Measurement Specialties USB-1616HS-2 User Manual

USB-1616HS-2

User's Guide

Document Revision 1, August, 2007

© Copyright 2007, Measurement Computing Corporation

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the protection of the most comprehensive warranties and unmatched phone tech support. It’s the embodiment of our mission:

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
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HM USB-1616HS-2.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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Computing Corporation.

Notice

Measurement Computing Corporation does not authorize any Measurement Computing Corporation product for use
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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-1616HS-2............................................................................................................8

Overview: USB-1616HS-2 features ...................................................................................................................8

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

Chapter 2

Installing the USB-1616HS-2................................................................................................................9

What comes with your USB-1616HS-2 shipment? ............................................................................................9

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

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

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

Unpacking the USB-1616HS-2 ........................................................................................................................10

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

Installing the hardware .....................................................................................................................................11

Configuring the hardware.................................................................................................................................12

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

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

Screw terminal pin outs ...................................................................................................................................................13

DSUB25F expansion connector.......................................................................................................................................14

Cabling.............................................................................................................................................................................15

Chapter 3

Functional Details ...............................................................................................................................16

USB-1616HS-2 components ............................................................................................................................16

USB-1616HS-2 block diagram.........................................................................................................................18

Synchronous I/O – mixing analog, digital, and counter scanning ....................................................................18

Analog input .....................................................................................................................................................19

Analog input scanning .....................................................................................................................................................19

Thermocouple input..........................................................................................................................................22

Tips for making accurate temperature measurements ......................................................................................................22

Analog output ...................................................................................................................................................23

Example: Analog channel scanning of voltage inputs and streaming analog outputs......................................................23

Digital I/O.........................................................................................................................................................24

Digital input scanning......................................................................................................................................................24

Digital outputs and pattern generation.............................................................................................................................24

Triggering.........................................................................................................................................................24

Hardware analog triggering .............................................................................................................................................25

Digital triggering..............................................................................................................................................................25

Software-based triggering................................................................................................................................................25

Stop trigger modes...........................................................................................................................................................26

Pre-triggering and post-triggering modes ........................................................................................................................26

Counter inputs ..................................................................................................................................................26

5

USB-1616HS-2 User's Guide

Tips for making high-speed counter measurements (> 1 MHz).......................................................................................27

Mapped channels .............................................................................................................................................................27

Counter modes.................................................................................................................................................................27

Debounce modes..............................................................................................................................................................28

Encoder mode ..................................................................................................................................................................31

Timer outputs....................................................................................................................................................34

Example: Timer outputs...................................................................................................................................................34

Using multiple USB-1616HS-2s per PC ..........................................................................................................35

Detection setpoint overview .............................................................................................................................35

Setpoint configuration......................................................................................................................................................37

Using the setpoint status register......................................................................................................................................37

Examples of control outputs ............................................................................................................................................38

Detection setpoint details.................................................................................................................................................42

FIRSTPORTC, DAC, or timer update latency.................................................................................................................42

Chapter 4

Calibrating the USB-1616HS-2...........................................................................................................44

Chapter 5

Specifications......................................................................................................................................45

Analog input .....................................................................................................................................................45

Accuracy..........................................................................................................................................................................45

Thermocouples ................................................................................................................................................................46

Analog outputs..................................................................................................................................................46

Digital input/output...........................................................................................................................................47

Counters............................................................................................................................................................48

Input sequencer.................................................................................................................................................48

Triggering.........................................................................................................................................................49

Frequency/pulse generators ..............................................................................................................................49

Power consumption ..........................................................................................................................................49

External power..................................................................................................................................................50

USB specifications ...........................................................................................................................................50

Environmental ..................................................................................................................................................50

Mechanical .......................................................................................................................................................50

Signal I/O connectors and pin out ....................................................................................................................50

Declaration of Conformity ..................................................................................................................53

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-1616HS-4 so that you get the most out of
its analog I/O, thermocouple (TC) input, digital I/O, 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.

<#:#> 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 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 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 USB­1616HS-2.

 MCC's Specifications: USB-1616HS-2 (the PDF version of the "Specifications" chapter in this guide) is

available on our web site at www.mccdaq.com/pdfs/USB-1616HS-2.pdf

 MCC's Quick Start Guide is available on our web site at

www.mccdaq.com/PDFmanuals/DAQ-Software-Quick-Start.pdf

 MCC's Guide to Signal Connections is available on our web site at

www.mccdaq.com/signals/signals.pdf

 MCC's Universal Library User's Guide is available on our web site at

www.mccdaq.com/PDFmanuals/sm-ul-user-guide.pdf

 MCC's Universal Library Function Reference is available on our web site at

www.mccdaq.com/PDFmanuals/sm-ul-functions.pdf

 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-1616HS-2 User's Guide (this document) is also available on our web site at

www.mccdaq.com/PDFmanuals/USB-1616HS-2.pdf

.

7

Chapter 1

Introducing the USB-1616HS-2

Overview: USB-1616HS-2 features

The USB-1616HS-2 is supported under popular Microsoft® Windows® operating systems. The USB-1616HS-2
board is a multifunction measurement and control board designed for the USB bus.

The USB-1616HS-2 provides either eight differential or 16 single-ended analog inputs with 16-bit resolution. 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 eight of the analog inputs as differential thermocouple (TC) inputs.

The USB-1616HS-2 has two 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

Six banks of removable screw-terminal blocks provide connectivity to the analog input channels, digital I/O
lines, counter/timer channels, and analog outputs.

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

1

.

Software features

For information on the features of InstaCal and the other software included with your USB-1616HS-2, 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-1616HS-2

What comes with your USB-1616HS-2 shipment?

As you unpack your USB-1616HS-2, verify that the following components are included.

Hardware

 USB-1616HS-2

Chapter 2

 USB cable (2-meter length)

TR-2U power supply and CA-1* line cord

AC-to-DC conversion power supply and cord plugs into the external power connector of the USB-1616HS-2.

* European customers: Contact Measurement Computing to order the CA-261 line cord for your region.

Optional components

Expansion devices and cables and that are compatible with the USB-1616HS-2 and must be ordered separately.

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

9

USB-1616HS-2 User's Guide Installing the USB-1616HS-2

AI-EXP48

Analog input expansion module adds up to 24 differential or 48 single-ended inputs to the USB-1616HS-2.

CA-96A expansion cable

Expansion cable for connecting to the AI-EXP48 expansion board.

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-1616HS-2 and information regarding installation of that software.
Please read this booklet completely before installing any software or hardware.

Unpacking the USB-1616HS-2

As with any electronic device, you should take care while handling to avoid damage from static
electricity. Before removing the USB-1616HS-2 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:

 Phone: [phone] and follow the instructions for reaching Tech Support.
 Fax: [phone] to the attention of Tech Support
 Email: [e-mail]

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-1616HS-2.

10

USB-1616HS-2 User's Guide Installing the USB-1616HS-2

Installing the hardware

To connect the USB-1616HS-2 to your system, turn your computer on, and then do the following:

 Connect signal lines to the USB-1616HS-2's removable screw terminal blocks.

o Connect voltage signals as single-ended or differential connections (see Figure 1).

o Connect thermocouple signals as differential connections (see Figure 1). The negative (typically, the

red) thermocouple wire connects to the channel's LO connector, and the other color wire connects to
the channel's HI connector.

Always use differential input mode for thermocouple connections.

Figure 1. Single-ended voltage connections (V

and V2) and differential thermocouple connections (V3)

1

 If you are using an AI-EXP48 expansion device, connect it to the USB-1616HS-2. Make sure you do not

connect the AI-EXP48 to a live USB-1616HS-2. If the USB cable is connected to the computer, unplug it
before you connect the AI-EXP48.

 If you are using the TR-2U external supply (sold separately), connect the power supply to the USB-

1616HS-2's external power connector, and plug the other end into a power outlet.

The TR-2U is optional, but can be used in any scenario. You may need a TR-2U

power supply if the USB

port does not provide enough power for your USB-1616HS-2 application.

The USB-1616HS-2 requires 3000 mW by itself, and 3400 mW when connected to the AI-EXP48.

By USB2 standards, USB 2.0 ports are required to provide at least 2500 mW.

 Connect the USB cable to the USB-1616HS-2 USB connector and to a USB port on your computer. A

USB2.0 port is recommended—connecting to a USB1.1 port results in lower performance.

When you connect the USB-1616HS-2 for the first time, a

Found New Hardware message opens as the

USB-1616HS-2 is detected. When the message closes, the installation is complete.

The

power LED (bottom LED) blinks during device detection and initialization, and then remains solid if

properly detected. If not, check if the USB-1616HS-2 has sufficient power. When the board is first powered on,
there is usually a momentary delay before the power LED begins to blink, or come on solid.

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

USB-1616HS-2, or you may lose data and/or your ability to communicate with the USB-1616HS-

2.

11

USB-1616HS-2 User's Guide Installing the USB-1616HS-2

Configuring the hardware

All hardware configuration options on the USB-1616HS-2 are software-controlled. You can select some of the
configuration options using InstaCal, such as the analog input configuration (16 single-ended or 8 differential
channels), and the edge used for pacing when using an external clock. When measuring from thermocouples,
make sure you configure the channels for differential mode.

Once selected, any program that uses the Universal Library initializes the hardware according to these
selections.

Caution! 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 terminals 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-1616HS-2 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-1616HS-2.

Main connector specifications

Main connectors Six banks of removable screw-terminal blocks

Expansion connector 25-pin DSUB, female (DSUB25F)

Compatible cable for the 25-pin expansion connector CA-96A

Compatible accessory product for the 25-pin expansion
connector

AI-EXP48 expansion board with screw terminals (can connect
to the USB-1616HS-2 directly, or with the CA-96A cable)

12

USB-1616HS-2 User's Guide Installing the USB-1616HS-2

Screw terminal pin outs

USB-1616HS-2 screw terminal pin out – single-ended connections

Analog common (Ad) Digital common (Dd)
Analog output 0 (AO0) FIRSTPORTA Bit 0 (A0)
Analog output 1 (AO1) FIRSTPORTA Bit 1 (A1)

NC FIRSTPORTA Bit 2 (A2)
NC FIRSTPORTA Bit 3 (A3)

Analog Out

Analog In

Analog In

CAL (Reserved for self-calibration) FIRSTPORTA Bit 5 (A5)

Analog common (Ad) FIRSTPORTA Bit 4 (A4)

Signal ground (Sd) FIRSTPORTA Bit 6 (A6)

Digital common (Dd) FIRSTPORTA Bit 7 (A7)

TTL trigger (TRG)

Output scan clock I/O (DPR) Timer 0 (T0)

Input scan clock I/O (APR) Timer 1 (T1)

Analog common (Ad) Digital common (Dd)

CH 0 (0H) FIRSTPORTB Bit 0 (B0)

CH 8 (8L) FIRSTPORTB Bit 1 (B1)

Analog common (Ad) FIRSTPORTB Bit 2 (B2)

CH 1 (1H) FIRSTPORTB Bit 3 (B3)

CH 9 (9L) FIRSTPORTB Bit 4 (B4)

Analog common (Ad) FIRSTPORTB Bit 5 (B5)

CH 2 (2H) FIRSTPORTB Bit 6 (B6)

CH 10 (10L) FIRSTPORTB Bit 7 (B7)

Analog common (Ad)

CH 3 (3H) Counter 0 (CT0)

CH 11 (11L) Counter 1 (CT1)

Analog common (Ad) Digital common (Dd)

CH 4 (4H) FIRSTPORTC Bit 0 (C0)

CH 12 (12L) FIRSTPORTC Bit 1 (C1)

Analog common (Ad) FIRSTPORTC Bit 2 (C2)

CH 5 (5H) FIRSTPORTC Bit 3 (C3)

CH 13 (13L) FIRSTPORTC Bit 4 (C4)

Analog common (Ad) FIRSTPORTC Bit 5 (C5)

CH 6 (6H) FIRSTPORTC Bit 6 (C6)

CH 14 (14L) FIRSTPORTC Bit 7 (C7)

Analog common (Ad)

CH 7 (7H) Counter 2 (CT2)

CH 15 (15L) Counter 3 (CT3)

Port A

Digital common (Dd)

Port B

Digital common (Dd)

Port C

Digital common (Dd)

DIG-Tmr I/O

Dig-Ctr I/O

Dig-Ctr I/O

13

USB-1616HS-2 User's Guide Installing the USB-1616HS-2

5

USB-1616HS-2 screw terminal pin out – differential connections

Analog common (Ab) Digital common (Db)

Analog output 0 (AO0) FIRSTPORTA Bit 0 (A0)
Analog output 1 (AO1) FIRSTPORTA Bit 1 (A1)

NC FIRSTPORTA Bit 2 (A2)
NC FIRSTPORTA Bit 3 (A3)

Analog Out

Analog In

Analog In

CAL (Reserved for self-calibration) FIRSTPORTA Bit 5 (A5)

Analog common (Ab) FIRSTPORTA Bit 4 (A4)

Signal ground (Sb) FIRSTPORTA Bit 6 (A6)

Digital common (Db) FIRSTPORTA Bit 7 (A7)

TTL trigger (TRG)

Output scan clock I/O (DPR)

Input scan clock I/O (APR)

Analog common (Ab) Digital common (Db)

CH 0 HI (0H) FIRSTPORTB Bit 0 (B0)

CH 0 LO (8L) FIRSTPORTB Bit 1 (B1)

Analog common (Ab) FIRSTPORTB Bit 2 (B2)

CH 1 HI (1H) FIRSTPORTB Bit 3 (B3)

CH 1 LO (9L) FIRSTPORTB Bit 4 (B4)

Analog common (Ab) FIRSTPORTB Bit 5 (B5)

CH 2 HI (2H) FIRSTPORTB Bit 6 (B6)

CH 2 LO (10L) FIRSTPORTB Bit 7 (B7)

Analog common (Ab)

CH 3 HI (3H) Counter 0 (CT0)

CH 3 LO (11L) Counter 1 (CT1)

Analog common (Ab) Digital common (Db)

CH 4 HI (4H) FIRSTPORTC Bit 0 (C0)

CH 4 LO (12L) FIRSTPORTC Bit 1 (C1)

Analog common (Ab) FIRSTPORTC Bit 2 (C2)

CH 5 HI (5H) FIRSTPORTC Bit 3 (C3)

CH 5 LO (13L) FIRSTPORTC Bit 4 (C4)

Analog common (Ab) FIRSTPORTC Bit 5 (C5)

CH 6 HI (6H) FIRSTPORTC Bit 6 (C6)

CH 6 LO (14L) FIRSTPORTC Bit 7 (C7)

Analog common (Ab)

CH 7 HI (7H) Counter 2 (CT2)

CH 7 LO (15L) Counter 3 (CT3)

Port A

Digital common (Db)
Timer 0 (T0)
Timer 1 (T1)

Port B

Digital common (Db)

Port C

Digital common (Db)

DIG-Tmr I/O

Dig-Ctr I/O

Dig-Ctr I/O

DSUB25F expansion connector

13

2

Figure 2. DSUB25 expansion connector pin out

14

14

1

USB-1616HS-2 User's Guide Installing the USB-1616HS-2

Cabling

Use a CA-96A 25-pin expansion cable (CA-96A expansion cable) to connect to the USB-1616HS-2's 25-pin
expansion connector.

Figure 3. CA-96A expansion cable

15

Functional Details

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

 a diagram and explanations of physical board components
 a functional block diagram
 information on how to use the signals generated by the board
 diagrams of signals using default or conventional board settings

USB-1616HS-2 components

These USB-1616HS-2 components are shown in Figure 4.

 Six removable screw terminal blocks
 One USB port
 One external power connector
 One 25-pin expansion connector
 Two LED indicators ("Active" and "Power")

Chapter 3

Analog output, calibration,
TTL trigger and pacer signal

Analog input, screw terminal
blocks

Analog input, screw terminal
blocks

Figure 4. USB-1616HS-2 components – front view

16

DSUB25 expansion
connector

USB-1616HS-2 User's Guide Functional Details

Device "Active"
LED

Counter and digital I/O (port C)
screw terminal blocks

External

Counter and digital I/O (port B)
screw terminal blocks

"Power" LED

USB connector

Timer and digital I/O (port A)
screw terminal blocks

External power connector

Figure 5. USB-1616HS-2 components – rear view

External power connector

Although the USB-1616HS-2 is powered by a USB port on a host PC, an external power connector may also be
required to provide sufficient power for the USB-1616HS-2.

Connect the optional TR-2U power supply to the external power supply connector. This power supply provides
9 VDC, 1 A power to the USB-1616HS-2.

17

USB-1616HS-2 User's Guide Functional Details

USB-1616HS-2 block diagram

Figure 6 shows a simplified block diagram of the USB-1616HS-2. This board provides all of the functional
elements shown in the figure.

2

8

8

DSUB25F

Expansion connector

D/A converters

16

2

2

2

2

24

16-bit

Analog channel
input protection

One TTL

trigger input

One analog

input pacer clock

Two 16-bit

Timer outputs

Four 32 -bit

counter inputs

Three 8-bit

DIO ports

1 MHz

output clock

8 diff/16 SE

analog inputs

MUX

A

A

System

controller

Configurable

Programmable gain

amplifier

x1, x2,
x5, x10, x20
x50, x100

512-step

random access

channel/gain

sequencer

Programmable

sequencer

timebase

µ

1 s to 6 hours

PLD

1 MHz

input clock

Sequencer reset

USB

controller

Configurable

EPROM

16-bit, 1 MHz

A/D converter

DC to DC
converter

A

1 MSample

FIFO

Data Buffer

USB port

External

power

Connect the optional

power supply

if the USB cannot

supply enough power.

Figure 6. USB-1616HS-2 functional block diagram

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

The USB-1616HS-2 can read analog, digital, and counter inputs, while generating up to two 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.

18

USB-1616HS-2 User's Guide Functional Details

Analog input

The USB-1616HS-2 has a 16-bit, 1-MHz A/D coupled with 16 single-ended, or eight differential analog inputs.
Seven software programmable ranges provide inputs from ±10 V to ±100 mV full scale.

Analog input scanning

The USB-1616HS-2 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 ADC settling time set to 1 µs, 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 time
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 7

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. 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 one divided by 6 µs, or 166,666 Hz.

Example: Analog channel scanning of voltage and temperature inputs

Figure 8

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

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

Figure 7. Analog channel scan of voltage inputs example

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

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.

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USB-1616HS-2 User's Guide Functional Details

If you want 256 oversamples, then each analog channel in the scan group will take 256 µs, and the returned 16­bit 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 8. 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, CJC2 with TC3, CJC3 with TC4, CJC4 with TC5
and TC6, and CJC5 with TC7.

When the AI-EXP48 module is connected to the USB-1616HS-2, associate CJC6 with TC8 through TC11,
CJC7 with TC12 through TC15, CJC8 with TC16 through TC19, CJC9 with TC20 through TC23, CJC10 with
TC24 through TC27, and CJC11 with TC28 through TC31.

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.

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 9. Analog and digital scanning, once per scan mode example

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USB-1616HS-2 User's Guide Functional Details

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-1616HS-2 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.

Figure 10. 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-1616HS-2 has an onboard 1 MS buffer for acquired data.

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USB-1616HS-2 User's Guide Functional Details

Thermocouple input

You can configure up to eight analog inputs in differential mode on the USB-1616HS-2 to accept a
thermocouple (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 eight thermocouple channels.

When measuring TCs, the USB-1616HS-2 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-1616HS-2 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.

The USB-1616HS-2 does not have open thermocouple detection.

Tips for making accurate temperature measurements

 Set the rejection frequency to equal the line frequency.
 Warm up the USB-1616HS-2 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.

 Make sure the surrounding environment is thermally stabilized and ideally around 20 °C to 30 °C. If the

device'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.

 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.

 Use shielded TC wire (see "Shielding

The USB-1616HS-2 has several analog commons on the screw terminals.

You can also minimize the effect of noise by averaging readings (see "Averaging
both shielding and averaging.

" below) with the shield connected to analog common to reduce noise.

" below), or combining

Refer to "Screw terminal pin outs
screw terminals.

 Make sure the USB-1616HS-2 is mounted on a flat surface.
 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 reduce noise.

The USB-1616HS-2 several analog common screw terminals (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.

" section starting on page 13 for the locations of these analog common

"

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USB-1616HS-2 User's Guide Functional Details

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

 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.

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

signals.

Analog output

The USB-1616HS-2 has two 16-bit, 1 MHz analog output channels. Analog outputs can be updated at a
maximum rate of 1 MHz.

The channels have an output range of -10 V to +10 V. Each D/A can continuously output a waveform. In
addition, a program can asynchronously output a value to any of the D/A channels for non-waveform
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.



Internal output scan clock: The onboard programmable clock can generate updates ranging from 1 Hz to

1 MHz.



External output scan clock: A user-supplied external output scan clock at the DPR screw terminal.

 External input scan clock: A user-supplied external input scan clock at APR can pace both the D/A and

the analog input.



Internal input scan clock: The internal ADC scan clock.

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

The example shown in Figure 11 adds two DACs and a 16-bit digital pattern output to the example presented in
Figure 7 on page 19.

Figure 11. 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
output scan clock. All DACs and the 16-bits of pattern digital output are updated at the beginning of each scan.

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USB-1616HS-2 User's Guide Functional Details

Due to the time it takes to shift the digital data out to the DACs, plus the actual settling time of the digital-to­analog 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-1616HS-2.

You can 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.

You can also synchronize everything—input scans, DACs, pattern digital outputs—to one clock, which is either
internally-generated or externally-applied.

Digital I/O

Twenty-four TTL-level digital I/O lines are included in each USB-1616HS-2. 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
You can access input ports asynchronously from the PC at any time, including when a scanned acquisition is
occurring.

Digital input scanning

" below).

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 13 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.

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-1616HS-2 supports digital pattern
generation with bus mastering DMA. 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 onboard 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-1616HS-2 supports the
following trigger modes to accommodate certain measurement situations.

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USB-1616HS-2 User's Guide Functional Details

Hardware analog triggering

The USB-1616HS-2 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 to trigger on, 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:

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

 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.

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

(± some tolerance) the sweep will be triggered.

 Before re-arming the trigger, again 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, 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 (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.

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 as the trigger channel. You can program the trigger level, the rising or falling
edge to trigger on, 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.

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USB-1616HS-2 User's Guide Functional Details

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-1616HS-2 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-1616HS-2 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.

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-1616HS-2 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.

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-1616HS-2. Each counter accepts frequency inputs up to 20 MHz.

USB-1616HS-2 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.

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USB-1616HS-2 User's Guide Functional Details

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 counter mode explanations below.

Figure 12. Typical USB-1616HS-2 counter channel

Tips for making high-speed counter measurements (> 1 MHz)

 Use coax or twisted-pair wire. Connect one side to Digital Common.
 If the frequency source is tolerant, parallel-terminate the coax or twisted-pair with a 50  or 100  resistor

at the terminal block.

 The amplitude of the driving waveform should be as high as possible without violating the over-voltage

specification.

 To ensure adequate switching, waveforms should swing at least 0 V to 5 V and have a high slew rate.

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:

 gate the counter
 decrement the counter
 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 mapped channel to latch the counter output.

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.

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USB-1616HS-2 User's Guide Functional Details

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-1616HS-2.

Clear on read mode is only available if the counter is in asynchronous mode the. The counter's lower 16-bit
value should be read first. This will latch the full 32-bit result and clear the counter. The upper 16-bit value can
be read after the lower 16-bit value.

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-1616HS-2 that pulses once every scan period
to indicate the start of a scan group—latches the count so that 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.

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 13

. 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.

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USB-1616HS-2 User's Guide Functional Details

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 13. 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 14. Debounce module – trigger after stable mode

The following time periods (T1 through T5) pertain to Figure 14. 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.

 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.)

 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.

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

 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.

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USB-1616HS-2 User's Guide Functional Details

Figure 15. Debounce module – Trigger before stable mode

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

 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.

 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.

 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.

 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].

 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.

 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 16

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.

Figure 16. 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.

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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 17. 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 18

.

Figure 18. 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 USB-1616HS-2 supports quadrature encoders with up to 2 billion pulses per revolution, 20 MHz input
frequencies, and x1, x2, x4 count modes.

The encoder mode allows the USB-1616HS-2 to make use of data from optical incremental quadrature
encoders. In encoder mode, the USB-1616HS-2 accepts single-ended inputs. When reading phase A, phase B,
and index Z signals, the USB-1616HS-2 provides positioning, direction, and velocity data.

The USB-1616HS-2 can receive input from up to two encoders.

The USB-1616HS-2 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

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USB-1616HS-2 User's Guide Functional Details

A

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 -5V to +10V 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.

Figure 19. Representation of rotary shaft quadrature encoder

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.

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 will give 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 will lag 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 will give direction control as well as distance from the reference.

32

USB-1616HS-2 User's Guide Functional Details

1

g

2

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-1616HS-2 to an encoder

You can use up to two encoders with each USB-1616HS-2 in your acquisition system. Each A and B signal can
be made as a single-ended connection with respect to common ground.

Differential applications are not supported.

For single-ended applications:

 Connect signals A, B, and Z to the counter inputs on the USB-1616HS-2.
 Connect each encoder ground to GND.

You can also connect external pull-up resistors to the USB-1616HS-2 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-1616HS-2. 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 USB-1616HS-2 module.

Ground (to Digital Common1)
Counter 0 (CNT0) – To Encoder “A”
Counter 1 (CNT1) – To Encoder “B”

Counter 2 (CNT2) – To Encoder “Z”

The ground depicted at the left is associated with Digital Common on the USB-1616HS-4.

2

The ground depicted at the right is associated with the external power source.

To external power

round

To

Figure 21. Connections from single encoder to screw terminals on the USB-1616HS-2

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.

Connect each signal (A, B, Z) as a single-ended connection with respect to the common ground. The encoder
needs power from an external power output (typically +5 VDC). Connect the encoder's power input to the
power source and connect the return to the digital common of that source.

Wiring for two encoders: The following figure illustrates single-ended connections for two encoders.

Differential connections are not applicable.

33

USB-1616HS-2 User's Guide Functional Details

1

Each signal (A, B) can be connected as a single-ended connection with respect to the common digital ground
(GND). Both encoders need power from an external power source (typically +5 VDC).

Connect each encoder's power input to the external power source. Connect the return to digital common (GND)
on the same source.

Counter 0 (CNT0) – To Encoder #1 “A”
Counter 1 (CNT1) – To Encoder #1 “B”
Counter 2 (CNT2) – To Encoder #2 “A”
Counter 3 (CNT3) – To Encoder #2 “B”

Ground (to Digital Common1)

The ground depicted at the left is associated with Digital Common on the USB-1616HS-4.

2

The ground depicted at the right is associated with the external power source.

To external power
To ground2

Figure 22. Connections from two encoders to screw terminals on the USB-1616HS-2

Timer outputs

Two 16-bit timer outputs are built into every USB-1616HS-2. Each timer output can generate a different square
wave with a programmable frequency in the range of 16 Hz to 1 MHz.

Figure 23. Typical USB-1616HS-2 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.

Timer output frequency examples

Divisor Timer output frequency

1 1 MHz

100 10 kHz

1000 1 kHz

10000 100 Hz

65535

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

 15.259 Hz (in asynchronous write)
 Turns timer off (for setpoint operation).

34

USB-1616HS-2 User's Guide Functional Details

Both timer outputs can also be updated during an acquisition as the result of setpoints applied to analog or
digital inputs.

Using multiple USB-1616HS-2s per PC

USB-1616HS-2 features can be replicated up to four times, as up to four devices can be connected to a single
host PC. The serial number on each USB-1616HS-2 distinguishes one from another. You can operate multiple
USB-1616HS-2 boards synchronously. To do this, set up one USB-1616HS-2 with the pacer terminal you want
to use (APR or DPR) configured for output. Set up the USB-1616HS-2 boards you want to synchronize to this
board with the pacer screw terminal you want to use (APR or DPR) configured for input. Wire the pacer
terminal configured for output to each of the pacer input terminals that you want to synchronize.

To operate two or more USB-1616HS-2s synchronously:

 Use coax (or twisted-pair wire) to connect the output signal to the input(s).

 Connect Digital Common of each USB-1616HS-2 to one of the twisted pairs or to the shield of the coax.

Detection setpoint overview

You can program each as one of the following:

 Single point referenced – Above, below, or equal to the defined setpoint.
 Window (dual point) referenced – Inside or outside the window.
 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).

Figure 24. Diagram of detection setpoints

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 37.

35

USB-1616HS-2 User's Guide Functional Details

Criteria – input signal is equal to X Action - driven by condition

Compare
X to:

Limit A or
Limit B

Window*
(non-hyste
resis
mode)

Window*
(hysteresis
mode)

Setpoint definition
(choose one)

 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 (A < X < B) (Both

conditions are checked when
in hysteresis mode

Update conditions:

True only:

 If True, then output value 1
 If False, then perform no action

True and False:

 If True, then output value 1
 If False, then output value 2

True only

 If True, then output value 1
 If False, then perform no action

True and False

 If True, then output value 1
 If False, then output value 2

Hysteresis mode (forced update)
 If X > A is True, then output value 2 until X < B is True, then

output value 1.

 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, output value 2 until

the signal goes outside the window low, and
(b) if the signal is outside the window low, 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.)

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-1616HS-2 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.

36

USB-1616HS-2 User's Guide Functional Details

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-1616HS-2 through software.

Set low limit

You can set the 16-bit low limit (limit B) when configuring the USB-1616HS-2 through software.

Set criteria

 Inside window: Signal is below 16-bit high limit and above 16-bit low limit.
 Outside window: Signal is above 16-bit high limit, or below 16-bit low limit.
 Greater than value: Signal is above 16-bit low limit, so 16-bit high limit is not used.
 Less than value: Signal is below 16-bit high limit, so 16-bit low limit is not used.
 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

 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.

Set output channel

 None
 Update FIRSTPORTC
 Update DAC
 Update timerx

Update modes

 Update on True only
 Update on True and False

Set values for output

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

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USB-1616HS-2 User's Guide Functional Details

 A value of 0 indicates that the setpoint criteria are not met—in other words, the condition is False.
 A value of 1 indicates that the criteria have 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.

Setpoint # 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

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 table above we have 10011 binary, or 19 decimal, derived as follows:

 Setpoint 0, having a True state, shows 1, giving us decimal 1.
 Setpoint 1, having a True state, shows 1, giving us decimal 2.
 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.

Channel Condition State of detect signal Action

5

4

Below limit A (for
channel 5)

Within window
(between limit A and
limit B) for channel 4

True

False

True

False

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 - 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.

38

USB-1616HS-2 User's Guide Functional Details

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 -1.0 V.

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

Criteria Used: Inside window

Figure 27 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.

39

USB-1616HS-2 User's Guide Functional Details

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

Figure 28 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:

 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.

 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.

Figure 28. Channel 3 in hysteresis mode

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USB-1616HS-2 User's Guide Functional Details

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 3.0 V.

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 - 7.0 V.

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.

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).
Alternately, one of the DAC output channels, or timer outputs, could be updated with a value.

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USB-1616HS-2 User's Guide Functional Details

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.
Alternately, you can program each setpoint with a 16-bit DAC update value, and any one of the two DAC
outputs can be updated in real time. Any setpoint can also be programmed with 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 1µs, 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
the output scan 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:

 scan rate
 synchronous sampling mode
 type of output to be updated

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USB-1616HS-2 User's Guide Functional Details

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

, 100th, or nth 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:

 Shorten the scan period to give more timing resolution on the counter values or analog values.
 Widen the setpoint window by increasing limit A and/or lowering limit B.
 A combination of both solutions (1 and 2) could be made.

43

Chapter 4

Calibrating the USB-1616HS-2

Every range of a USB-1616HS-2 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
without destroying the factory calibration supplied with the board. This is accomplished by having two distinct
calibration tables in the USB-1616HS-2 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-1616HS-2 boards. You should calibrate the
USB-1616HS-2 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.

44

Chapter 5

Specifications

Typical for 25 °C unless otherwise specified.

Specifications in italic text are guaranteed by design.

Analog input

Table 1. Analog input specifications

A/D converter type Successive approximation

Resolution 16 bits

Number of channels 16 single-ended/8 differential, software-selectable.

Up to 48 additional analog inputs per module are available with the optional AI-EXP48
module. Expansion channel features are the same as those of the main channels.

Input ranges (software and
sequencer programmable)

Maximum sample rate 1 MHz

Nonlinearity (integral) ±2 LSB maximum

Nonlinearity (differential) ±1 LSB maximum
A/D pacing

Trigger sources and modes

Acquisition data buffer

Data transfer DMA
Configuration memory

Maximum usable input
voltage + common mode
voltage (CMV + Vin)

Signal to noise and distortion 72 dB typical for ±10 V range, 1 kHz fundamental

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

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

CMRR @ 60 Hz -70 dB typical DC to 1 kHz

Bias current 40 pA typical (0 °C to 35°C)

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

Input impedance 10 M single-ended, 20 M differential

Absolute maximum input
voltage

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

Onboard input scan clock, external source (APR)

See Table 8

1 MSample

Programmable I/O

Range: ±10 V, ±5 V, ±2 V, ±1 V, ±0.5 V 10.5 V maximum

Range: ±0.2 V, ±0.1 V 2.1 V maximum

±30 V

Accuracy

Table 2. Analog input accuracy specifications

Voltage range Accuracy

±(% of reading + %
range)
23°C ±10 °C, 1 year

-10 V to 10 V 0.031% + 0.008% 14 + 8 2.0

-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

0.031% + 0.009% 14 + 9

0.031% + 0.010% 14 +10

0.031% + 0.02% 14 + 12

0.031% + 0.04% 14 +18

0.036% + 0.075% 14 +12

0.042% + 0.15% 14 +18

Temperature coefficient
±(ppm of reading + ppm range)/°C

45

Noise (cts
RMS)

3.0

2.0

3.5

5.5

8.0

14.0

Note 2

USB-1616HS-2 User's Guide Specifications

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

Thermocouples

Table 3. Thermocouple (TC) types and accuracy (Note 3)

TC type Temperature range (°C) Accuracy (±°C) Noise typical (±°C)

J -200 to + 760 1.7 0.2

K -200 to + 1200 1.8 0.2

T -200 to + 400 1.8 0.2

E -270 to + 650 1.7 0.2

R -50 to + 1768 4.8 1.5

S -50 to + 1768 4.7 1.5

N -270 to + 1300 2.7 0.3

B +300 to + 1400 3.0 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
(1000 °C), TR-2U power supply for external power.

= 0° C for all types except B

in

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 2

Resolution 16-bits

Data buffer PC-based memory

Output voltage range ±10 V

Output current ±1 mA

Sourcing more current (1 to 10 mA) may require a TR-2U power supply.

Offset error ±0.0045 V maximum

Digital feed-through <10 mV when updated

DAC analog glitch <12 mV typical at major carry

Gain error ±0.01%

Coupling DC

Update rate 1 MHz maximum, resolution 20.83 ns

Settling time 2 µs to rated accuracy

Pacer sources Four programmable sources:

 Onboard output scan clock, independent of input scan clock
 Onboard input scan clock
 External output scan clock (DPR), independent of external input scan clock (APR)
 External input scan clock (APR)

Trigger sources Start of input scan

46

USB-1616HS-2 User's Guide Specifications

Digital input/output

Table 5. Digital input/output specifications

Number of I/O 24

Ports Three banks of eight.

Each port is programmable as input or output

Input scanning modes Two programmable

 Asynchronous, under program control at any time relative to input scanning
 Synchronous with input scanning

Input characteristics 220  series resistors, 20 pF to common

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

Input protection ±15 kV ESD clamp diodes parallel

Input high +2.0 V to +5.0 V

Input low 0 to 0.8 V

Output high >2.0 V

Output low <0.8 V

Output current Output 1.0 mA per pin

Sourcing more current may require a TR-2U power supply.

Digital input pacing Onboard input scan clock, external input scan clock (APR)

Digital output pacing Four programmable sources:

 Onboard output scan clock, independent of input scan clock
 Onboard input scan clock
 External output scan clock (DPR), independent of external input scan clock

(APR)

 External input scan clock (APR)

Digital input trigger sources and
modes

Digital output trigger sources Start of input scan

Data transfer DMA

Sampling/update rate 4 MHz maximum (rates up to 12 MHz are sustainable on some platforms)

Pattern generation output

See Table 8

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.

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USB-1616HS-2 User's Guide Specifications

Counters

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

Table 6. Counter specifications

Channels 4 independent

Resolution 32-bit

Input frequency 20 MHz maximum

Input signal range -5 V to 10 V

Input characteristics

Trigger level TTL

Minimum pulse width 25 ns high, 25 ns low

Debounce times

Time base accuracy 50 ppm (0 ° to 50 °C)

Counter read pacer Onboard input scan clock, external input scan clock (APR)

Trigger sources and modes See Table 8

Programmable mode Counter

Counter mode options

10 kΩ pull-up, 200 Ω series resistor, ±15 kV ESD protection

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

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

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, programmable:

 Analog channels from 1 µs to 1 s in 20.83 ns steps.
 Digital channels and counters from 250 ns to 1 s in 20.83 ns steps.

External. TTL level input (APR):

 Analog channels down to 1 µs minimum
 Digital channels and counters down to 250 ns minimum

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

Depth 512 locations

Onboard channel-to-channel scan rate Analog: 1 MHz maximum

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

External input scan clock (APR) maximum
rate

Clock signal range: Logical zero: 0 V to 0.8 V

Minimum pulse width 50 ns high, 50 ns low

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 clock rates up to 83.33 ns.

Analog: 1.0 MHz
Digital: 4 MHz if no analog channels are enabled, 1 MHz with analog

channels enabled

Logical one: 2.4 V to 5.0 V

48

USB-1616HS-2 User's Guide Specifications

Triggering

Table 8. Trigger sources and modes

Trigger source Explanation

Single channel analog
hardware trigger

Single channel analog
software trigger

External-single
channel digital trigger

Digital pattern
triggering

Counter/totalizer
triggering

Any analog input channel can be software programmed as
the analog trigger channel, including any of the analog expansion channels.

 Input signal range: -10 V to +10 V maximum
 Trigger level: Programmable (12-bit resolution)
 Latency: 350 ns typical, 1.3 µs max
 Accuracy: ±0.5% of reading, ±2 mV offset maximum
 Noise: 2 mV RMS typical

Any analog input channel—including any of the analog expansion channels, can be selected as
the software trigger channel. If the trigger channel involves a calculation, such as temperature,
then the driver automatically compensates for the delay required to obtain the reading, resulting
in a maximum latency of one scan period.

 Input signal range: Anywhere within range of the trigger channel
 Trigger level: Programmable (16-bit resolution)
 Latency: One scan period (maximum)

A separate digital input is provided for digital triggering.

 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

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

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

Table 9. Frequency/pulse generator specifications

Channels 2 × 16-bit

Output waveform Square wave

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

High-level output voltage 2.0 V minimum @ -1.0 mA, 2.9 V minimum @ -400 µA

Low-level output voltage 0.4 V maximum @ 400 µA

Power consumption

Power consumption specification is for a USB-1616HS-2. Add 400mW for a USB-1616HS-2 connected to an
AI-EXP48 expansion module.

Table 10. Power consumption specifications (Note 5)

Power consumption (per board) 3000 mW

49

USB-1616HS-2 User's Guide Specifications

External power

Table 11. External power specifications (Note 5)

Connector Switchcraft # RAPC-712

Power range

Over-voltage

Note 5: The power supply (MCC p/n TR-2U) and line cord (MCC p/n CA-1) are required if the USB port

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

cannot supply adequate power. By USB 2.0 standards, USB 2.0 ports must supply 2500 mW
(nominal at 5 V, 500 mA)

USB specifications

Table 12. USB specifications

USB-device type

Device compatibility

USB 2.0 high-speed mode (480 Mbps) if available (recommended), otherwise, USB1.1
full-speed mode (12 Mbps)

USB 2.0 (recommended) or USB 1.1

Environmental

Table 13. Environmental specifications

Operating temperature range -30 °C to +70 °C
Storage temperature range -40 °C to +80 °C
Relative humidity 0 to 95% non-condensing

Mechanical

Table 14. Mechanical specifications

Vibration MIL STD 810E category 1 and 10

Dimensions 269 mm (W) x 92 mm (D) x 45 mm (H )(10.6” x 3.6” x 1.6”)

Weight 431 g (0.95 lbs)

Signal I/O connectors and pin out

Table 15. Screw connector specifications

Connector type Screw terminal
Wire gauge range 14 AWG to 30 AWG
Expansion connector type 25-pin DSUB, female
Compatible expansion products AI-EXP48 expansion module with screw terminals

50

USB-1616HS-2 User's Guide Specifications

Table 16. USB-1616HS-2 screw terminal pin out – single-ended connections

Analog common (Ab) Digital common (Db)
Analog output 0 (AO0) FIRSTPORTA Bit 0 (A0)
Analog output 1 (AO1) FIRSTPORTA Bit 1 (A1)

NC FIRSTPORTA Bit 2 (A2)
NC FIRSTPORTA Bit 3 (A3)

Analog Out

Analog In

Analog In

CAL (Reserved for self-calibration) FIRSTPORTA Bit 5 (A5)

Analog common (Ab) FIRSTPORTA Bit 4 (A4)

Signal ground (Sb) FIRSTPORTA Bit 6 (A6)

Digital common (Db) FIRSTPORTA Bit 7 (A7)

TTL trigger (TRG)

Output scan clock I/O (DPR) Timer 0 (T0)

Input scan clock I/O (APR) Timer 1 (T1)

Analog common (Ab) Digital common (Db)

CH 0 (0H) FIRSTPORTB Bit 0 (B0)

CH 8 (8L) FIRSTPORTB Bit 1 (B1)

Analog common (Ab) FIRSTPORTB Bit 2 (B2)

CH 1 (1H) FIRSTPORTB Bit 3 (B3)

CH 9 (9L) FIRSTPORTB Bit 4 (B4)

Analog common (Ab) FIRSTPORTB Bit 5 (B5)

CH 2 (2H) FIRSTPORTB Bit 6 (B6)

CH 10 (10L) FIRSTPORTB Bit 7 (B7)

Analog common (Ab)

CH 3 (3H) Counter 0 (CT0)

CH 11 (11L) Counter 1 (CT1)

Analog common (Ab) Digital common (Db)

CH 4 (4H) FIRSTPORTC Bit 0 (C0)

CH 12 (12L) FIRSTPORTC Bit 1 (C1)

Analog common (Ab) FIRSTPORTC Bit 2 (C2)

CH 5 (5H) FIRSTPORTC Bit 3 (C3)

CH 13 (13L) FIRSTPORTC Bit 4 (C4)

Analog common (Ab) FIRSTPORTC Bit 5 (C5)

CH 6 (6H) FIRSTPORTC Bit 6 (C6)

CH 14 (14L) FIRSTPORTC Bit 7 (C7)

Analog common (Ab)

CH 7 (7H) Counter 2 (CT2)

CH 15 (15L) Counter 3 (CT3)

Port A

Digital common (Db)

Port B

Digital common (Db)

Port C

Digital common (Db)

DIG-Tmr I/O

Dig-Ctr I/O

Dig-Ctr I/O

51

USB-1616HS-2 User's Guide Specifications

Table 17. USB-1616HS-2 screw terminal pin out – differential connections

Analog common (Ab) Digital common (Db)
Analog output 0 (AO0) FIRSTPORTA Bit 0 (A0)
Analog output 1 (AO1) FIRSTPORTA Bit 1 (A1)

NC FIRSTPORTA Bit 2 (A2)
NC FIRSTPORTA Bit 3 (A3)

Analog Out

Analog In

Analog In

CAL (Reserved for self-calibration) FIRSTPORTA Bit 5 (A5)

Analog common (Ab) FIRSTPORTA Bit 4 (A4)

Signal ground (Sb) FIRSTPORTA Bit 6 (A6)

Digital common (Db) FIRSTPORTA Bit 7 (A7)

TTL trigger (TRG)

Output scan clock I/O (DPR) Timer 0 (T0)

Input scan clock I/O (APR) Timer 1 (T1)

Analog common (Ab) Digital common (Db)

CH 0 HI (0H) FIRSTPORTB Bit 0 (B0)

CH 0 LO (8L) FIRSTPORTB Bit 1 (B1)

Analog common (Ab) FIRSTPORTB Bit 2 (B2)

CH 1 HI (1H) FIRSTPORTB Bit 3 (B3)

CH 1 LO (9L) FIRSTPORTB Bit 4 (B4)

Analog common (Ab) FIRSTPORTB Bit 5 (B5)

CH 2 HI (2H) FIRSTPORTB Bit 6 (B6)

CH 2 LO (10L) FIRSTPORTB Bit 7 (B7)

Analog common (Ab)

CH 3 HI (3H) Counter 0 (CT0)

CH 3 LO (11L) Counter 1 (CT1)

Analog common (Ab) Digital common (Db)

CH 4 HI (4H) FIRSTPORTC Bit 0 (C0)

CH 4 LO (12L) FIRSTPORTC Bit 1 (C1)

Analog common (Ab) FIRSTPORTC Bit 2 (C2)

CH 5 HI (5H) FIRSTPORTC Bit 3 (C3)

CH 5 LO (13L) FIRSTPORTC Bit 4 (C4)

Analog common (Ab) FIRSTPORTC Bit 5 (C5)

CH 6 HI (6H) FIRSTPORTC Bit 6 (C6)

CH 6 LO (14L) FIRSTPORTC Bit 7 (C7)

Analog common (Ab)

CH 7 HI (7H) Counter 2 (CT2)

CH 7 LO (15L) Counter 3 (CT3)

Port A

Digital common (Db)

Port B

Digital common (Db)

Port C

Digital common (Db)

DIG-Tmr I/O

Dig-Ctr I/O

Dig-Ctr I/O

52

Declaration of Conformity

Manufacturer: IOTech, Incorporated
Address: 25971 Cannon Road
Cleveland, OH 44146
USA
Category: Information technology equipment.

IOTech, Incorporated declares under sole responsibility that the product

USB-1616HS-2

to which this declaration relates is in conformity with the relevant provisions of the following standards or other
documents:

EU EMC Directive 89/336/EEC: Electromagnetic Compatibility, EN 61326 (1997) Amendment 1 (1998)

Emissions: Group 1, Class A

 EN 55022 (1993)/CISPR 22: Radiated and Conducted emissions.

Immunity: EN61326, Annex A

 IEC 61000-4-2 (1995): Electrostatic Discharge immunity, Criteria B.
 IEC 61000-4-3 (1995): Radiated Electromagnetic Field immunity Criteria A.
 IEC 61000-4-4 (1995): Electric Fast Transient Burst immunity Criteria A.
 IEC 61000-4-6 (1996): Radio Frequency Common Mode immunity Criteria A.
 IEC 61000-4-11 (1994): Voltage Dips, Interruption immunity.

To maintain the safety, emission, and immunity standards of this declaration, the following conditions must be
met.

 The host computer, peripheral equipment, power sources, and expansion hardware must be CE compliant.
 Equipment must be operated in a controlled electromagnetic environment as defined by Standards EN

61326:1998, or IEC 61326:1998.



Shielded wires must be used for all I/Os and must be less than 3 meters (9.75 feet) in length. Clips must be used with
the AI-EXP48.

 The host computer must be properly grounded.


The host computer must be USB2.0 compliant and IOtech USB cables (CA-179-x) must be used.



If using the USB-1616HS Series device in a high RF environment (3 to 10 V/m), then a clamp-on ferrite (IOtech p/n L­8-1) may be needed on the USB cable, otherwise communication may be disrupted.



A protective ESD wrist strap should be used when connecting or disconnecting leads from screw terminal blocks.
Alternatively, unplug the unit from the host computer when making connections. Protective housings (IOtech p/n
CN-241-12) can be placed over the removable terminal blocks to protect signals from ESD during operation.



If external DC power is needed, a TR-2U power supply must be used.

Note: Data acquisition equipment may exhibit noise or increased offsets when exposed to high RF fields
(>3V/m) or transients.

Declaration of Conformity based on tests conducted by Smith Electronics, Inc., Cleveland, OH 44141, USA in
December, 2005. Test records are outlined in Smith Electronics Test Report “Personal Daq/3000 Series with
PDQ30 Expansion Module” and “PDAQ3000-PDQ30 Addenda”.

We hereby declare that the equipment specified conforms to the above Directives and Standards.

Paul Wittibschlager
Director of Hardware Engineering

Measurement Computing Corporation

10 Commerce Way

Suite 1008

Norton, Massachusetts 02766

[phone]

Fax: [phone]

E-mail: [e-mail]

www.mccdaq.com