Measurement Computing USB-1608FS User Manual

USB-1608FS

USB-based

Analog and Digital I/O Module

User's Guide

© Copyright 2006, Measurement Computing Corporation™

Document Revision 2, May, 2006

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Lifetime Harsh Environment Warranty®: We will replace any product manufactured by Measurement Computing
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HM USB-1608FS.doc

ii

Trademark and Copyright Information

TracerDAQ, Universal Library, InstaCal, Harsh Environment Warranty, Measurement Computing Corporation, and the
Measurement Computing logo are either trademarks or registered trademarks of Measurement Computing Corporation.

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iii

Table of Contents

Preface

About this User's Guide ......................................................................................................................vi

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

Conventions in this user's guide ........................................................................................................................vi

Where to find more information........................................................................................................................vi

Chapter 1

Introducing the USB-1608FS............................................................................................................ 1-1

USB-1608FS block diagram........................................................................................................................... 1-2

Software features............................................................................................................................................ 1-2

Connecting a USB-1608FS to your computer is easy..................................................................................... 1-3

Chapter 2

Installing the USB-1608FS................................................................................................................ 2-1

What comes with your USB-1608FS shipment? ............................................................................................ 2-1

Hardware ....................................................................................................................................................................... 2-1

Additional documentation.............................................................................................................................................. 2-1

Unpacking the USB-1608FS .......................................................................................................................... 2-1

Installing the software .................................................................................................................................... 2-2

Installing the hardware ................................................................................................................................... 2-2

Chapter 3

Functional Details ............................................................................................................................. 3-1

Theory of operation - analog input acquisition modes ................................................................................... 3-1

Software paced mode..................................................................................................................................................... 3-1

Continuous scan mode ................................................................................................................................................... 3-1

Burst scan mode............................................................................................................................................................. 3-1

External components ...................................................................................................................................... 3-2

USB connector............................................................................................................................................................... 3-2

LED ............................................................................................................................................................................... 3-2

Screw terminal wiring.................................................................................................................................................... 3-3

Main connector and pin out ........................................................................................................................................... 3-3

Analog input terminals (CH0 IN - CH7 IN)................................................................................................................... 3-4

Digital I/O terminals (DIO0 to DIO7)............................................................................................................................ 3-5

Power terminals ............................................................................................................................................................. 3-6

Ground terminals ...........................................................................................................................................................3-6

Calibration terminal ....................................................................................................................................................... 3-7

Counter terminal ............................................................................................................................................................ 3-7

SYNC terminal ..............................................................................................................................................................3-7

Trigger terminal............................................................................................................................................................. 3-7

Accuracy......................................................................................................................................................... 3-7

Gain queue.................................................................................................................................................... 3-10

Synchronizing multiple units........................................................................................................................ 3-10

Chapter 4

Specifications.................................................................................................................................... 4-1

Analog input section....................................................................................................................................... 4-1

Digital input/output......................................................................................................................................... 4-2

External trigger............................................................................................................................................... 4-2

External clock input/output............................................................................................................................. 4-3

Counter section............................................................................................................................................... 4-3

Memory .......................................................................................................................................................... 4-3

Microcontroller............................................................................................................................................... 4-4

iv

USB-1608FS User's Guide

Power.............................................................................................................................................................. 4-4

General ........................................................................................................................................................... 4-4

Environmental ................................................................................................................................................ 4-4

Mechanical ..................................................................................................................................................... 4-4

Main connector and pin out............................................................................................................................ 4-5

v

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-1608FS so that you get the most out of its
USB data acquisition features.

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

Conventions 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 helpful information relevant to the operation of the USB-1608FS.

! MCC's Specifications: USB-1608FS (the PDF version of the Electrical Specification Chapter in this guide)

is available on our web site at www.mccdaq.com/pdfs/USB-1608FS.pdf

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

! 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

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

! MCC's Universal Library for LabVIEW

.

.

™

User’s Guide is available on our web site at

.

USB-1608FS User's Guide (this document) is also available on our web site at

vi

Chapter 1

Introducing the USB-1608FS

This user's guide contains all of the information you need to connect the USB-1608FS to your computer and to
the signals you want to measure. The USB-1608FS is part of the Measurement Computing brand of USB-based
data acquisition products.

The USB-1608FS is a USB 2.0 full-speed device supported under popular Microsoft
systems. It is designed for USB 1.1 ports, and was tested for full compatibility with both USB 1.1 and USB 2.0
ports.

The USB-1608FS offers true simultaneous sampling of up to eight channels of 16-bit single-ended analog input.
This is accomplished through the use of one A/D converter per channel. The range of each channel is
independently configurable via software. Eight digital IO lines are independently selectable as input or output.
A 32-bit counter is capable of counting TTL pulses. The USB-1608FS is powered by the +5 volt USB supply
from your computer. No external power is required.

A SYNC (synchronization) control line allows you to synchronize two USB-1608FS modules together to
acquire data synchronously from 16 analog inputs.

The USB-1608FS is shown in Figure 1-1. I/O connections are made to the screw terminals located along each
side of the USB-1608FS.

®

Windows® operating

Figure 1-1. USB-1608FS

1-1

USB-1608FS User's Guide Introducing the USB-1608FS

A

A

A

A

A

A

A

A

USB-1608FS block diagram

USB-1608FS functions are illustrated in the block diagram shown here.

USB

G= 1, 2, 5, 10

Full-speed

USB 2.0

Compliant

Interface

DIO

SYNC

Screw terminal I/O connector

CAL

TRIG_IN

CAL

8

USB

Microcontroller

32k x 16

SRAM

1616

16

SPI

/D 0

/D 1

/D 2

/D 3

/D 4

/D 5

Screw terminal I/O connector

/D 6

/D 7

32-bit

Event Counter

1 channel

Figure 1-2. USB-1608FS Functional Block Diagram

Software features

For information on the features of InstaCal and the other software included with your USB-1608FS, refer to the
Quick Start Guide that shipped with your device. The Quick Start Guide is also available in PDF at

Check www.mccdaq.com/download.htm
under less commonly used operating systems.

.

for the latest software version or versions of the software supported

1-2

USB-1608FS User's Guide Introducing the USB-1608FS

Connecting a USB-1608FS to your computer is easy

Installing a data acquisition device has never been easier.

! The USB-1608FS relies upon the Microsoft Human Interface Device (HID) class drivers. The HID class

drivers ship with every copy of Windows that is designed to work with USB ports. We use the Microsoft
HID because it is a standard, and its performance delivers full control and maximizes data transfer rates for
your USB-1608FS. No third-party device driver is required.

! The USB-1608FS is plug-and-play. There are no jumpers to position, DIP switches to set, or interrupts to

configure.

! You can connect the USB-1608FS before or after you install the software, and without powering down

your computer first. When you connect an HID to your system, your computer automatically detects it and
configures the necessary software. You can connect and power multiple HID peripherals to your system
using a USB hub.

! You can connect your system to various devices using a standard four-wire cable. The USB connector

replaces the serial and parallel port connectors with one standardized plug and port combination.

! You do not need a separate power supply module. The USB automatically delivers the electrical power

required by each peripheral connected to your system.

! Data can flow two ways between a computer and peripheral over USB connections.

1-3

Installing the USB-1608FS

What comes with your USB-1608FS shipment?

The following items are shipped with the USB-1608FS.

Hardware

! USB-1608FS

Chapter 2

! USB cable (2 meter length)

Additional documentation

In addition to this hardware user's guide, you should also receive the Quick Start Guide (available in PDF at

the software you received with your USB-1608FS and information regarding installation of that software.
Please read this booklet completely before installing any software or hardware.

Unpacking the USB-1608FS

As with any electronic device, you should take care while handling to avoid damage from static
electricity. Before removing the USB-1608FS 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]

2-1

USB-1608FS User's Guide Installing the USB-1608FS

Installing the software

Quick-Start.pdf.

Installing the hardware

Be sure you are using the latest system software

Before you connect the USB-1608FS, make sure that you are using the latest versions of the USB drivers.

Before installing the USB-1608FS, download and install the latest Microsoft Windows updates. In particular,
when using Windows XP, make sure you have XP Hotfix KB822603 installed. This update is intended to
address a serious error in Usbport.sys when you operate a USB device. You can run Windows Update or
download the update from www.microsoft.com/downloads/details.aspx?familyid=733dd867-56a0-4956-b7fe-

e85b688b7f86&displaylang=en. For more information, refer to the Microsoft Knowledge Base article

"Availability of the Windows XP SP1 USB 1.1 and 2.0 update." This article is available at

support.microsoft.com/?kbid=822603.

To connect the USB-1608FS to your system, turn your computer on, and connect the USB cable to a USB port
on your computer or to an external USB hub that is connected to your computer. The USB cable provides power
and communication to the USB-1608FS.

The USB-1608FS installs as a composite device with separate devices attached. When you connect the USB­1608FS for the first time, Found New Hardware popup balloons (Windows XP) or dialogs (other Windows
version) open as each USB-1608FS interface is detected.

It is normal for multiple dialogs to open when you connect the USB-1608FS for the first time. For additional
information, refer to the "Notes on installing and using the USB-1608FS" that was shipped with the USB­1608FS.

When the last balloon or dialog closes, the installation is complete. The LED on the USB-1608FS should flash
and then remain lit. This indicates that communication is established between the USB-1608FS and your
computer.

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

USB-1608FS, or you may lose data and/or your ability to communicate with the USB-1608FS.

If the LED turns off

If the LED is lit but then turns off, the computer has lost communication with the USB-1608FS. To restore
communication, disconnect the USB cable from the computer, and then reconnect it. This should restore
communication, and the LED should turn back on.

2-2

Chapter 3

Functional Details

Theory of operation - analog input acquisition modes

The USB-1608FS can acquire analog input data in three basic modes – software paced, continuous scan, and
burst scan.

Software paced mode

You can acquire one analog sample at a time in software paced mode. You initiate the A/D conversion by
calling a software command. The analog value is converted to digital data and returned to the computer. You
can repeat this procedure until you have the total number of samples that you want from one channel.

The maximum throughput sample rate in software paced mode is system-dependent.

Continuous scan mode

You can acquire data from up to eight channels simultaneously in continuous scan mode. The analog data is
continuously acquired, converted to digital values, and written to an on-board FIFO buffer on the USB-1608FS
until you stop the scan. The FIFO buffer is serviced in blocks as the data is transferred from the USB-1608FS
FIFO buffer to the memory buffer on your computer.

The maximum sampling rate is an aggregate rate, where the total sample rate for all channels is 100 kS/s
divided by the number of channels, with a maximum rate of 50 kS/s for any channel. Using this equation, you
can acquire data with the USB-1608FS from one channel at 50 kS/s, two channels at 50 kS/s each, four
channels at 25 kS/s each, and so on, up to eight channels at 12.5 kS/s each. You can start a continuous scan with
either a software command or with an external hardware trigger event.

Burst scan mode

In burst scan mode, you can acquire data with the USB-1608FS using the full capacity of its 32 K sample FIFO.
The acquired data is then read from the FIFO and transferred to a user buffer in your computer. You can initiate
a single acquisition sequence of one, two, four, or eight channels by either a software command or an external
hardware trigger.

Burst scans are limited to the depth of the on-board memory, as the data is acquired at a rate faster than it can be
transferred to the computer. The maximum sampling rate is an aggregate rate, where the total acquisition rate
for all channels is 200 kS/s divided by the number of channels, with a maximum rate of 50 kS/s for any channel.
The maximum rate that you can acquire data using burst scan mode is 50 kS/s each for one, two, or four
channels, and 25 kS/s each for eight channels.

3-1

USB-1608FS User's Guide Functional Details

External components

The USB-1608FS has the following external components, as shown in Figure 3-1.

! USB connector
! LED
! Screw terminal banks (2)

Screw terminal
Pins 1 to 20

Screw terminal

Pins 21 to 40

LED

USB connector
/ cable

Figure 3-1. USB-1608FS

USB connector

The USB connector is on the right side of the USB-1608FS. This connector provides +5 V power and
communication. The voltage supplied through the USB connector is system-dependent, and may be less than 5
V. No external power supply is required.

LED

The LED on the front of the USB-1608FS indicates the communication status. It uses up to 5 mA of current and
cannot be disabled. explains the function of the USB-1608FS LED. Table 3-1

When the LED is… It indicates…

Steady green The USB-1608FS is connected to a computer or external USB hub.

Blinks continuously Data is being transferred.

Blinks three times Initial communication is established between the USB-1608FS and the computer.

Blinks at a slow rate

The analog input is configured for external trigger. The LED stops blinking and illuminates
steady green when the trigger is received.

Table 3-1 LED Illumination

3-2

USB-1608FS User's Guide Functional Details

Screw terminal wiring

The USB-1608FS has two rows of screw terminals—one row on the top edge of the housing, and one row on
the bottom edge. Each row has 20 connections. Pin numbers are identified in Fi . gure 3-2

Figure 3-2. USB-1608FS screw terminal pin numbers

Screw terminal – pins 1-20

The screw terminals on the top edge of the USB-1608FS (pins 1 to 20) provide the following connections:

! Eight analog input connections (
! Eleven analog ground connections (

CH0 IN to CH7 IN)

AGND)

! One calibration output terminal (CAL)

Screw terminal – pins 21-40

The screw terminals on the bottom edge of the USB-1608FS (pins 21 to 40) provide the following connections:

! Eight digital I/O connections (

DIO0 to DIO7)

! One external trigger source (TRIG_IN)
! One external event counter connection (
! One power connection (

PC+5 V)

CTR)

! One SYNC terminal for external clocking and multi-unit synchronization (SYNC)
! Eight ground connections (

GND)

Main connector and pin out

Connector type Screw terminal

Wire gauge range 16 AWG to 30 AWG

3-3

USB-1608FS User's Guide Functional Details

5 IN

AGND

AGND

AGND

AGND

CH7 IN

AGND

CH6 IN

AGND

AGND

CH4 IN

AGND

CH

201918

17 CAL161514131211109

8

7CH3 IN

6AGND

5CH2 IN

4AGND

3CH1 IN

2AGND

1CH0 IN

GND 40

PC +5V 39

CTR 38

TRIG_IN 37

SYNC 36

DIO7 35

GND 34

DIO6 33

GND 32

DIO5 31

GND 30

DIO4 29

GND 28

DIO3 27

GND 26

DIO2 25

GND 24

DIO1 23

GND 22

DIO0 21

Analog input terminals (CH0 IN - CH7 IN)

You can connect up to eight analog input connections to the screw terminal containing pins 1 to 20 (CH0 IN
through CH7 IN.) Refer to the pinout diagram on page 3-3 for the location of these pins. We recommend that
you connect unused analog input terminals to ground terminals during operation. For example, if you are not
using terminal 15 (CH7 IN), connect this terminal to terminal 16 (AGND).

Input configuration

All of the analog input channels are configured for single-ended input mode. Each analog signal is referenced to
signal ground (AGND), and requires two wires:

! The wire carrying the signal to be measured connects to CH# IN.
! The second wire connects to AGND.

The input voltage ranges are ±10 V, ±5 V, ±2.0 V, ±1.0 V. The following image illustrates a typical single­ended measurement connection.

Figure 3-3. Single-Ended measurement connection

Pin 1
CH0 IN

3-4

Pin 2
AGND

USB-1608FS User's Guide Functional Details

The following image shows the single-ended measurement data acquired by TracerDAQ.

Figure 3-4. TracerDAQ showing single-ended measurement data

For more information on analog signal connections

For more information on single-ended inputs, refer to the Guide to Signal Connections (this document is
available on our web site at www.mccdaq.com/signals/signals.pdf).

Digital I/O terminals (DIO0 to DIO7)

You can connect up to eight digital I/O lines to the screw terminal containing pins 21 to 40 (DIO0 to DIO7).
Refer to the pinout diagram on page 3-3 for the location of these pins. You can configure each digital bit for
either input or output. All digital I/O lines are pulled up to USB +5 V with a 47 K resistor (default). You can
request the factory to configure the resistor for pull-down to ground if desired.

When you configure the digital bits for input, you can use the USB-1608FS digital I/O terminals to detect the
state of any TTL-level input. Refer to the switch circuit shown in and the schematic shown in

. If you set the switch to the +5 V input, DIO0 reads

3-6

TRUE (1). If you move the switch to GND, DIO0 reads

FALSE (0).

Pin 39

PC +5V

Figure 3-5

Pin 21

DIO0

Figure

Figure 3-5. Digital connection DIO0 detecting the state of a switch

Pin 40

GND

3-5

USB-1608FS User's Guide Functional Details

DIO0

+5V+GND

Figure 3-6. Schematic showing switch detection by digital channel DIO0

For more information on digital signal connections

For general information regarding digital signal connections and digital I/O techniques, refer to the Guide to

Signal Connections (available on our web site at www.mccdaq.com/signals/signals.pdf).

Power terminals

The PC +5 V connection (pin 39) is on the bottom screw terminal of the USB-1608FS. Refer to the pinout
diagram on page 3-3 for the location of this pin. This terminal draws power from the USB connector. The +5 V
screw terminal is a 5 volt output that is supplied by the computer.

Caution! The +5 V terminal is an output. Do not connect to an external power supply or you may damage

the USB-1608FS and possibly the computer.

The maximum total output current that can be drawn from all USB-1608FS connections (power, analog, and
digital outputs) is 500 mA. This maximum applies to most personal computers and self-powered USB hubs.
Bus-powered hubs and notebook computers may limit the maximum available output current to 100 mA.

The USB-1608FS alone draws 150 mA of current from the USB +5 V supply. Once you start running
applications with the USB-1608FS, each DIO bit can draw up to 2.5 mA. The maximum amount of +5 V
current available for experimental use, over and above that required by the USB-1608FS, is the difference
between the total current requirement of the USB-1608FS (based on the application), and the allowed current
draw of the computer platform (500 mA for desktop computers and self-powered hubs).

With all outputs at their maximum output current, you can calculate the total current requirement of the USB­1608FS USB +5 V as follows:

(USB-1608FS @ 150 mA) + (8 DIO @ 2.5 mA ea) = 170 mA

For an application running on a computer or powered hub, the maximum available excess current is 500 mA −
170 mA = 330 mA. This number is the total maximum available current at the PC+5 V screw terminals.
Measurement Computing highly recommends that you figure in a safety factor of 20% below this maximum
current loading for your applications. A conservative, safe user maximum in this case would be in the 250­300 mA range.

Since some laptop computers running on battery power only allow up to 100 mA, the USB-1608FS may be
above that allowed by the computer. In this case, you must either purchase a self-powered hub or operate the
laptop computer from an external power adapter.

Ground terminals

The 11 analog ground connections provide a common ground for all USB-1608FS input channels. Eight ground
connections provide a common ground for the
the pinout diagram on page 3-3 for the location of the

DIO, TRIG_IN, CTR, SYNC and PC +5 V connections. Refer to

AGND and GND terminal pins.

3-6

USB-1608FS User's Guide Functional Details

Calibration terminal

The CAL connection (pin 17) is an output you should use only to calibrate the USB-1608FS. Refer to the pinout
diagram on page 3-3 for the location of this pin. Calibration of the USB-1608FS is software-controlled by

InstaCal.

Counter terminal

The CTR connection (pin 38) is a TTL-level input to a 32-bit event counter. Refer to the pinout diagram on page
3-3 for the location of this pin. The internal counter increments when the TTL level transitions from low to
high. The counter can count frequencies of up to 1 MHz.

SYNC terminal

The SYNC connection (pin 36) is a bidirectional I/O signal. You can use it for two purposes:

! Configure as an external clock input to externally source the A/D conversions. The SYNC terminal

supports TTL-level input signals of up to 50 kHz.

! Configure as an output to synchronize with a second USB-1608FS and acquire data from 16 channels.

Refer to the pinout diagram on page 3-3 for the location of this pin. For more information, refer to page 3-10.

Trigger terminal

The TRIG_IN connection (pin 37) is an external digital trigger input. You can configure this terminal with
software for either rising or falling edge.

Accuracy

The overall accuracy of any instrument is limited by the error components within the system. Quite often,
resolution is incorrectly used to quantify the performance of a measurement product. While "16-bits" or "1 part
in 65536" does indicate what can be resolved, it provides little insight into the quality, or accuracy, of an
absolute measurement. Accuracy specifications describe the actual measurement that can be relied upon with a
USB-1608FS.

There are three types of errors which affect the accuracy of a measurement system:

! offset
! gain
! nonlinearity

The primary error sources in the USB-1608FS are offset and gain. Nonlinearity is small in the USB-1608FS,
and is not significant as an error source with respect to offset and gain.

Figure 3-7 shows an ideal, error-free, USB-1608FS transfer function. The typical calibrated accuracy of the
USB-1608FS is range-dependent, as explained in the "Specifications
±10 V range as an example of what you can expect when performing a measurement in this range.

" chapter of this document. We use a

3-7

USB-1608FS User's Guide Functional Details

e

Input Voltage

+10V

Output Code

0

32768

65535

-10V

Figure 3-7. Ideal ADC transfer function

The USB-1608FS offset error is measured at mid-scale. Ideally, a zero volt input should produce an output code
of 32768. Any deviation from this is an offset error. shows the USB-1608FS transfer function with

Figure 3-8
an offset error. The typical offset error specification for the USB-1608FS on the ±10 V range is ±1.66 mV.
Offset error affects all codes equally by shifting the entire transfer function up or down along the input voltage
axis.

The accuracy plots in Figure 3-8 are drawn for clarity and are not drawn to scale.

Input Voltag

+10V

Ideal

0

Actual

Offset=1.66mV

32768

1.66mV

65535

Output Code

-10V

Figure 3-8. ADC transfer function with offset error

Gain error is a change in the slope of the transfer function from the ideal, and is typically expressed as a
percentage of full-scale. Figu shows the USB-1608FS transfer function with gain error. Gain error is

re 3-9

easily converted to voltage by multiplying the full-scale input (±10 V) by the error.

3-8

USB-1608FS User's Guide Functional Details

The accuracy plots in Figure 3-9 are drawn for clarity and are not drawn to scale.

Input Voltage

+10V

Ideal

Gain error = +0.04%, or +4mV
Gain error = -0.04%, or -4mV

Actual

Output Code

0

32768

65535

-10V

Figure 3-9. ADC Transfer function with gain error

For example, the USB-1608FS exhibits a typical calibrated gain error of ±0.04% on all ranges. For the ±10 V
range, this would yield 10 V × ±0.0002 = ±4 mV. This means that at full scale, neglecting the effect of offset for
the moment, the measurement would be within 4 mV of the actual value. Note that gain error is expressed as a
ratio. Values near ±FS (±10 V) are more affected from an absolute voltage standpoint than are values near mid­scale, which see little or no voltage error.

Combining these two error sources in , we have a plot of the error band of the USB-1608FS at ±full

Figure 3-10

scale (±10 V). This plot is a graphical version of the typical accuracy specification of the product.

The accuracy plots in Figure 3-10 are drawn for clarity and are not drawn to scale.

Ideal +1.66mV + 4mV

Ideal

Ideal -(1.66mV + 4mV)

Input Voltage

+10V

1.66mV

0

32768

-10V

Figure 3-10. Error band plot

Ideal +1.66mV + 4mV

Ideal

Ideal -(1.66mV + 4mV)

Output Code

65535

3-9

USB-1608FS User's Guide Functional Details

Gain queue

The USB-1608FS gain queue allows you to set up a different gain setting for each channel. The gain queue
removes the restriction of having a single gain for all channels. This feature creates a gain list which is written
to local memory on the USB-1608FS. The gain list is made up of a channel number and range setting. An
example of an eight-element list is shown in . Table 3-2

Table 3-2. Sample channel gain queue list

Element Channel Range

0 CH0 BIP10V

1 CH1 BIP5V

2 CH2 BIP10V

3 CH3 BIP1V

4 CH4 BIP2V

5 CH5 BIP10V

6 CH6 BIP1V

7 CH7 BIP5V

Note that the gain queue must contain eight elements that include all eight channels. You must carefully match
the gain to the expected voltage range on the associated channel
occur. Although this condition does not damage the USB-1608FS, it does produce a useless full-scale reading.
It can also introduce a long recovery time due to saturation of the input channel.

— otherwise, an over range condition can

Synchronizing multiple units

You can connect the SYNC pin of two USB-1608FS units together in a master/slave configuration and acquire
data synchronously from 16 channels. When the SYNC pin is configured as an output, the internal A/D pacer
clock signal is sent to the screw terminal. You can output the clock to the SYNC pin of a second USB-1608FS
configured for A/D pacer input.

You set the function of the SYNC pin (pin 36) for pacer input or pacer output by using
SYNC pin is set for pacer input. To synchronize a master USB-1608FS with a slave USB-1608FS and acquire
data from 16 channels, follow the steps below:

1.

Run InstaCal.

2.

Double-click on the USB-1608FS listing on the PC Board List on the InstaCal main form. The Board

Configuration

3.

Configure the SYNC pin of the master USB-1608FS for pacer output:

o

Double-click on the USB-1608FS that you want to configure as the master. The Board Configuration

dialog displays.

dialog opens.

o

Click to select the Enable Sync output check box and then click OK.

4.

Configure the SYNC pin of the slave USB-1608FS for pacer input:

o

Double-click on the USB-1608FS that you want to configure as the slave. The Board Configuration
dialog displays.

InstaCal. By default, the

o

Make sure that the Enable Sync output check box is not checked (unchecked is the default setting).

5. Connect the SYNC pin on the master USB-1608FS to the SYNC pin on the slave USB-1608FS.

3-10

USB-1608FS User's Guide Functional Details

6. Set the Universal Library EXTCLOCK option with cbAInScan()/AInScan() for the slave USB-1608FS to

enable pacer output.

An example of a master/slave configuration is shown below.

Figure 3-11. Configuring for synchronous data acquisition

When you are operating one USB-1608FS, do not set the EXTCLOCK option unless you are using an external
clock for A/D pacing.

3-11

Chapter 4

Specifications

Typical for 25 °C unless otherwise specified.

Specifications in italic text are guaranteed by design.

Analog input section

Table 1. Analog input specifications

Parameter Conditions Specification

A/D converter type 16-bit successive Approximation type

Number of channels 8 single-ended

Input configuration Individual A/D per channel

Sampling method Simultaneous

Absolute maximum input voltage CHx IN to GND. ±15 V max

Input impedance 100 MOhm, min

Input ranges Software selectable ±10 V, ±5 V, ±2 V, ±1 V

Sampling rate

Throughput

Gain queue

Resolution 16 bits

No missing codes 15 bits

Crosstalk Signal DC-25 KHz -80 dB

CAL output User calibration source

CAL output accuracy (Note 2) ±0.5% typ, ±1.0% max

CAL current ±5 mA max

Trigger source Software selectable External digital: TRIG_IN

Note 1:

Maximum throughput scanning to PC memory is machine dependent. While the majority of XP
equipped PC’s we tested allowed acquisition at the maximum rates, a few would not. The lowest
maximum rate we observed on an XP equipped PC during multi-channel testing was 95 kS/s,
aggregate. The rates specified are for Windows XP only. Maximum rates on operating systems
that predate XP may be less and must be determined through testing on your machine.

Scan to PC memory

Burst scan to 32 k sample FIFO

Software paced 500 S/s all channels

Scan to PC memory (Note 1)

Burst scan to 32 k
sample FIFO

0.6 S/s to 50 kS/s, software
programmable

20 S/s to 50 kS/s, software
programmable

= (100 kS/s) / (# of channels), max of
50 kS/s for any channel

= (200 kS/s) / (# of channels), max of
50 kS/s for any channel

Software configurable. Eight elements,
one gain element per channel.

0.625 V, 1.25 V, 2.5 V, 5.0 V, software
selectable

Note 2:

Range Accuracy (mV)

±10 V 5.66

±5 V 2.98

±2 V 1.31

±1 V 0.68

Actual values used for calibration are measured and stored in EEPROM.

Table 2. Calibrated absolute accuracy

4-1

USB-1608FS User's Guide Specifications

Table 3. Accuracy components - All values are (±)

Range % of Reading Gain error at FS (mV) Offset (mV)

±10 V 0.04 4.00 1.66

±5 V 0.04 2.00 0.98

±2 V 0.04 0.80 0.51

±1 V 0.04 0.40 0.28

Table 4

summarizes the noise performance for the USB-1608FS. Noise distribution is determined by gathering
50 K samples with inputs tied to ground at the user connector. Samples are gathered at the maximum specified
sampling rate of 50 kS/s.

Table 4. Noise performance

Range Typical counts LSBrms

±10 V 10 1.52

±5 V 10 1.52

±2 V 11 1.67

±1 V 14 2.12

Digital input/output

Table 5. Digital I/O specifications

Digital type CMOS

Number of I/O 8 (DIO0 through DIO7)

Configuration Independently configured for input or output

Pull-up/pull-down configuration

Input high voltage 2.0 V min, 5.5 V absolute max

Input low voltage 0.8 V max, –0.5 V absolute min

Output high voltage (IOH = –2.5 mA) 3.8 V min

Output low voltage (IOL = 2.5 mA) 0.7 V max

Power on and reset state Input

All pins pulled up to Vs via 47 K resistors (default).
Positions available for pull down to ground. Hardware
selectable via zero ohm resistors as a factory option.

External trigger

Parameter Conditions Specification

Trigger source (Note 3) External digital TRIG_IN

Trigger mode Software selectable

Trigger latency 10 µs max

Trigger pulse width 1µs min

Input high voltage 4.0 V min, 5.5 V absolute max

Input low voltage 1.0 V max, –0.5 V absolute min

Input leakage current ±1.0µA

Note 3: TRIG_IN is a Schmitt trigger input protected with a 1.5K Ohm series resistor.

Table 6. External trigger specifications

Edge sensitive: user configurable for
CMOS compatible rising or falling edge.

4-2

USB-1608FS User's Guide Specifications

External clock input/output

Table 7. External clock I/O specifications

Parameter Conditions Specification

Pin name SYNC

Pin type Bidirectional

Output Outputs internal A/D pacer clock. Software selectable direction

Input

Input clock rate 50 kHz, maximum

Input 1µs min Clock pulse width

Output 5µs min

Input leakage current ±1.0µA

Input high voltage 4.0 V min, 5.5 V absolute max

Input low voltage 1.0 V max, –0.5 V absolute min

IOH = –2.5 mA 3.3 V min Output high voltage (Note 4)

No load 3.8 V min

IOL = 2.5 mA 1.1 V max Output low voltage (Note 4)

No Load 0.6 V max

Note 4: SYNC is a Schmitt trigger input and is over-current protected with a 200 Ohm series resistor.

Receives A/D pacer clock from external
source.

Counter section

Table 8. Counter specifications

Pin name (Note 5) CTR

Counter type Event counter

Number of channels 1

Input type TTL, rising edge triggered

Input source CTR screw terminal

Resolution 32 bits

Schmidt trigger hysteresis 20 mV to 100 mV

Input leakage current ±1µA

Maximum input frequency 1 MHz

High pulse width 500 ns min

Low pulse width 500 ns min

Input high voltage 4.0 V min, 5.5 V absolute max

Input low voltage 1.0 V max, –0.5 V absolute min

Note 5: CTR is a Schmitt trigger input protected with a 1.5K Ohm series resistor.

Memory

Table 9. Memory specifications

Data FIFO 32,768 samples, 65,536 bytes

EEPROM 1,024 bytes

EEPROM configuration

Address range Access Description

0x000-0x07F Reserved 128 bytes system data

0x080-0x1FF Read/write 384 bytes cal data

0x200-0x3FF Read/write 512 bytes user area

4-3

USB-1608FS User's Guide Specifications

Microcontroller

Table 10. Microcontroller specifications

Type High performance 8-bit RISC microcontroller

Program memory 16,384 words

Data memory 2,048 bytes

Power

Parameter Conditions Specification

Supply current USB enumeration < 100 mA

Supply current (Note 6) Continuous mode 150 mA

+5 V USB power available
(Note 7)

Output current (Note 8) 350 mA max

Note 6:

This is the total current requirement for the USB-1608FS which includes up to 10 mA for the

! Connected to self-powered hub
! Connected to externally-powered root port hub

status LED.

4.5 V min, 5.25 V max

Note 7:

"Self-powered hub" refers to a USB hub with an external power supply. Self-powered hubs allow
a connected USB device to draw up to 500 mA. "Root port hubs" reside in the PC’s USB host
Controller. The USB port(s) on your PC are root port hubs. All externally-powered root port hubs
(desktop PC’s) provide up to 500 mA of current for a USB device. Battery-powered root port
hubs provide 100 mA or 500 mA, depending upon the manufacturer. A laptop PC that is not
connected to an external power adapter is an example of a battery-powered root port hub. If your
laptop PC is constrained to the 100 mA maximum, you need to purchase a self-powered hub.

Note 8:

This refers to the total amount of current that can be sourced from the USB +5 V and digital
outputs.

General

Device type USB 2.0 (full-speed)

Device compatibility USB 1.1, USB 2.0

Environmental

Operating temperature range 0 to 70 °C

Storage temperature range -40 to 70 °C

Humidity 0 to 90% non-condensing

Mechanical

Dimensions 79 mm (L) x 82 mm (W) x 25 mm (H)

USB cable length 3 meters max

User connection length 3 meters max

4-4

USB-1608FS User's Guide Specifications

Main connector and pin out

Connector type Screw terminal

Wire gauge range 16 AWG to 30 AWG

Pin Signal Name Pin Signal Name

1 CH0 IN 21 DIO0
2 AGND 22 GND
3 CH1 IN 23 DIO1
4 AGND 24 GND
5 CH2 IN 25 DIO2
6 AGND 26 GND
7 CH3 IN 27 DIO3
8 AGND 28 GND
9 CH4 IN 29 DIO4
10 AGND 30 GND
11 CH5 IN 31 DIO5
12 AGND 32 GND
13 CH6 IN 33 DIO6
14 AGND 34 GND
15 CH7 IN 35 DIO7
16 AGND 36 SYNC
17 CAL 37 TRIG_IN
18 AGND 38 CTR
19 AGND 39 PC +5V
20 AGND 40 GND

4-5

Declaration of Conformity

Manufacturer: Measurement Computing Corporation
Address: 10 Commerce Way
Suite 1008
Norton, MA 02766
USA

Category: Electrical equipment for measurement, control and laboratory use.

Measurement Computing Corporation declares under sole responsibility that the product

USB-1608FS

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 55011 (1990)/CISPR 11: Radiated and Conducted emissions.

Immunity: EN61326, Annex A

! IEC 1000-4-2 (1995): Electrostatic Discharge immunity, Criteria A.
!

IEC 1000-4-3 (1995): Radiated Electromagnetic Field immunity Criteria A.

! IEC 1000-4-8 (1994): Power Frequency Magnetic Field immunity Criteria A.

Declaration of Conformity based on tests conducted by Chomerics Test Services, Woburn, MA 01801, USA in
May, 2004. Test records are outlined in Chomerics Test Report #EMI3876.04.

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

Carl Haapaoja, Director of Quality Assurance

Measurement Computing Corporation

10 Commerce Way

Suite 1008

Norton, Massachusetts 02766

[phone]

Fax: [phone]

E-mail: [e-mail]

www.mccdaq.com