections.

Failure to do so could possibly cause equipment damage and/or personal injury.

Also, turn off power to all devices connected to the system before making connections. Electrical shock or damage to equipment can result even under low-voltage conditions.

Information on signal connections

General information regarding signal connection and configuration is available in the Guide to Signal

Connections. This document is available on our web site at www.mccdaq.com/signals/signals.pdf

.

Caution! Always handle components carefully, and never touch connector pins or circuit components unless you are following ESD guidelines in an appropriate ESD-controlled area. These guidelines include using properly-grounded mats and wrist straps, ESD bags and cartons, and related procedures.

Avoid touching board surfaces and onboard components. Only handle boards by their edges. Make sure the USB-2537 does not come into contact with foreign elements such as oils, water, and industrial particulate.

The discharge of static electricity can damage some electronic components. Semiconductor devices are especially susceptible to ESD damage.

Connecting the board for I/O operations

Connectors, cables – main I/O connector

The following table lists the board connectors, applicable cables, and compatible accessory products for the

USB-2537.

Board connectors, cables, and compatible hardware

Parameter Specification

Connector type

Compatible cables — main connector

Compatible cables — 40-pin connectors

Compatible accessory products using the

CA-68-3R, CA-68-3S, or CA-68-6S cables

Compatible accessory products using the C40FF-x cable

Main connector: 68-pin standard "SCSI type III" female connector

Auxiliary connectors: Four, 40-pin header connectors

CA-68-3R — 68-pin ribbon cable; 3 feet.

CA-68-3S — 68-pin shielded round cable; 3 feet.

CA-68-6S — 68-pin shielded round cable; 6 feet

C40FF-x

TB-100 terminal connector

CIO-MINI40

12

USB-2537 User's Guide Installing the USB-2537

68-pin SCSI connector differential and single-ended pin outs (P5)

The 68-pin SCSI connector—labeled P5 on the board—provides 16 single-ended analog channels or eight

differential analog channels. Refer to the "40-pin header connector pin outs" section starting on page 16 to learn

the pin outs for accessing up to 64 single-ended/32 differential analog channels using the P5 and P6 connectors.

Caution! Avoid redundant connections. Make sure there is no signal conflict among the SCSI pins, the 40pin header connector pins (J5 - J8), and the TB7 TC connections. Failure to do so could possibly cause equipment damage and/or personal injury.

68-pin SCSI connector pin out (labeled P5 on the board)

16-channel single-ended mode

ACH0 68 • • 34 ACH8

AGND 67 • • 33 ACH1

ACH9 66

ACH2 65

AGND 64

• •

• •

32 AGND

31 ACH10

• • 30 ACH3

ACH11 63 • • 29 AGND

SGND 62 • • 28 ACH4

ACH12 61 • • 27 AGND

ACH5 60 • • 26 ACH13

AGND 59 • • 25 ACH6

ACH14 58 • • 24 AGND

ACH7 57

• •

23 ACH15

XDAC3 56

• •

22 XDAC0

XDAC2 55 • • 21 XDAC1

NEGREF (reserved for self-calibration) 54 • • 20 POSREF (reserved for self-calibration)

GND 53

A1 52

A3 51

• •

• •

19 +5 V

18 A0

• • 17 A2

A5 50 • • 16 A4

A7 49 • • 15 A6

B1 48 • • 14 B0

B3 47

B5 46

• • 13 B2

• • 12 B4

B7 45

C1 44

• •

• •

11 B6

10 C0

C3 43

• •

C5 42

• •

9 C2

8 C4

C7 41 • •

GND 40 • •

CNT1 39 • •

CNT3 38 • •

TMR1 37 • •

GND 36 • •

GND 35 • •

7 C6

6 TTL TRG

5 CNT0

4 CNT2

3 TMR0

2 XAPCR

1 XDPCR

13

USB-2537 User's Guide Installing the USB-2537

68-pin SCSI connector pin out (labeled P5 on the board)

8-channel differential mode

ACH0 HI 68

• •

34 ACH0 LO

AGND 67

• •

33 ACH1 HI

ACH1 LO 66 • • 32 AGND

ACH2 HI 65 • • 31 ACH2 LO

AGND 64 • • 30 ACH3 HI

ACH3 LO 63 • • 29 AGND

SGND 62 • • 28 ACH4 HI

ACH4 LO 61 • • 27 AGND

ACH5 HI 60 • • 26 ACH5 LO

AGND 59 • • 25 ACH6 HI

ACH6 LO 58 • • 24 AGND

ACH7 HI 57 • • 23 ACH7 LO

XDAC3 56

XDAC2 55

• •

• •

22 XDAC0

21 XDAC1

NEGREF (reserved for self-calibration) 54

• •

20 POSREF (reserved for self-calibration)

GND 53

• •

19 +5 V

A1 52 • • 18 A0

A3 51 • • 17 A2

A5 50 • • 16 A4

A7 49 • • 15 A6

B1 48 • • 14 B0

B3 47 • • 13 B2

B5 46 • • 12 B4

B7 45 • • 11 B6

C1 44 • • 10 C0

9 C2 C3 43 • •

C5 42

• •

C7 41

• •

GND 40

• •

8 C4

7 C6

6 TTL TRG

CNT1 39 • •

CNT3 38 • •

TMR1 37 • •

GND 36 • •

GND 35 • •

5 CNT0

4 CNT2

3 TMR0

2 XAPCR

1 XDPCR

14

USB-2537 User's Guide Installing the USB-2537

TB-100 terminal board connector to SCSI connector pin out

SCSI connector pin out assignments for TB-7 terminal board connector

(differential analog signals in parentheses)

TB2 screw terminals SCSI pin TB1 screw terminal

+5V 19

GND

*

A0 18

A1 52

A2 17

A3 51

A4 16

A5 50

A6 15

A7 49

B0 14

B1 48

B2 13

B3 47

B4 12

B5 46

B6 11

B7 45

C0 10

C1 44

C2 9

C3 43

C4 8

C5 42

C6 7

C7 41

TTLTRG 6

GND

*

CNT0 5

CNT1 39

CNT2 4

CNT3 38

TMR0 3

TMR1 37

XDPCR 1

GND

*

SCSI pin

ACH0 (ACH0 HI)

ACH8 (ACH0 LO)

AGND

ACH1 (ACH1 HI)

ACH9 (ACH1 LO)

AGND

ACH2 (ACH2 HI)

ACH10 (ACH2 LO)

AGND

ACH3 (ACH3 HI)

ACH11 (ACH3 LO)

AGND

68

34

**

33

66

**

65

31

**

30

63

**

ACH4 (ACH4 HI)

ACH12 (ACH4 LO)

AGND

ACH5 (ACH5 HI)

ACH13 (ACH5 LO)

AGND

ACH6 (ACH6 HI)

ACH14 (ACH6 LO)

AGND

ACH7 (ACH7 HI)

ACH15 (ACH7 LO)

XDAC3

28

61

**

60

26

**

25

58

**

57

23

56

SGND 62

POSREF (reserved for self-calibration) 20

XDAC2 55

NEGREF (reserved for self-calibration) 54

AGND

XDAC0

AGND

XDAC1

AGND

XAPCR

GND

**

22

**

21

**

2

**

EGND †

*

Digital common ground pins on the SCSI connector are: 35, 36, and 40.

**

Analog common ground pins on the SCSI connector are: 24, 27, 29, 32, 59, 64, and 67.

† EGND is connected to the SCSI connector shell.

15

USB-2537 User's Guide Installing the USB-2537

40-pin header connector pin outs

Analog channels pin out (J5 and J6)

This edge of the header is closest to the center of the USB-

2537. Pins 2 and 40 are labeled on the board silkscreen.

Analog channel Pin

ACH27 1

ACH26 3

AGND 5

ACH3 7

ACH2 9

ACH17 11

ACH16 13

ACH1 15

ACH0 17

AGND 19

ACH23 21

ACH22 23

ACH7 25

ACH6 27

AGND 29

ACH29 31

ACH28 33

ACH13 35

ACH12 37

AGND 39

J5

40-pin header connectors pin out (labeled J5 and J6)

64-channel single-ended mode

Pin Analog channel Analog channel Pin

2 ACH19 ACH43 1

4 ACH18 ACH35 3

6 AGND

8 ACH11

10 ACH10

12 ACH25

14 ACH24

16 ACH9

18 ACH8

20 AGND

22 ACH31

24 ACH30

26 ACH15

28 ACH14

30 ACH21

32 ACH20

34 ACH5

36 ACH4

38 AGND

40 AGND

AGND 5

ACH42 7

ACH34 9

AGND 11

ACH41 13

ACH33 15

ACH40 17

ACH32 19

ACH47 21

ACH39 23

ACH46 25

ACH38 27

AGND 29

ACH45 31

ACH37 33

ACH44 35

ACH36 37

AGND 39

J6

Pin Analog channel

2 ACH59

4 ACH51

6 ACH58

8 ACH50

10 ACH57

12 ACH49

14 ACH56

16 ACH48

18 AGND

20 ACH63

22 ACH55

24 AGND

26 ACH62

28 ACH54

30 ACH61

32 ACH53

34 ACH60

36 ACH52

38 AGND

40 AGND

16

USB-2537 User's Guide Installing the USB-2537

Analog channel Pin

ACH11 LO 1

ACH10 LO 3

AGND 5

ACH3 HI 7

ACH2 HI 9

ACH9 HI 11

ACH8 HI 13

ACH1 HI 15

ACH0 HI 17

AGND 19

ACH15 HI 21

ACH14 HI 23

ACH7 HI 25

ACH6 HI 27

AGND 29

ACH13 LO 31

ACH12 LO 33

ACH5 LO 35

ACH4 LO 37

AGND 39

J5

40-pin header connectors pin out (labeled J5 and J6)

32-channel differential mode

channel Analog channel Pin

6 AGND

20 AGND

38 AGND

40 AGND

ACH19 LO 1

ACH19 HI 3

AGND 5

ACH18 LO 7

ACH18 HI 9

AGND 11

ACH17 LO 13

ACH17 HI 15

ACH16 LO 17

ACH16 HI 19

ACH23 LO 21

ACH23 HI 23

ACH22 LO 25

ACH22 HI 27

AGND 29

ACH21 LO 31

ACH21 HI 33

ACH20 LO 35

ACH20 HI 37

AGND 39

J6

18 AGND

24 AGND

38 AGND

40 AGND

17

USB-2537 User's Guide Installing the USB-2537

Digital ports, counters, timers, DACs, triggers, and pacer clocks pin out (J7 and J8)

You can use the 40-pin connector headers labeled J7 and J8 to connect digital ports, counters, timers, DACs, triggers, pacer clocks, and other signals.

Digital channel Pin

USB-2537 40-pin header connectors pin out (labeled J7 and J8)

J7 channel

Signal

Pin

J8

GND 1

A0 3

A1 5

A2 7

A3 9

GND 11

B0 13

B1 15

B2 17

B3 19

GND 21

C0 23

C1 25

C2 27

C3 29

GND 31

TMR0 33

CNT0 35

CNT2 37

GND 39

2 XAPCR

4 A4

6 A5

8 A6

10 A7

12 TTL TRG

14 B4

16 B5

18 B6

20 B7

22 +5 V

24 C4

26 C5

28 C6

30 C7

32 TMR1

34 CNT1

36 CNT3

38 GND

40 GND

+13 V 1

NC 3

AGND 5

XDAC0 7

XDAC1 9

AGND 11

SelfCal 13

AGND 15

TTL TRG 17

XAPCR 19

GND (digital) 21

NC 23

+5 V 25

NC 27

NC 29

NC 31

NC 33

NC 35

NC 37

NC 39

Pin Signal

4 NC

6 AGND

8 XDAC2

10 XDAC3

12 AGND

14 SGND

16 AGND

18 XDPCR

20 GND (digital)

22 GND (digital)

24 NC

26 AUX PWR

28 NC

30 NC

32 NC

34 NC

36 NC

38 NC

40 NC

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USB-2537 User's Guide Installing the USB-2537

Using C40FF-x cables to obtain 40-pin female connectors

In this example, a C40FF-x cable is connected to all of the 40-pin headers (J5, J6, J7, and J8). The result is four female 40-pin connectors that together have more signal connectivity than the SCSI connector.

40-pin female connectors

C40FF-x header cables

USB cable

Figure 1. Four C40FF-x cables connected to J5 through J8 40-pin connectors

In all scenarios, a USB cable (MCC p/n CA-USB2.0) is used to connect the USB-2537 to a USB port on the host PC.

Four-channel TC terminal pin out (TB7)

You can use the TB7 terminal block to connect up to four thermocouples. The first TC channel uses ACH0

(analog channel 0) for its positive (+) lead, and ACH8 for its negative (-) lead. The second TC channel uses

ACH1 and ACH9, and so on, as indicated in Figure 2.

Standoff

Figure 2. TC terminal pin out (labeled TB7)

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USB-2537 User's Guide Installing the USB-2537

Cabling

Use a CA-68-3R 68-pin ribbon expansion cable (

Figure 3 ), or a CA-68-3S (3-foot) or CA-68-6S (6-foot) 68-pin

shielded expansion cable (

Figure 4 ) to connect signals to the USB-2537's 68-pin SCSI connector.

34 68

34 68

1 35

The stripe identifies pin # 1

Figure 3. CA-68-3R cable

1 35

34 68

34 68

1 35

1 35

Figure 4. CA-68-3S and CA-68-6S cable

Use one or more C40FF-x- ribbon cable(s) ( Figure 5 ) to connect signals to one or more of the USB-2537's 40-

pin header connectors.

2

1

The red stripe identifies pin # 1

2

1

40

39

40-pin Female

IDC Connector

Figure 5. C40FF-x cable

40

39

40-pin Female

IDC Connector

20

USB-2537 User's Guide Installing the USB-2537

Field wiring and signal termination

You can use the following Measurement Computing screw terminal board to terminate field signals and route them into the USB-2537 board using the CA-68-3R, CA-68-3S, or CA-68-6S cable:

ƒ

TB-100

: Termination board with screw terminals. Details on this product are available on our web site at www.mccdaq.com/cbicatalog/cbiproduct.asp?dept_id=98&pf_id=1787.

A 19-inch rack mount kit (

RM-TB-100)

for the TB-100 termination board is also available. Details on this product are available on our web site at www.mccdaq.com/cbicatalog/cbiproduct.asp?dept_id=98&pf_id=1786 .

You can use the following screw terminal board with the C40FF-x cable.

ƒ

CIO-MINI40

: 40-pin screw terminal board. Details are available on our web site at www.mccdaq.com/cbicatalog/cbiproduct.asp?dept_id=102&pf_id=257 .

Using multiple USB-2537s per PC

USB-2537 features can be replicated up to four times, as up to four devices can be connected a single host PC.

The serial number on each USB-2537 distinguishes one from another. You can operate multiple USB-2537 boards synchronously. To do this, set up one USB-2537 with the pacer pin you want to use (XAPCR or

XDPCR) configured for output. Set up the USB-2537 boards you want to synchronize to this board with the pacer pin you want to use (XAPCR or XDPCR) configured for input. Wire the pacer pin configured for output to each of the pacer input pins that you want to synchronize.

21

Chapter 3

Functional Details

This chapter contains detailed information on all of the features available from the board, including:

ƒ a diagram and explanations of physical board components

ƒ a functional block diagram

ƒ information on how to use the signals generated by the board

ƒ diagrams of signals using default or conventional board settings

USB-2537 components

These USB-2537 components are shown in Figure 6 .

ƒ

One USB port

ƒ One external power connector

ƒ One 68-pin SCSI connector

ƒ Four 40-pin headers (J5, J6, J7, and J8)

ƒ

One four-channel TC screw terminal block

ƒ Two LED indicators (USB and power)

J6

J5 TB7

J8

J7

P5

External power supply connector

USB 2.0 port

USB LED

Power LED

Figure 6. USB-2537 components

22

USB-2537 User's Guide Functional Details

SCSI - 68 pin (P5) connector

The 68-pin SCSI connector includes pins for the following:

ƒ 16 single-ended/eight differential analog inputs (64 single-ended/32 differential analog inputs available only from J5 and J6 40-pin connectors)

ƒ Four analog outputs

ƒ 24 digital I/O

ƒ Four counter inputs

ƒ Two timer outputs

ƒ Input scan pacer clock I/O

ƒ

Output scan pacer clock I/O

ƒ TTL trigger

ƒ self calibration

ƒ +5 VDC

ƒ analog commons

ƒ digital commons

40-pin headers (J5, J6, J7, J8)

Four 40-pin headers (J5 through J8) provide alternative connections to the signals of the SCSI connector.

Up to 64 single-ended/32 differential analog inputs are available from J5 and J6 connectors as well.

You can get a female connector for each header by connecting a C40FF-x cable (40-pin header to female 40-pin header) to each header.

9-slot screw terminal (TB7)

You can use the on-board screw terminal connector (TB7) to connect up to four TC inputs. TB7 uses the following analog channels to obtain its four differential channels:

ƒ TC CH0: CH 0 (+); CH 8 (-)

ƒ TC CH1: CH 1 (+); CH 9 (-)

ƒ TC CH2: CH 2 (+); CH 10 (-)

ƒ TC CH3: CH 3 (+); CH 11 (-)

When using the thermocouple channels, do not connect signals to the associated channels on the SCSI connector or J5.

External power connector

Although the USB-2537 is powered by a USB port on a host PC, an external power connector is available when the host PC’s USB port cannot supply adequate power, or if you prefer to use a separate power source.

Connect the optional PS-9V1AEPS-2500 power supply to the external power supply connector. This power supply plugs into a standard 120 VAC outlet and supplies 9 VDC, 1 A power to the USB-2537.

23

USB-2537 User's Guide Functional Details

USB-2537 block diagram

Figure 7 is a simplified block diagram of the USB-2537. This board provides all of the functional elements

shown in the figure.

Four 16-bit digital-to-analog converters

16-bit,

1 MHz

A/D converter

A

A

A

Figure 7. USB-2537 functional block diagram

24

USB-2537 User's Guide Functional Details

Synchronous I/O – mixing analog, digital, and counter scanning

The USB-2537 can read analog, digital, and counter inputs, while generating up to four analog outputs and digital pattern outputs at the same time. Digital and counter inputs do not affect the overall A/D rate because these inputs use no time slot in the scanning sequencer.

For example, one analog input channel can be scanned at the full 1 MHz A/D rate along with digital and counter input channels. Each analog channel can have a different gain, and counter and digital channels do not need additional scanning bandwidth as long as there is at least one analog channel in the scan group.

Digital input channel sampling is not done during the "dead time" of the scan period where no analog sampling is being done either.

Analog input

The USB-2537 has a 16-bit, 1-MHz A/D coupled with 64 single-ended, or 32 differential analog inputs. Seven software programmable ranges provide inputs from ±10 V to ±100 mV full scale.

Analog input scanning

The USB-2537 has several scanning modes to address various applications. You can load the 512-location scan buffer with any combination of analog input channels. All analog input channels in the scan buffer are measured sequentially at 1 µs per channel by default.

For example, in the fastest mode, with a 1 µs settling time for the acquisition of each channel, a single analog channel can be scanned continuously at 1 MS/s; two analog channels can be scanned at 500 kS/s each; 16 analog input channels can be scanned at 62.5 kS/s.

Settling time

For most applications, leave the settling time at its default of 1 µs.

However, if you are scanning multiple channels, and one or more channels are connected to a high-impedance source, you may get better results by increasing the settling time. Remember that increasing the settling reduces the maximum acquisition rate.

You can set the settling time to 1 µs, 5 µs, 10 µs, or 1 ms.

Example: Analog channel scanning of voltage inputs

Figure 8 shows a simple acquisition. The scan is programmed pre-acquisition and is made up of six analog

channels (Ch0, Ch1, Ch3, Ch4, Ch6, and Ch7). Each of these analog channels can have a different gain. The acquisition is triggered and the samples stream to the PC. Using the default settling time, each analog channel requires one microsecond of scan time—therefore the scan period can be no shorter than 6 µs for this example.

The scan period can be made much longer than 6 µs—up to 1 s. The maximum scan frequency is 1 divided by

6 µs, or 166,666 Hz.

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USB-2537 User's Guide Functional Details

Figure 8. Analog channel scan of voltage inputs example

Example: Analog channel scanning of voltage and temperature inputs

Figure 9 shows a programmed pre-acquisition scan made up of six analog channels (Ch0, Ch1, Ch5, Ch11,

Ch12, Ch13). Each of these analog channels can have a different gain. You can program channels 0 and 1 to directly measure TCs.

In this mode, oversampling is programmable up to 16384 oversamples per channel in the scan group. When oversampling is applied, it is applied to all analog channels in the scan group, including temperature and voltage channels. Digital channels are not oversampled.

If you want 256 oversamples, then each analog channel in the scan group takes 256 µs, and the returned 16-bit value represents an average of 256 consecutive 1 µs samples of that channel. The acquisition is triggered and

16-bit values—each representing an average of 256—stream to the PC via the USB cable. Since two of the channels in the scan group are temperature channels, you need the acquisition engine to read a cold-junctioncompensation (CJC) temperature every scan.

Figure 9. Analog channel scanning of voltage and temperature inputs example

Since the targeted number of oversamples is 256 in this example, each analog channel in the scan group requires 256 microseconds to return one 16-bit value. The oversampling is also done for CJC temperature measurement channels, making the minimum scan period for this example 7 X 256 µs, or 1792 µs. The maximum scan frequency is the inverse of this number, 558 Hz.

For accurate measurements, you must associate TC and CJC channels properly

The TC channels must immediately follow their associated CJC channels in the channel array. For accurate TC readings, associate CJC0 with TC0, CJC1 with TC1 and TC2, and CJC2 with TC3.

Example: Analog and digital scanning, once per scan mode

The scan is programmed pre-acquisition and is made up of six analog channels (Ch0, Ch2, Ch5, Ch11, Ch13,

Ch15) and four digital channels (16-bits of digital IO, three counter inputs.) Each of the analog channels can have a different gain.

26

USB-2537 User's Guide Functional Details

The acquisition is triggered and the samples stream to the PC via the USB cable. Each analog channel requires one microsecond of scan time. Therefore, the scan period can be no shorter than 6 µs for this example. All of the digital channels are sampled at the start of scan and do not require additional scanning bandwidth as long as there is at least one analog channel in the scan group. The scan period can be made much longer than 6 µs, up to

1 second. The maximum scan frequency is one divided by 6 µs, or 166,666 Hz.

Figure 10. Analog and digital scanning, once per scan mode example

The counter channels may return only the lower 16-bits of count value if that is sufficient for the application.

They could also return the full 32-bit result if necessary. Similarly, the digital input channel could be the full 24 bits if desired or only eight bits if that is sufficient. If the three counter channels are all returning 32-bit values and the digital input channel is returning a 16-bit value, then 13 samples are being returned to the PC every scan period, with each sample being 16-bits. The 32-bit counter channels are divided into two 16-bit samples—one for the low word, and the other for the high word. If the maximum scan frequency is 166,666 Hz, then the data bandwidth streaming into the PC is 2.167 MS/s. Some slower PCs may have a problem with data bandwidths greater than 6 MS/s.

The USB-2537 has an onboard 1 MS buffer for acquired data.

Example: Sampling digital inputs for every analog sample in a scan group

The scan is programmed pre-acquisition and is made up of six analog channels (Ch0, Ch2, Ch5, Ch11, Ch13,

Ch15) and four digital channels (16-bits of digital input, three counter inputs.) Each of the analog channels can have a different gain.

The acquisition is triggered and the samples stream to the PC via the USB cable. Each analog channel requires one microsecond of scan time therefore the scan period can be no shorter than 6 µs for this example. All of the digital channels are sampled at the start of scan and do not require additional scanning bandwidth as long as there is at least one analog channel in the scan group. The 16-bits of digital input are sampled for every analog sample in the scan group. This allows up to 1 MHz digital input sampling while the 1 MHz analog sampling bandwidth is aggregated across many analog input channels.

The scan period can be made much longer than 6 µs—up to 1 second. The maximum scan frequency is one divided by 6 µs, or 166,666 Hz. Note that digital input channel sampling is not done during the "dead time" of the scan period where no analog sampling is being done either.

27

USB-2537 User's Guide Functional Details

Figure 11. Analog and digital scanning, once per scan mode example

If the three counter channels are all returning 32-bit values and the digital input channel is returning a 1-bit value, then 18 samples are returned to the PC every scan period, with each sample being 16-bits. Each 32-bit counter channel is divided into two 16-bit samples—one for the low word and the other for the high word. If the maximum scan frequency is 166,666 Hz, then the data bandwidth streaming into the PC is 3 MS/s. Some slower

PCs may have a problem with data bandwidths greater than 6 MS/s.

The USB-2537 has an onboard 1 MS buffer for acquired data.

Thermocouple input

You can configure up to four analog inputs on the USB-2537 to accept a TC input. Built-in cold-junction sensors are provided for each of the screw-terminal connectors, and any TC type can be attached to any of the four thermocouple channels.

When measuring TCs, the USB-2537 can operate in an averaging mode, taking multiple readings on each channel, applying digital filtering and cold-junction compensation, and then converting the readings to temperature.

As a result, the USB-2537 measures channels with TCs attached at a rate from 50 Hz to 10 kHz, depending on how much over-sampling is selected.

Additionally, a rejection frequency can be specified in which over sampling occurs during one cycle of either

50 Hz or 60 Hz, providing a high level of 50 Hz or 60 Hz rejection.

Tips for making accurate temperature measurements

ƒ

Use as much oversampling as possible.

ƒ Warm up the USB-2537 for 60 minutes—including TC wires—so that it is thermally stabilized. This warm-up time enables the CJC thermistors to more accurately measure the junction at the terminal block.

ƒ Make sure the surrounding environment is thermally stabilized and ideally around 20 °C to 30 °C. If the board’s ambient temperature is changing due to a local heating or cooling source, then the TC junction temperature may be changing and the CJC thermistor will have a larger error.

ƒ Use small-diameter, instrument-grade TC wire. Small diameter TC wire has less effect on the TC junction at the terminal block because less heat is transferred from the ambient environment to the junction.

ƒ Use shielded TC wire (see "

Shielding " on page 29) with the shield connected to analog common to reduce

noise. The USB-2537 has several analog common pins on both the 68-pin connector and the 40-pin connectors, and the TB-7 has one analog common screw terminal.

You can also minimize the effect of noise by averaging readings (see "

Averaging " on page 29), or

combining both shielding and averaging.

Refer to "

68-pin SCSI connector differential and single-ended pin outs (P5) " on page 13, "

40-pin header connector pin outs " on page 16, and "

Four-channel TC terminal pin out (TB7) " on page 19 for the locations

of these analog common pins.

28

USB-2537 User's Guide Functional Details

ƒ Make sure the USB-2537 is mounted on a flat surface.

ƒ

Be careful to avoid loading down the digital outputs too heavily (>1 mA). Heavy load down causes significant heat generation inside the unit and increase the CJC thermistor error.

Shielding

Use shielded TC wire with the shield connected to analog common to further reduce noise.

The USB-2537 has one analog common screw-terminal on TB7 and several analog common pins on the headers

(see "

Connecting the board for I/O operations " starting on page 12). You can connect the shield of a shielded

thermocouple to one of the analog commons. When this connection is made, leave the shield at the other end of the thermocouple unconnected.

Caution! Connecting the shield to common at both ends results in a ground loop.

Averaging

Certain acquisition programs apply averaging after several samples have been collected. Depending on the nature of the noise, averaging can reduce noise by the square root of the number of averaged samples.

Although averaging can be effective, it suffers from several drawbacks.

ƒ Noise in measurements only decreases as the square root of the number of measurements—reducing RMS noise significantly may require many samples. Thus, averaging is suited to low-speed applications that can provide many samples.

ƒ Only random noise is reduced or eliminated by averaging. Averaging does not reduce or eliminate periodic signals.

Analog output

The USB-2537 has four 16-bit, 1 MHz analog output channels.

The channels have an output range of -10V to +10V. Each D/A output can continuously output a waveform at up to 1 MHz. In addition, a program can asynchronously output a value to any of the D/A channels for nonwaveform applications, assuming that the D/A is not already being used in the waveform output mode.

When used to generate waveforms, you can clock the D/As in several different modes.

ƒ

Internal output scan clock

: The on-board programmable clock can generate updates ranging from 1 Hz to

1 MHz.

ƒ

External output scan clock (XDPCR)

: A user-supplied external clock.

ƒ

Internal input scan pacer clock

: The internal ADC pacer clock can pace both the D/A and the analog input.

ƒ

External input scan pacer clock (XAPCR)

: The external ADC pacer clock can pace both the D/A and the analog input.

Example: Analog channel scanning of voltage inputs and streaming analog outputs

The example shown in Figure 12 adds four DACs and a 16-bit digital pattern output paced by the input scan

clock to the example presented in

Figure 8 .

29

USB-2537 User's Guide Functional Details

Figure 12. Analog channel scan of voltage inputs and streaming analog outputs example

This example updates all DACs and the 16-bits of digital I/O. These updates happen at the same time as the acquisition pacer clock—also called the input scan clock. All DACs and the 16-bits of pattern digital output are updated at the beginning of each scan.

Due to the time it takes to shift the digital data out to the DACs, plus the actual settling time of the digital-to- analog conversion, the DACs actually take up to 4 µs after the start of scan to settle on the updated value.

The data for the DACs and pattern digital output comes from a PC-based buffer. The data is streamed across the

USB2 bus to the USB-2537.

In this example, the outputs are updated by the input scan clock, but you can also update the DACs and pattern digital output with the output scan clock—either internally-generated or externally-applied. In this scenario, the acquisition input scans are not synchronized to the analog outputs or pattern digital outputs.

Digital I/O

Twenty-four TTL-level digital I/O lines are included in each USB-2537. You can program digital I/O in 8-bit groups as either inputs or outputs and scan them in several modes (see "

Digital input scanning " below). You can

access input ports asynchronously from the PC at any time, including when a scanned acquisition is occurring.

Digital input scanning

Digital input ports can be read asynchronously before, during, or after an analog input scan.

Digital input ports can be part of the scan group and scanned along with analog input channels. Two synchronous modes are supported when digital inputs are scanned along with analog inputs.

Refer to " Example 4: Sampling digital inputs for every analog sample in a scan group

" on page 27 for more

information.

In both modes, adding digital input scans has no affect on the analog scan rate limitations.

If no analog inputs are being scanned, the digital inputs can sustain rates up to 4 MHz. Higher rates—up to

12 MHz—are possible depending on the platform and the amount of data being transferred.

30

USB-2537 User's Guide Functional Details

Digital outputs and pattern generation

Digital outputs can be updated asynchronously at anytime before, during, or after an acquisition. You can use two of the 8-bit ports to generate a digital pattern at up to 4 MHz. The USB-2537 supports digital pattern generation. The digital pattern can be read from PC RAM.

Higher rates—up to 12 MHz—are possible depending on the platform and the amount of data being transferred.

Digital pattern generation is clocked using an internal clock. The on-board programmable clock generates updates ranging from once every 1 second to 1 MHz, independent of any acquisition rate.

Triggering

Triggering can be the most critical aspect of a data acquisition application. The USB-2537 supports the following trigger modes to accommodate certain measurement situations.

Hardware analog triggering

The USB-2537 uses true analog triggering in which the trigger level you program sets an analog DAC, which is then compared in hardware to the analog input level on the selected channel. This guarantees an analog trigger latency that is less than 1 µs.

You can select any analog channel as the trigger channel, but the selected channel must be the first channel in the scan. You can program the trigger level, the rising or falling edge, and hysteresis.

A note on the hardware analog level trigger and comparator change state

When analog input voltage starts near the trigger level, and you are performing a rising or falling hardware analog level trigger, the analog level comparator may have already tripped before the sweep was enabled. If this is the case, the circuit waits for the comparator to change state. However, since the comparator has already changed state, the circuit does not see the transition.

To resolve this problem, do the following:

1. Set the analog level trigger to the threshold you want.

2. Apply an analog input signal that is more than 2.5% of the full-scale range away from the desired

threshold. This ensures that the comparator is in the proper state at the beginning of the acquisition.

3. Bring the analog input signal toward the desired threshold. When the input signal is at the threshold

(± some tolerance) the sweep will be triggered.

4. Before re-arming the trigger, move the analog input signal to a level that is more than 2.5% of the full-scale range away from the desired threshold.

For example, if you are using the ±2 V full-scale range (gain = 5), and you want to trigger at +1 V on the rising edge, you would set the analog input voltage to a start value that is less than +0.9 V (1 V – (2 V * 2 * 2.5%)).

Digital triggering

A separate digital trigger input line is provided (TTL TRG), allowing TTL-level triggering with latencies guaranteed to be less than 1 µs. You can program both of the logic levels (1 or 0) and the rising or falling edge for the discrete digital trigger input.

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USB-2537 User's Guide Functional Details

Software-based triggering

The three software-based trigger modes differ from hardware analog triggering and digital triggering because the readings—analog, digital, or counter—are checked by the PC in order to detect the trigger event.

Analog triggering

You can select any analog channel in the scan as the trigger channel. You can program the trigger level, the rising or falling edge, and hysteresis.

Pattern triggering

You can select any scanned digital input channel pattern to trigger an acquisition, including the ability to mask or ignore specific bits.

Counter triggering

You can program triggering to occur when one of the counters meets or exceeds a set value, or is within a range of values. You can program any of the included counter channels as the trigger source.

Software-based triggering usually results in a long period of inactivity between the trigger condition being detected and the data being acquired. However, the USB-2537 avoids this situation by using pre-trigger data.

When software-based-triggering is used, and the PC detects the trigger condition—which may be thousands of readings after the actual occurrence of the signal—the USB-2537 driver automatically looks back to the location in memory where the actual trigger-causing measurement occurred, and presents the acquired data that begins at the point where the trigger-causing measurement occurs. The maximum inactive period in this mode equals one scan period.

Set pre-trigger > 0 when using counter as trigger source

When using a counter for a trigger source, you should use a pre-trigger with a value of at least 1. Since all counters start at zero with the first scan, there is no valid reference in regard to rising or falling edge. Setting a pre-trigger to 1 or more ensures that a valid reference value is present, and that the first trigger will be legitimate.

Stop trigger modes

You can use any of the software trigger modes explained previously to stop an acquisition.

For example, you can program an acquisition to begin on one event—such as a voltage level—and then stop on another event—such as a digital pattern.

Pre-triggering and post-triggering modes

The USB-2537 supports four modes of pre-triggering and post-triggering, providing a wide-variety of options to accommodate any measurement requirement.

When using pre-trigger, you must use software-based triggering to initiate an acquisition.

No pre-trigger, post-trigger stop event

In this simple mode, data acquisition starts when the trigger is received, and the acquisition stops when the stoptrigger event is received.

32

USB-2537 User's Guide Functional Details

Fixed pre-trigger with post-trigger stop event

In this mode, you set the number of pre-trigger readings to acquire. The acquisition continues until a stoptrigger event occurs.

No pre-trigger, infinite post-trigger

In this mode, no pre-trigger data is acquired. Instead, data is acquired beginning with the trigger event, and is terminated when you issue a command to halt the acquisition.

Fixed pre-trigger with infinite post-trigger

You set the amount of pre-trigger data to acquire. Then, the system continues to acquire data until the program issues a command to halt acquisition.

Counter inputs

Four 32-bit counters are built into the USB-2537. Each counter accepts frequency inputs up to 20 MHz.

USB-2537 counter channels can be configured as standard counters or as multi-axis quadrature encoders.

The counters can concurrently monitor time periods, frequencies, pulses, and other event driven incremental occurrences directly from pulse-generators, limit switches, proximity switches, and magnetic pick-ups.

Counter inputs can be read asynchronously under program control, or synchronously as part of an analog or digital scan group.

When reading synchronously, all counters are set to zero at the start of an acquisition. When reading asynchronously, counters may be cleared on each read, count up continually, or count until the 16 bit or 32 bit limit has been reached. See the counter mode descriptions below.

Figure 13. Typical USB-2537 counter channel

Mapped channels

A mapped channel is one of four counter input signals that can get multiplexed into a counter module. The mapped channel can participate with the counter's input signal by gating the counter, latching the counter, and so on. The four possible choices for the mapped channel are the four counter input signals (post-debounce).

A mapped channel can be used to:

ƒ gate the counter

ƒ decrement the counter

ƒ latch the current count to the count register

Usually, all counter outputs are latched at the beginning of each scan within the acquisition. However, you can use a second channel—known as the mapped channel—to latch the counter output.

33

USB-2537 User's Guide Functional Details

Counter modes

A counter can be asynchronously read with or without clear on read. The asynchronous read-signals strobe when the lower 16-bits of the counter are read by software. The software can read the counter's high 16-bits some time later after reading the lower 16-bits. The full 32-bit result reflects the timing of the first asynchronous read strobe.

Totalize mode

The Totalize mode allows basic use of a 32-bit counter. While in this mode, the channel's input can only increment the counter upward. When used as a 16-bit counter (counter low), one channel can be scanned at the

12 MHz rate. When used as a 32-bit counter (counter high), two sample times are used to return the full 32-bit result. Therefore a 32-bit counter can only be sampled at a 6 MHz maximum rate. If you only want the upper 16 bits of a 32-bit counter, then you can acquire that upper word at the 12 MHz rate.

The counter counts up and does not clear on every new sample. However, it does clear at the start of a new scan command.

The counter rolls over on the 16-bit (counter low) boundary, or on the 32-bit (counter high) boundary.

Clear on read mode

The counter counts up and is cleared after each read. By default, the counter counts up and only clears the counter at the start of a new scan command. The final value of the counter —the value just before it was cleared—is latched and returned to the USB-2537.

Stop at the top mode

The counter stops at the top of its count. The top of the count is FFFF hex (65,535) for the 16-bit mode, and

FFFFFFFF hex (4,294,967,295) for the 32-bit mode.

32-bit or 16-bit

Sets the counter type to either 16-bits or 32-bits. The type of counter only matters if the counter is using the stop at the top mode—otherwise, this option is ignored.

Latch on map

Sets the signal on the mapped counter input to latch the count.

By default, the start of scan signal—a signal internal to the USB-2537 pulses once every scan period to indicate the start of a scan group—latches the count, so the count is updated each time a scan is started.

Gating "on" mode

Sets the gating option to "on" for the mapped channel, enabling the mapped channel to gate the counter.

Any counter can be gated by the mapped channel. When the mapped channel is high, the counter is enabled.

When the mapped channel is low, the counter is disabled (but holds the count value). The mapped channel can be any counter input channel other than the counter being gated.

Decrement "on" mode

Sets the counter decrement option to "on" for the mapped channel. The input channel for the counter increments the counter, and you can use the mapped channel to decrement the counter.

34

USB-2537 User's Guide Functional Details

Debounce modes

Each channel's output can be debounced with 16 programmable debounce times from 500 ns to 25.5 ms.

The debounce circuitry eliminates switch-induced transients typically associated with electro-mechanical devices including relays, proximity switches, and encoders.

There are two debounce modes, as well as a debounce bypass, as shown in

Figure 14 . In addition, the signal

from the buffer can be inverted before it enters the debounce circuitry. The inverter is used to make the input rising-edge or falling-edge sensitive.

Edge selection is available with or without debounce. In this case the debounce time setting is ignored and the input signal goes straight from the inverter or inverter bypass to the counter module.

There are 16 different debounce times. In either debounce mode, the debounce time selected determines how fast the signal can change and still be recognized.

The two debounce modes are trigger after stable and trigger before stable. A discussion of the two modes follows.

Figure 14. Debounce model block diagram

Trigger after stable mode

In the trigger after stable mode, the output of the debounce module does not change state until a period of stability has been achieved. This means that the input has an edge, and then must be stable for a period of time equal to the debounce time.

Figure 15. Debounce module – trigger after stable mode

The following time periods (T1 through T5) pertain to Figure 15 . In trigger after stable mode, the input signal

to the debounce module is required to have a period of stability after an incoming edge, in order for that edge to be accepted (passed through to the counter module.) The debounce time for this example is equal to T2 and T5.

ƒ T1 – In the example above, the input signal goes high at the beginning of time period T1, but never stays high for a period of time equal to the debounce time setting (equal to T2 for this example.)

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USB-2537 User's Guide Functional Details

ƒ T2 – At the end of time period T2, the input signal has transitioned high and stayed there for the required amount of time—therefore the output transitions high. If the input signal does not stabilize in the high state long enough, no transition would have appeared on the output and the entire disturbance on the input would have been rejected.

ƒ T3 – During time period T3, the input signal remained steady. No change in output is seen.

ƒ T4 – During time period T4, the input signal has more disturbances and does not stabilize in any state long enough. No change in the output is seen.

ƒ T5 – At the end of time period T5, the input signal has transitioned low and stayed there for the required amount of time—therefore the output goes low.

Trigger before stable mode

In the trigger before stable mode, the output of the debounce module immediately changes state, but will not change state again until a period of stability has passed. For this reason the mode can be used to detect glitches.

Figure 16. Debounce module – Trigger before stable mode

The following time periods (T1 through T6) pertain to the above drawing.

ƒ T1 – In the illustrated example, the input signal is low for the debounce time (equal to T1); therefore when the input edge arrives at the end of time period T1, it is accepted and the output (of the debounce module) goes high. Note that a period of stability must precede the edge in order for the edge to be accepted.

ƒ T2 – During time period T2, the input signal is not stable for a length of time equal to T1 (the debounce time setting for this example.) Therefore, the output stays "high" and does not change state during time period T2.

ƒ T3 – During time period T3, the input signal is stable for a time period equal to T1, meeting the debounce requirement. The output is held at the high state. This is the same state as the input.

ƒ T4 – At anytime during time period T4, the input can change state. When this happens, the output will also change state. At the end of time period T4, the input changes state, going low, and the output follows this action [by going low].

ƒ T5 – During time period T5, the input signal again has disturbances that cause the input to not meet the debounce time requirement. The output does not change state.

ƒ T6 – After time period T6, the input signal has been stable for the debounce time and therefore any edge on the input after time period T6 is immediately reflected in the output of the debounce module.

Debounce mode comparisons

Figure 17 shows how the two modes interpret the same input signal, which exhibits glitches. Notice that the

trigger before stable mode recognizes more glitches than the trigger after stable mode. Use the bypass option to achieve maximum glitch recognition.

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USB-2537 User's Guide Functional Details

Figure 17. Example of two debounce modes interpreting the same signal

Debounce times should be set according to the amount of instability expected in the input signal. Setting a debounce time that is too short may result in unwanted glitches clocking the counter. Setting a debounce time too long may result in an input signal being rejected entirely. Some experimentation may be required to find the appropriate debounce time for a particular application.

To see the effects of different debounce time settings, simply view the analog waveform along with the counter output. This can be done by connecting the source to an analog input.

Use trigger before stable mode when the input signal has groups of glitches and each group is to be counted as one. The trigger before stable mode recognizes and counts the first glitch within a group but rejects the subsequent glitches within the group if the debounce time is set accordingly. The debounce time should be set to encompass one entire group of glitches as shown in the following diagram.

Figure 18.Optimal debounce time for trigger before stable mode

Trigger after stable mode behaves more like a traditional debounce function: rejecting glitches and only passing state transitions after a required period of stability. Trigger after stable mode is used with electro-mechanical devices like encoders and mechanical switches to reject switch bounce and disturbances due to a vibrating encoder that is not otherwise moving. The debounce time should be set short enough to accept the desired input pulse but longer than the period of the undesired disturbance as shown in

Figure 19 .

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USB-2537 User's Guide Functional Details

Figure 19. Optimal debounce time for trigger after stable mode

Encoder mode

Rotary shaft encoders are frequently used with CNC equipment, metal-working machines, packaging equipment, elevators, valve control systems, and in a multitude of other applications in which rotary shafts are involved.

The encoder mode allows the USB-2537 to make use of data from optical incremental quadrature encoders. In encoder mode, the USB-2537 accepts single-ended inputs. When reading phase A, phase B, and index Z signals, the USB-2537 provides positioning, direction, and velocity data.

The USB-2537 can receive input from up to two encoders.

The USB-2537 supports quadrature encoders with a 16-bit (counter low) or a 32-bit (counter high) counter,

20 MHz frequency, and X1, X2, and X4 count modes. With only phase A and phase B signals, two channels are supported; with phase A, phase B, and index Z signals, 1 channel is supported. Each input can be debounced from 500 ns to 25.5 ms (total of 16 selections) to eliminate extraneous noise or switch induced transients.

Encoder input signals must be within -5 V to +10 V and the switching threshold is TTL (1.3V).

Quadrature encoders generally have three outputs: A, B, and Z. The A and B signals are pulse trains driven by an optical sensor inside the encoder. As the encoder shaft rotates, a laminated optical shield rotates inside the encoder. The shield has three concentric circular patterns of alternating opaque and transparent windows through which an LED shines. There is one LED and one phototransistor for each of the concentric circular patterns. One phototransistor produces the A signal, another phototransistor produces the B signal and the last phototransistor produces the Z signal. The concentric pattern for A has 512 window pairs (or 1024, 4096, etc.)

When using a counter for a trigger source, use a pre-trigger with a value of at least 1. Since all counters start at zero with the initial scan, there is no valid reference in regard to rising or falling edge. Setting a pre-trigger to

1 or more ensures that a valid reference value is present, and that the first trigger is legitimate.

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USB-2537 User's Guide Functional Details

The concentric pattern for B has the same number of window pairs as A—except that the entire pattern is rotated by 1/4 of a window-pair. Thus the B signal is always 90 degrees out of phase from the A signal. The A and B signals pulse 512 times (or 1024, 4096, etc.) per complete rotation of the encoder.

The concentric pattern for the Z signal has only one transparent window and therefore pulses only once per complete rotation. Representative signals are shown in the following figure.

A

B

Z

Figure 20. Representation of quadrature encoder outputs: A, B, and Z

As the encoder rotates, the A (or B) signal indicates the distance the encoder has traveled. The frequency of A

(or B) indicates the velocity of rotation of the encoder. If the Z signal is used to zero a counter (that is clocked by A) then that counter gives the number of pulses the encoder has rotated from its reference. The Z signal is a reference marker for the encoder. It should be noted that when the encoder is rotating clockwise (as viewed from the back), A will lead B and when the encoder is rotating counterclockwise, A lags behind B. If the counter direction control logic is such that the counter counts upward when A leads B and counts downward when A lags B, then the counter gives direction control as well as distance from the reference.

Maximizing encoder accuracy

If there are 512 pulses on A, then the encoder position is accurate to within 360°/512.

You can get even greater accuracy by counting not only rising edges on A but also falling edges on A, giving position accuracy to 360 degrees/1024.

You get maximum accuracy counting rising and falling edges on A and on B (since B also has 512 pulses.) This gives a position accuracy of 360°/2048. These different modes are known as X1, X2, and X4.

Connecting the USB-2537 to an encoder

You can use up to two encoders with each USB-2537 in your acquisition system. Each A and B signal can be made as a single-ended connection with respect to common ground.

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USB-2537 User's Guide Functional Details

Differential applications are not supported.

For single-ended applications:

ƒ Connect signals A, B, and Z to the counter inputs on the USB-2537.

ƒ Connect each encoder ground to GND.

You can also connect external pull-up resistors to the USB-2537 counter input terminal blocks by placing a pull-up resistor between any input channel and the encoder power supply. Choose a pull-up resistor value based on the encoder's output drive capability and the input impedance of the USB-2537. Lower values of pull-up resistors cause less distortion, but also cause the encoder's output driver to pull down with more current.

Connecting external pull-up resistors to the USB-2537

For open-collector outputs, you can connect external pull-up resistors to the USB-2537's counter input terminal blocks. You can place a pull-up resistor between any input channel and the provided +5 V power supply.

Choose a pull-up resistor value based on the encoder's output drive capability and the input impedance of the

USB-2537. Lower values of pull-up resistors cause less distortion but also cause the encoder's output driver to pull down with more current.

Wiring to one encoder

: Figure 21 shows the connections for one encoder to a module.

The following figure illustrates connections for one encoder to a 68-pin SCSI connector on a USB-2537.

The "A" signal must be connected to an even-numbered channel and the associated "B" signal must be connected to the next [higher] odd-numbered channel. For example, if "A" were connected to CTR0, "B" would be connected to CTR1.

+5 VDC, pin 19

To ground (of external power source

Ground (to Digital Common pin 35, 36, 40)

Counter 0 (CNT0, pin 5) – To Encoder “A”

Counter 1 (CNT1, pin 39) – To Encoder “B”

Counter 2 (CNT2, pin 4) – To Encoder “Z”

Figure 21. Encoder connections to pins on the SCSI connector*

* Connections can instead be made to the associated screw-terminals of a connected TB-100 terminal connector option.

The "A" signal must be connected to an even-numbered channel and the associated "B" signal must be connected to the next higher odd-numbered channel. For example, if "A" were connected to counter 0, then "B" would be connected to counter 1.

If the encoder stops rotating, but is vibrating (due to it being mounted to a machine), you can use the debounce feature to eliminate false edges. Choose an appropriate debounce time and apply it to each encoder channel.

Refer to the Debounce modes section in the Functional Details chapter in this manual for additional information regarding debounce times.

You can get the relative position and velocity from the encoder. However, during an acquisition, you cannot get data that is relative to the Z-position until the encoder locates the Z-reference.

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USB-2537 User's Guide Functional Details

Note that the number of Z-reference crossings can be tabulated. If the encoder was turning in only one direction, then the Z-reference crossings equal the number of complete revolutions. This means that the data streaming to the PC is relative position, period = 1/velocity, and revolutions.

A typical acquisition might take six readings off of the USB-2537 as illustrated below. The user determines the scan rate and the number of scans to take.

Figure 22. USB-2537 acquisition of six readings per scan

Digital channels do not take up analog channel scan time.

In general, the output of each channel’s counter is latched at the beginning of each scan period (called the start-

of-scan.) Every time the USB-2537 receives a start-of-scan signal, the counter values are latched and are available to the USB-2537.

The USB-2537 clears all counter channels at the beginning of the acquisition. This means that the values returned during scan period 1 are always zero. The values returned during scan period 2 reflect what happened during scan period 1.

The scan period defines the timing resolution for the USB-2537. If you need a higher timing resolution, shorten the scan period.

Wiring for two encoders:

Figure 23 shows the single-ended connections for two encoders. Differential

connections do not apply.

+5 VDC, pin 19

Ground (to Digital Common)

Pin 35, 36, or 40

Counter 0 (CNT0), pin 5 –

To Encoder #1 “A”

Counter 1 (CNT1), pin 39 –

To Encoder #1 “B”

Counter 2 (CNT2), pin 4 –

To Encoder #2 “A”

Counter 3 (CNT3), pin 38 –

To Encoder #2 “B”

Encoder #1 Encoder #2

Figure 23. Two encoders connected to pins on the SCSI connector*

* Connections can instead be made to the associated screw-terminals of a connected TB-100 terminal connector option.

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USB-2537 User's Guide Functional Details

Each signal (A, B) can be connected as a single-ended connection with respect to the common digital ground

(GND). Both encoders can draw their power from the +5 V power output (pin 19) on the 68-pin SCSI connector.

Connect each encoder’s power input to +5 V power. Connect the return to digital common (GND) on the same connector. Make sure that the current output spec is not violated.

With the encoders connected in this manner, there is no relative positioning information available on encoder #1 or #2 since there is no Z signal connection for either. Therefore only distance traveled and velocity can be measured for each encoder.

Timer outputs

Two 16-bit timer outputs are built into the USB-2537. Each timer is capable of generating a different square wave with a programmable frequency in the range of 16 Hz to 1 MHz.

Figure 24. Typical USB-2537 timer channel

Example: Timer outputs

Timer outputs are programmable square waves. The period of the square wave can be as short as 1 µs or as long as 65535 µs. Refer to the table below for examples of timer output frequencies.

Divisor

Timer output frequency examples

Timer output frequency

The two timer outputs can generate different square waves. The timer outputs can be updated asynchronously at any time.

Using detection setpoints for output control

What are detection setpoints?

With the USB-2537's setpoint configuration feature, you can configure up to 16 detection setpoints associated with channels in a scan group. Each setpoint can update the following, allowing for real-time control based on acquisition data:

ƒ FIRSTPORTC digital output port with a data byte and mask byte

ƒ analog outputs (DACs)

ƒ timers

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USB-2537 User's Guide Functional Details

Setpoint configuration overview

You can program each detection setpoint as one of the following:

ƒ Single point referenced – Above, below, or equal to the defined setpoint.

ƒ Window (dual point) referenced – Inside or outside the window.

ƒ Window (dual point) referenced, hysteresis mode – Outside the window high forces one output (designated

Output 2; outside the window low-forces another output, designated as Output 1).

A digital detect signal is used to indicate when a signal condition is True or False—for example, whether or not the signal has met the defined criteria. The detect signals can be part of the scan group and can be measured as any other input channel, thus allowing real time data analysis during an acquisition.

The detection module looks at the 16-bit data being returned on a channel and generates another signal for each channel with a setpoint applied (Detect1 for Channel 1, Detect2 for Channel 2, and so on). These signals serve as data markers for each channel's data. It does not matter whether that data is volts, counts, or timing.

A channel's detect signal shows a rising edge and is True (1) when the channel's data meets the setpoint criteria.

The detect signal shows a falling edge and is False (0) when the channel's data does not meet the setpoint

criteria. The True and False states for each setpoint criteria are explained in the " Using the setpoint status register " section on page 45.

Criteria – input signal is equal to X

Compare X to:

Limit A or Limit B

Window* (nonhysteresis mode)

Window*

(hysteresis mode)

Setpoint definition (choose one)

ƒ

ƒ

ƒ

ƒ

ƒ

ƒ

ƒ

Equal to A (X = A)

Below A (X < A)

Above B (X > B)

Inside (B < X < A)

Outside: B > X; or, X > A

Above A (X > A)

Below (B X < B) (Both

conditions are checked when

in hysteresis mode

Action - driven by condition

Update conditions:

True only:

ƒ If True, then output value 1

ƒ If False, then perform no action

True and False:

ƒ If True, then output value 1

ƒ If False, then output value 2

True only

ƒ If True, then output value 1

ƒ If False, then perform no action

True and False

ƒ If True, then output value 1

ƒ If False, then output value 2

Hysteresis mode (forced update)

ƒ If X > A is True, then output value 2 until X < B is True, then output value 1.

ƒ If X < B is True, then output value 1 until X > A is True, then output value 2.

This is saying:

(a) If the input signal is outside the window high, then output value 2 until the signal goes outside the window low, and

(b) if the signal is outside the window low, then output value 1 until the signal goes outside the window high. There is no change to the detect signal while within the window.

The detect signal has the timing resolution of the scan period as seen in the diagram below. The detect signal can change no faster than the scan frequency (1/scan period.)

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USB-2537 User's Guide Functional Details

Figure 25. Example diagram of detection signals for channels 1, 2, and 3

Each channel in the scan group can have one detection setpoint. There can be no more than 16 total setpoints total applied to channels within a scan group.

Detection setpoints act on 16-bit data only. Since the USB-2537 has 32-bit counters, data is returned 16-bits at a time. The lower word, the higher word, or both lower and higher words can be part of the scan group. Each counter input channel can have one detection setpoint for the counter's lower 16-bit value and one detection setpoint for the counter's higher 16-bit value.

Setpoint configuration

You program all setpoints as part of the pre-acquisition setup, similar to setting up an external trigger. Since each setpoint acts on 16-bit data, each has two 16-bit compare values: a high limit (limit A) and a low limit

(limit B). These limits define the setpoint window.

There are several possible conditions (criteria) and effectively three update modes, as explained in the following configuration summary.

Set high limit

You can set the 16-bit high limit (limit A) when configuring the USB-2537 through software.

Set low limit

You can set the 16-bit low limit (limit B) when configuring the USB-2537 through software.

Set criteria

ƒ Inside window: Signal is below 16-bit high limit and above 16-bit low limit.

ƒ Outside window: Signal is above 16-bit high limit, or below 16-bit low limit.

ƒ Greater than value: Signal is above 16-bit low limit, so 16-bit high limit is not used.

ƒ

Less than value: Signal is below 16-bit high limit, so 16-bit low limit is not used.

ƒ Equal to value: Signal is equal to 16-bit high limit, and limit B is not used.

The equal to mode is intended for use when the counter or digital input channels are the source channel.

You should only use the equal to16-bit high limit (limit A) mode with counter or digital input channels as the channel source. If you want similar functionality for analog channels, then use the inside window mode

ƒ Hysteresis mode: Outside the window, high forces output 2 until an outside the window low condition exists, then output 1 is forced. Output 1 continues until an outside the window high condition exists. The cycle repeats as long as the acquisition is running in hysteresis mode.

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USB-2537 User's Guide Functional Details

Set output channel

ƒ

None

ƒ Update FIRSTPORTC

ƒ Update DAC

ƒ Update timerx

Update modes

ƒ Update on True only

ƒ Update on True and False

Set values for output

ƒ

16-bit DAC value, FIRSTPORTC* value, or timer value when input meets criteria.

ƒ 16-bit DAC value, FIRSTPORTC* value, or timer value when does not meet criteria.

* By default, FIRSTPORTC comes up as a digital input. You may want to initialize FIRSTPORTC to a known state before running the input scan to detect the setpoints.

When using setpoints with triggers other than immediate, hardware analog, or TLL, the setpoint criteria evaluation begins immediately upon arming the acquisition.

Using the setpoint status register

You can use the setpoint status register to check the current state of the 16 possible setpoints. In the register,

Setpoint 0 is the least-significant bit and Setpoint 15 is the most-significant bit. Each setpoint is assigned a value of 0 or 1.

ƒ A value of 0 indicates that the setpoint criteria is not met—in other words, the condition is False.

ƒ A value of 1 indicates that the criteria has been met—in other words, the condition is True.

In the following example, the criteria for setpoints 0, 1, and 4 is satisfied (True), but the criteria for the other 13 setpoints has not been met.

True (1)

False (0)

0 0 0 0 0 0 0 0 0 0 0 1 0 0 1 1

<<< Most significant bit Least significant bit >>>

From the above table we have

10011

binary, or 19 decimal, derived as follows:

ƒ Setpoint 0, having a True state, shows 1, giving us decimal 1.

ƒ Setpoint 1, having a True state, shows 1, giving us decimal 2.

ƒ

Setpoint 4, having a True state, shows 1, giving us decimal 16.

For proper operation, the setpoint status register must be the last channel in the scan list.

Examples of control outputs

Detecting on analog input, DAC, and FIRSTPORTC updates

Update mode: Update on True and False

Criteria: Channel 5 example: below limit; channel 4 example: inside window

In this example, channel 5 is programmed with reference to one setpoint (limit A), defining a low limit.

Channel 4 is programmed with reference to two setpoints (limit A and limit B) which define a window for that channel.

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USB-2537 User's Guide Functional Details

Channel Condition

5 Below limit A (for channel 5)

State of detect signal

True

False

limit A and limit B) for channel 4

False

Action

When channel 5 analog input voltage is below the limit

A, update DAC1 with output value 0.0 V.

When the above stated condition is false, update DAC1 with the Output Value of minus 1.0 V.

When Channel 4's analog input voltage is within the window, update FIRSTPORTC with 70h.

When the above stated condition is False (channel 4 analog input voltage is outside the window), update

FIRSTPORTC with 30h.

Figure 26. Analog inputs with setpoints update on True and False

In the channel 5 example, the setpoint placed on analog Channel 5 updated DAC1 with 0.0 V. The update occurred when channel 5's input was less than the setpoint (limit A). When the value of channel 5's input was above setpoint limit A, the condition of <A was false and DAC1 was then updated with minus1.0V.

You can program control outputs programmed on each setpoint, and use the detection for channel 4 to update the FIRSTPORTC digital output port with one value (70 h in the example) when the analog input voltage is within the shaded region and a different value when the analog input voltage is outside the shaded region (30 h in the example).

Detection on an analog input, timer output updates

Update Mode: Update on True and False

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USB-2537 User's Guide Functional Details

Criteria Used: Inside window

The figure below shows how a setpoint can be used to update a timer output. Channel 3 is an analog input channel. A setpoint is applied using update on True and False, with a criteria of inside-the-window, where the signal value is inside the window when simultaneously less than Limit A but greater than Limit B.

Whenever the channel 3 analog input voltage is inside the setpoint window (condition True), Timer0 is updated with one value; and whenever the channel 3 analog input voltage is outside the setpoint window (condition

False) timer0 will be updated with a second output value.

Figure 27. Timer output update on True and False

Using the hysteresis function

Update mode: N/A, the hysteresis option has a forced update built into the function

Criteria used: Window criteria for above and below the set limits

The figure below shows analog input Channel 3 with a setpoint which defines two 16-bit limits, Limit A (High) and Limit B (Low). These are being applied in the hysteresis mode and DAC channel 0 is updated accordingly.

In this example, Channel 3's analog input voltage is being used to update DAC0 as follows:

ƒ When outside the window, low (below limit B) DAC0 is updated with 3.0 V. This update remains in effect until the analog input voltage goes above Limit A.

ƒ When outside the window, high (above limit A), DAC0 is updated with 7.0 V. This update remains in effect until the analog input signal falls below limit B. At that time we are again outside the limit "low" and the update process repeats itself.

Hysteresis mode can also be done with FIRSTPORTC digital output port, or a timer output, instead of a DAC.

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Figure 28. Channel 3 in hysteresis mode

Using multiple inputs to control one DAC output

Update mode: Rising edge, for each of two channels

Criteria used: Inside window, for each of two channels

The figure below shows how multiple inputs can update one output. In the following figure, the DAC2 analog output is being updated. Analog input Channel 3 has an inside-the-window setpoint applied. Whenever Channel

3's input goes inside the programmed window, DAC2 will be updated with 3.0V.

Analog input Channel 7 also has an inside-the-window setpoint applied. Whenever channel 7's input goes inside the programmed window, DAC2 is updated with - 7.0V.

Figure 29. Using two criteria to control an output*

The update on True only mode was selected, and therefore the updates for DAC2 only occur when the criteria is met. However, in the above figure we see that there are two setpoints acting on one DAC. We can also see that the two criteria can be met simultaneously. When both criteria are True at the same time, the DAC2 voltage is associated with the criteria that has been most recently met.

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USB-2537 User's Guide Functional Details

Detecting setpoints on a totalizing counter

In the following figure, Channel 1 is a counter in totalize mode. Two setpoints define a point of change for

Detect 1 as the counter counts upward. The detect output is high when inside the window (greater than Limit B

(the low limit) but less than Limit A (the high limit).

In this case, the Channel 1 setpoint is defined for the 16 lower bits of channel 1's 32-bit value. The

FIRSTPORTC digital output port could be updated on a True condition (the rising edge of the detection signal).

You can also update one of the DAC output channels or timer outputs with a value.

At this point you can update FIRSTPORTC or DACs

Figure 30. Channel 1 in totalizing counter mode, inside the window setpoint

Detection setpoint details

Controlling analog, digital, and timer outputs

You can program each setpoint with an 8-bit digital output byte and corresponding 8-bit mask byte. When the setpoint criteria is met, the FIRSTPORTC digital output port can be updated with the given byte and mask. You can also program each setpoint with:

ƒ a 16-bit DAC update value, and any one of the four DAC outputs can be updated in real time

ƒ

a timer update value

In hysteresis mode, each setpoint has two forced update values. Each update value can drive one DAC, one timer, or the FIRSTPORTC digital output port. In hysteresis mode, the outputs do not change when the input

values are inside the window. There is one update value that gets applied when the input values are less than the window and a different update value that gets applied when the input values are greater than the window.

Update on True and False uses two update values. The update values can drive DACs, FIRSTPORTC, or timer outputs.

FIRSTPORTC digital outputs can be updated immediately upon setpoint detection. This is not the case for analog outputs, as these incur another 3 µs delay. This is due to the shifting of the digital data out to the D/A converter which takes 1 µs, plus the actual conversion time of the D/A converter, i.e., another 2µs (worst case).

Going back to the above example, if the setpoint for analog input Channel 2 required a DAC update it would occur 5µs after the ADC conversion for Channel 2, or 6µs after the start of the scan.

When using setpoints to control any of the DAC outputs, increased latencies may occur if attempting to stream data to DACs or pattern digital output at the same time. The increased latency can be as long as the period of

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USB-2537 User's Guide Functional Details

the DAC pacer clock. For these reasons, avoid streaming outputs on any DAC or pattern digital output when using setpoints to control DACs.

FIRSTPORTC, DAC, or timer update latency

Setpoints allow analog outputs, DACs, timers, or FIRSTPORTC digital outputs to update very quickly. Exactly how fast an output can update is determined by these factors:

ƒ

scan rate

ƒ synchronous sampling mode

ƒ type of output to be updated

For example, you set an acquisition to have a scan rate of 100 kHz, which means each scan period is 10 µs.

Within the scan period you sample six analog input channels. These are shown in the following figure as channels 1 through 6. The ADC conversion occurs at the beginning of each channel's 1 µs time block.

FIRSTPORTC

Figure 31. Example of FIRSTPORTC or DAC latency

By applying a setpoint on analog input channel 2, that setpoint gets evaluated every 10 µs with respect to the sampled data for channel 2.

Due to the pipelined architecture of the analog-to-digital converter system, the setpoint cannot be evaluated until 2 µs after the ADC conversion. In the example above, the FIRSTPORTC digital output port can be updated no sooner than 2 µs after channel 2 has been sampled, or 3 µs after the start of the scan. This 2 µs delay is due to the pipelined ADC architecture. The setpoint is evaluated 2 µs after the ADC conversion and then

FIRSTPORTC can be updated immediately.

The detection circuit works on data that is put into the acquisition stream at the scan rate. This data is acquired according to the pre-acquisition setup (scan group, scan period, etc.) and returned to the PC. Counters are latched into the acquisition stream at the beginning of every scan. The actual counters may be counting much faster than the scan rate, and therefore only every 10 th

, 100 th

, or n th

count shows up in the acquisition data.

As a result, you can set a small detection window on a totalizing counter channel and have the detection setpoint

"stepped over" since the scan period was too long. Even though the counter value stepped into and out of the detection window, the actual values going back to the PC may not. This is true no matter what mode the counter channel is in.

When setting a detection window, keep a scan period in mind. This applies to analog inputs and counter inputs.

Quickly changing analog input voltages can step over a setpoint window if not sampled often enough.

There are three possible solutions for overcoming this problem:

ƒ Shorten the scan period to give more timing resolution on the counter values or analog values.

ƒ Widen the setpoint window by increasing limit A and/or lowering limit B.

ƒ A combination of both solutions (1 and 2) could be made.

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Chapter 4

Calibrating the USB-2537

Every range of a USB-2537 device is calibrated at the factory using a digital NIST traceable calibration method.

This method works by storing a correction factor for each range on the unit at the time of calibration. For analog inputs, the user can adjust the calibration of the board while it is installed in the acquisition system. This does not destroy the factory calibration supplied with the board. This is accomplished by having two distinct calibration tables in the USB-2537 on-board EPROM—one which contains the factory calibration, and the other which is available for field calibration.

You can perform field calibration automatically in seconds with InstaCal and without the use of external hardware or instruments.

Field calibration derives its traceability through an on-board reference which has a stability of 0.005% per year.

Note that a two-year calibration period is recommended for USB-2537 boards.

You should calibrate the USB-2537 using InstaCal after the board has fully warmed up. The recommended warm-up time is 30 minutes. For best results, calibrate the board immediately before making critical measurements. The high resolution analog components on the board are somewhat sensitive to temperature.

Pre-measurement calibration ensures that your board is operating at optimum calibration values.

51

Chapter 5

Specifications

Typical for 25 °C unless otherwise specified.

Specifications in italic text are guaranteed by design.

Analog input

A/D converter type

Table 1. Analog input specifications

Successive approximation

Number of channels

Input ranges (SW programmable)

Maximum sample rate

Nonlinearity (integral)

Nonlinearity (differential)

A/D pacing

Trigger sources and modes

Acquisition data buffer

Configuration memory

Maximum usable input voltage

+ common mode voltage (CMV +

V in

)

Signal to noise and distortion

Total harmonic distortion

Calibration

CMRR @ 60 Hz

Bias current

Crosstalk

Input impedance

Absolute maximum input voltage

Accuracy

64 single-ended/32 differential, software-selectable

Bipolar: ±10 V, ±5 V, ±2 V, ±1 V , ±0.5 V, ±0.2 V, ±0.1 V

1 MHz

±2 LSB maximum

±1 LSB maximum

Onboard input scan clock, external source (XAPCR)

See Table 8

1 MSample

Programmable I/O

Range: ±10 V, ±5 V, ±2 V, ±1 V ,

±0.5 V

Range: ±0.2 V, ±0.1 V

10.5 V maximum

2.1 V maximum

72 dB typical for ±10 V range, 1 kHz fundamental

-80 dB typical for ±10 V range, 1 kHz fundamental

Auto-calibration, calibration factors for each range stored onboard in non-volatile

RAM.

-70 dB typical DC to 1 kHz

40 pA typical (0 °C to 35°C)

-75 dB typical DC to 60Hz; -65 dB typical @ 10kHz

10 MΩ single-ended, 20 MΩ differential

±30 V

Table 2. Analog input accuracy specifications

Voltage range

-10 V to 10 V

-5 V to 5 V

-2 V to 2 V

-1 V to 1 V

-500 mV to 500 mV

-200 mV to 200 mV

-100 mV to 100 mV

Note 1

Accuracy

±(% of reading + % range)

23°C ±10 °C, 1 year

0.031% + 0.008%

0.031% + 0.009%

0.031% + 0.010%

0.031% + 0.02%

0.031% + 0.04%

0.036% + 0.075%

0.042% + 0.15%

Temperature coefficient

±(ppm of reading + ppm range)/°C

14 + 8

14 + 9

14 +10

14 + 12

14 +18

14 +12

14 +18

Noise (cts

RMS)

2.0

3.0

2.0

3.5

5.5

8.0

14.0

Note 1:

Specifications assume differential input single-channel scan, 1 MHz scan rate, unfiltered,

CMV=0.0 V, 30 minute warm-up, exclusive of noise, range is +FS to -FS.

Note 2

52

USB-2537 User's Guide Specifications

Note 2:

Noise reflects 10,000 samples at 1 MHz, typical, differential short.

Thermocouples

Table 3. TC types and accuracy (Note 3)

TC type

J

K

T

E

R

S

N

B

Temperature range (°C)

-200 to + 760

-200 to + 1200

-200 to + 400

-270 to + 650

-50 to + 1768

-50 to + 1768

-270 to + 1300

+300 to + 1400

Accuracy (±°C) Noise typical (±°C)

1.7

1.8

1.8

1.7

4.8

4.7

2.7

3.0

0.2

0.2

0.2

0.2

1.5

1.5

0.3

1.0

Note 3:

Assumes 16384 oversampling applied, CMV = 0.0V, 60 minute warm-up, still environment, and

25 °C ambient temperature; excludes thermocouple error; TC in

= 0 °C for all types except B

(1000 °C), PS-9V1AEPS-2500 power supply for external power.

Analog outputs

Analog output channels can be updated synchronously relative to scanned inputs, and clocked from either an internal onboard clock, or an external clock source. Analog outputs can also be updated asynchronously, independent of any other scanning system.

Table 4. Analog output specifications

Channels 4

Resolution 16-bits

Data buffer

Output voltage range

Output current

Offset error

Digital feed-through

PC-based memory

±10 V

±1 mA; sourcing more current (1 to 10 mA) may require a PS-9V1AEPS-2500 power supply option

±0.0045 V maximum

<10 mV when updated

DAC analog glitch

Gain error

<12 mV typical at major carry

±0.01%

Coupling DC

Update rate 1 MHz maximum, resolution 20.83 ns

Settling time

Pacer sources

Trigger sources

2 µs to rated accuracy

Four programmable sources:

ƒ Onboard output scan clock, independent of scanning input clock

ƒ

Onboard input scan clock

ƒ External output scan clock (XDPCR), independent of external input scan clock (XAPCR)

ƒ External input scan clock (XAPCR)

Start of input scan

53

USB-2537 User's Guide Specifications

Digital input/output

Number of I/O

Ports

Input scanning modes

Input characteristics

Logic keeper circuit

Input protection

Input high

Input low

Output high

Output low

Output current

Digital input pacing

Digital output pacing

Digital input trigger sources and modes

Digital output trigger sources

Sampling/update rate

Pattern generation output

Table 5. Digital input/output specifications

24

Three banks of eight.

Each port is programmable as input or output

Two programmable

ƒ Asynchronous, under program control at any time relative to input scanning

ƒ Synchronous with input scanning

220 Ω series resistors, 20 pF to common

Holds the logic value to 0 or 1 when there is no external driver

±15 kV ESD clamp diodes parallel

+2.0 V to +5.0 V

0 to 0.8 V

>2.0 V

<0.8 V

Output 1.0 mA per pin, sourcing more current may require a PS-9V1AEPS-2500 power supply option

Onboard clock, external input scan clock (XAPCR)

Four programmable sources:

ƒ Onboard output scan clock, independent of input scan clock

ƒ Onboard input scan clock

ƒ External output scan clock (XDPCR), independent of external input scan clock

(XAPCR)

ƒ

External input scan clock (XAPCR)

See Table 8

Start of input scan

4 MHz maximum (rates up to 12 MHz are sustainable on some platforms)

Two of the 8-bit ports can be configured for 16-bit pattern generation. The pattern can also be updated synchronously with an acquisition at up to 4 MHz.

Counters

Counter inputs can be scanned based on an internal programmable timer or an external clock source.

Table 6. Counter specifications

Resolution 32-bit

Input frequency

Input signal range

Input characteristics

Trigger level

Minimum pulse width

De-bounce times

Time-base accuracy

Counter read pacer

Trigger sources and modes

20 MHz maximum

-5 V to 10 V

10 k

Ω pull-up, ±15 kV ESD protection

TTL

25 ns high, 25 ns low

16 selections from 500 ns to 25.5 ms, positive or negative edge sensitive, glitch detect mode or de-bounce mode

50 ppm (0 ° to 50 °C)

Onboard input scan clock, external input scan clock (XAPCR)

See Table 8

Programmable mode

Counter mode options

Counter

Totalize, clear on read, rollover, stop at all Fs, 16-bit or 32-bit, any other channel can gate the counter

54

USB-2537 User's Guide Specifications

Input sequencer

Analog, digital, and counter inputs can be scanned based on either an internal programmable timer or an external clock source.

Table 7. Input sequencer specifications

Input scan clock sources: two (see Note 4) Internal:

ƒ Analog channels from 1 µs to 1 sec in 20.83 ns steps.

ƒ

Digital channels and counters from 250 ns to 1 sec in 20.83 ns steps.

External. TTL level input (XAPCR):

ƒ Analog channels down to 1 µs minimum

ƒ Digital channels and counters down to 250 ns minimum

Programmable parameters per scan: Programmable channels (random order), programmable gain

Onboard channel to channel scan rate

External input scan clock (XAPCR) maximum rate

Clock signal range:

Analog: 1 MHz maximum

Digital: 4 MHz if no analog channels are enabled, 1 MHz with analog channels enabled

Analog: 1MHz

Digital: 4 MHz if no analog channels are enabled, 1 MHz with analog channels enabled

Logical zero: 0 V to 0.8 V

Logical one: 2.4 V to 5.0 V

50 ns high, 50 ns low Minimum pulse width

Note 4:

The maximum scan clock rate is the inverse of the minimum scan period. The minimum scan period is equal to 1 µs times the number of analog channels. If a scan contains only digital channels, then the minimum scan period is 250 ns.

Some platforms can sustain scan rates up to 83.33 ns for digital-only scans.

55

USB-2537 User's Guide Specifications

Trigger sources and modes

Input scan trigger sources

Input scan triggering modes

Table 8. Trigger sources and modes

ƒ

Single channel analog hardware trigger

ƒ Single channel analog software trigger

ƒ

External-single channel digital trigger (TTL TRG input)

ƒ Digital Pattern Trigger

ƒ Counter/Totalizer Trigger

ƒ Single channel analog hardware trigger:

The first analog input channel in the scan is the analog trigger channel

Input signal range: -10 V to +10 V maximum

Trigger level: Programmable (12-bit resolution)

Latency: 350 ns typical

Accuracy: ±0.5% of reading, ±2 mV offset maximum

Noise: 2 mV RMS typical

ƒ Single channel analog software trigger:

The first analog input channel in the scan is the analog trigger channel

Input signal range: Anywhere within range of the trigger channel

Trigger level: Programmable (16-bit resolution)

Latency: One scan period (maximum)

ƒ External-single channel digital trigger (TTL trigger input):

Input signal range: -15 V to +15 V maximum

Trigger level: TTL level sensitive

Minimum pulse width: 50 ns high, 50 ns low

Latency: One scan period maximum

ƒ Digital Pattern Triggering

8-bit or 16-bit pattern triggering on any of the digital ports. Programmable for trigger on equal, not equal, above, or below a value. Individual bits can be masked for “don’t care” condition.

Latency: One scan period, maximum

ƒ Counter/Totalizer Triggering

Counter/totalizer inputs can trigger an acquisition. User can select to trigger on a frequency or on total counts that are equal, not equal, above, or below a value, or within/outside of a window rising/falling edge.

Latency: One scan period, maximum

Frequency/pulse generators

Channels

Output waveform

Output rate

High-level output voltage

Low-level output voltage

Table 9. Frequency/pulse generator specifications

2 x 16-bit

Square wave

1 MHz base rate divided by 1 to 65535 (programmable)

2.0 V minimum @ -1.0 mA, 2.9 V minimum @ -400 µA

0.4 V maximum @ 400 µA

Power consumption

Table 10. Power consumption specifications (Note 5)

Power consumption (per board) 3400 mW

56

USB-2537 User's Guide Specifications

External power

Table 11. External power specifications (Note 5)

Connector

Power range

Switchcraft # RAPC-712

6 to 16 VDC (used when USB port supplies insufficient power, or when an independent power supply is desired)

20 V for 10 seconds, maximum

Over-voltage

Note 5:

An optional power supply (MCC p/n PS-9V1AEPS-2500) is required if the USB port cannot supply adequate power. USB 2.0 ports are, by USB 2.0 standards, required to supply 2500 mW

(nominal at 5 V, 500 mA)

USB specifications

USB-device type

Device compatibility

Table 12. USB specifications

USB 2.0 high-speed mode (480 Mbps) if available (recommended), otherwise,

USB 1.1 full-speed mode (12 Mbps)

USB 2.0 (recommended) or USB 1.1

Environmental

Operating temperature range

Storage temperature range

Relative humidity

Mechanical

Table 13. Environmental specifications

-30 °C to +70 °C

-40 °C to +80 °C

0 to 95% non-condensing

Vibration

Dimensions

Weight

Table 14. Mechanical specifications

MIL STD 810E cat 1 and 10

152.4 mm (W) x 150.62 mm (D) (6.0” x 5.93”)

147 g (0.32 lbs)

Signal I/O connectors and pin out

Connector type

Temperature measurement connector

Table 15. Main connector specifications

Compatible cables (for the 68-pin SCSI connector)

Compatible cables (for the 40-pin header connectors)

Compatible accessory products (for the 68-pin SCSI connector)

Compatible accessory products (for the 40-pin header connectors)

68-pin standard "SCSI TYPE III" female connector (P5); four 40-pin headers (J5, J6, J7, J8), AMP# 2-103328-0

4-channel TC screw-terminal block (TB7); Phoenix # MPT

0.5/9-2.54

CA-68-3R — 68-pin ribbon cable; 3 feet.

CA-68-3S — 68-pin shielded round cable; 3 feet.

CA-68-6S — 68-pin shielded round cable; 6 feet.

C40FF-#

TB-100 termination board with screw terminals

RM-TB-100, 19-inch rack mount kit for TB-100

CIO-MINI40

57

USB-2537 User's Guide

68-pin SCSI connector pin outs

Table 16. 68-pin SCSI connector pin out (labeled P5 on the board) single-ended mode

Pin Function

68 ACH0

67 AGND

66 ACH9

65 ACH2

64 AGND

63 ACH11

62 SGND (low level sense - not for general use)

61 ACH12

60 ACH5

59 AGND

58 ACH14

57 ACH7

56 XDAC3

55 XDAC2

54 NEGREF (reserved for self-calibration)

53 GND

52 A1

51 A3

50 A5

49 A7

48 B1

47 B3

46 B5

45 B7

44 C1

43 C3

42 C5

41 C7

40 GND

39 CNT1

38 CNT3

37 TMR1

36 GND

35 GND

4

3

6

5

2

1

8

7

10

9

14

13

12

11

18

17

16

15

22

21

20

19

26

25

24

23

30

29

28

27

34

33

32

31

B0

B2

B4

B6

A0

A2

A4

A6

C0

C2

C4

C6

ACH8

ACH1

AGND

ACH10

ACH3

AGND

ACH4

AGND

ACH13

ACH6

AGND

ACH15

XDAC0

XDAC1

POSREF (reserved for self-calibration)

+5 V (see )

CNT0

CNT2

TMR0

XAPCR (input scan clock)

XDPCR (output scan clock)

Specifications

58

USB-2537 User's Guide Specifications

Table 17. 68-pin SCSI connector pin out (labeled P5 on the board) differential mode

Pin Function

68 ACH0 HI

67 AGND

65 ACH2 HI

64 AGND

62 SGND (not for general use)

60 ACH5 HI

59 AGND

57 ACH7 HI

56 XDAC3

55 XDAC2

54 NEGREF (reserved for self-calibration)

53 GND

52 A1

51 A3

50 A5

49 A7

48 B1

47 B3

46 B5

45 B7

44 C1

43 C3

42 C5

41 C7

40 GND

39 CNT1

38 CNT3

37 TMR1

36 GND

35 GND

14

13

12

11

18

17

16

15

8

7

10

9

22

21

20

19

26

25

24

23

30

29

28

27

34

33

32

31

4

3

6

5

2

1

ACH0 LO

AGND

ACH2 LO

AGND

ACH4 HI

AGND

ACH5 LO

B0

B2

B4

B6

A0

A2

A4

A6

C0

C2

C4

C6

AGND

ACH7 LO

XDAC0

XDAC1

POSREF (reserved for self-calibration)

+5 V (see )

CNT0

CNT2

TMR0

XAPCR (input scan clock)

XDPCR (output scan clock)

Note 6:

5 V output, ±20% tolerance, 2mA USB powered, 10mA using external power.

40-pin header connector pin outs

This edge of the header is closest to the center of the

USB-2537. Pins 2 and 40 are labeled on the board silkscreen.

59

USB-2537 User's Guide Specifications

J5

Table 18. 40-pin header connector pinout (labeled J5 on the board)

64-channel single-ended mode

Pin Function

1 ACH27

3 ACH26

5 AGND

7 ACH3

9 ACH2

11 ACH17

13 ACH16

15

17

ACH1

ACH0

19

21

23

25

27

29

AGND

ACH23

ACH22

ACH7

ACH6

AGND

31

33

ACH29

ACH28

35 ACH13

37 ACH12

39 AGND

Pin Function

2 ACH19

4 ACH18

6 AGND

10 ACH10

14

16

18

20

22

24

26

28

30

ACH24

ACH9

ACH8

AGND

ACH31

ACH30

ACH15

ACH14

ACH21

32

34

ACH20

ACH5

36 ACH4

38 AGND

40 AGND

Table 19. 40-pin header connector pinout (labeled J5 on the board)

32-channel differential mode

Pin Function

17

19

21

23

25

27

29

31

33

35

1

3

ACH11 LO

ACH10 LO

5 AGND

7

9

11

13

15

ACH3 HI

ACH2 HI

ACH9 HI

ACH8 HI

ACH1 HI

ACH0 HI

AGND

ACH15 HI

ACH14 HI

ACH7 HI

ACH6 HI

AGND

ACH13 LO

ACH12 LO

ACH5 LO

Pin

2

4

18

20

22

24

26

28

8

10

12

14

16

30

32

34

36

Function

ACH11 HI

ACH10 HI

ACH3 LO

ACH2 LO

ACH9 LO

ACH8 LO

ACH1 LO

ACH0 LO

AGND

ACH15 LO

ACH14 LO

ACH7 LO

ACH6 LO

ACH13 HI

ACH12 HI

ACH5 HI

ACH4 HI

39 AGND 40 AGND

60

USB-2537 User's Guide Specifications

J6

Pin Function

1 ACH43

3 ACH35

5 AGND

7 ACH42

9 ACH34

11 AGND

13 ACH41

15

17

ACH33

ACH40

19

21

23

25

27

29

ACH32

ACH47

ACH39

ACH46

ACH38

AGND

31

33

ACH45

ACH37

35 ACH44

37 ACH36

39 AGND

Pin Function

2 ACH59

4 ACH51

6 ACH58

10 ACH57

14

16

18

20

22

24

26

28

30

ACH56

ACH48

AGND

ACH63

ACH55

AGND

ACH62

ACH54

ACH61

32

34

ACH53

ACH60

36 ACH52

38 AGND

40 AGND

Table 21. 40-pin header connector pinout (labeled J6 on the board)

32-channel differential mode

Pin Function

17

19

21

23

25

27

29

31

33

35

1

3

ACH19 LO

ACH19 HI

5 AGND

7

9

11

13

15

ACH18 LO

ACH18 HI

AGND

ACH17 LO

ACH17 HI

ACH16 LO

ACH16 HI

ACH23 LO

ACH23 HI

ACH22 LO

ACH22 HI

AGND

ACH21 LO

ACH21 HI

ACH20 LO

39

Table 20. 40-pin header connector pinout (labeled J6 on the board)

64-channel single-ended mode

AGND

Pin

2

4

Function

ACH27 LO

ACH27 HI

18

20

22

24

26

28

8

10

12

14

16

ACH26 HI

ACH25 LO

ACH25 HI

ACH24 LO

ACH24 HI

AGND

ACH31 LO

ACH31 HI

AGND

ACH30 LO

ACH30 HI

30

32

34

36

ACH29 LO

ACH29 HI

ACH28 LO

ACH28 HI

38 AGND

40 AGND

61

USB-2537 User's Guide

J7

Pin Function

13

15

17

19

21

23

1 GND

3 A0

5 A1

7 A2

9 A3

11 GND

B0

B1

B2

B3

GND

C0

25

27

29

31

33

35

C1

C2

C3

GND

TMR0

CNT0

37 CNT2

39 GND

J8

Table 22. 40-pin header connector pin out (labeled J7 on the board)

Pin Function

2 XAPCR (input scan clock)

4 A4

6 A5

10 A7

26

28

30

32

34

36

14

16

18

20

22

24

B4

B5

B6

B7

+5 V (see

C4

C5

C6

C7

TMR1

CNT1

CNT3

Note 7 )

38 GND

40 GND

Table 23. 40-pin header connector pin out (labeled J8 on the board)

Pin Function

1 +13 V (see Note 8 )

3 NC

15

17

19

21

23

25

5 AGND

7 XDAC0

9 XDAC1

11 AGND

13 SelfCal

AGND

TTL TRG

XAPCR (input scan clock)

GND (digital)

NC

+5 V (see Note 7 )

27

29

31

33

NC

NC

NC

NC

35 NC

37 NC

39 NC

Pin Function

2 -13 V (see Note 8 )

4 NC

6 AGND

10 XDAC3

14

16

18

20

22

24

26

SGND (low level sense - not for general use)

AGND

XDPCR (output scan clock)

GND (digital)

GND (digital)

NC

AUX PWR (output - reserved)

28

30

32

34

NC

NC

NC

NC

36 NC

38 NC

40 NC

Note 7:

5 V output, ±20% tolerance, 2mA USB powered, 10mA using external power.

Note 8:

±13 V outputs, ±10% tolerance, 1 mA USB powered, 5 mA using external power

Specifications

62

USB-2537 User's Guide

TC connector pin out (TB7)

Standoff

Figure 32. TC terminal pin out (labeled TB7)

Specifications

63

Measurement Computing Corporation

10 Commerce Way

Suite 1008

Norton, Massachusetts 02766

(508) 946-5100

Fax: (508) 946-9500

E-mail: [email protected] www.mccdaq.com

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