USB-202 Analog and Digital I/O User's Guide Document Revision 3 November 2014 © Copyright 2014
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Table of Contents Preface About this User's Guide ....................................................................................................................... 5 What you will learn from this user's guide ......................................................................................................... 5 Conventions in this user's guide .........................................................................................................................
USB-202 User's Guide USB specifications ........................................................................................................................................... 19 Environmental .................................................................................................................................................. 19 Mechanical .......................................................................................................................................................
Preface About this User's Guide What you will learn from this user's guide This user's guide describes the Measurement Computing USB-202 data acquisition device and lists device specifications. Conventions in this user's guide For more information Text presented in a box signifies additional information related to the subject matter. Caution! Shaded caution statements present information to help you avoid injuring yourself and others, damaging your hardware, or losing your data.
Chapter 1 Introducing the USB-202 The USB-202 is a USB 2.
Chapter 2 Installing the USB-202 Unpacking As with any electronic device, you should take care while handling to avoid damage from static electricity. Before removing the device 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. Contact us immediately if any components are missing or damaged.
Chapter 3 Functional Details Analog input acquisition modes The USB-202 can acquire analog input data in two different modes – software paced and hardware paced. Software paced mode You can acquire one analog sample at a time in software paced mode. You initiate the A/D conversion with a software command. The analog value is converted to digital and returned to the computer. You can repeat this procedure until you have the total number of samples that you want.
USB-202 User's Guide Functional Details Screw terminals The screw terminals provide the following connections: Eight single-ended analog inputs (CH0 to CH7) Two analog outputs (AOUT0 and AOUT1) Eight digital I/O (DI00 to DI07) External pacer clock input (AICKI) External pacer clock output (AICKO) Digital trigger input (TRIG) Counter input (CTR) User voltage output (+VO) Analog ground reference (AGND) and digital ground reference (GND) Figure 3.
USB-202 User's Guide Functional Details Signal connections Analog input You can connect up to 8 single-ended inputs to screw terminals CH0 to CH7. The input voltage range is ±10 V. Single-ended mode requires two wires; connect one wire to the signal you want to measure (CHx), and connect a second wire to the analog ground reference (AGND). External clock I/O The USB-202 provides one external clock input ( AICKI) and one clock output ( AICKO) for the analog input pacer.
USB-202 User's Guide Functional Details Figure 5 shows the location of jumper W4 in relation to the USB connector. Figure 5. Jumper W4 location Jumper W4 is configured by default for pull-down; see Figure 6. Figure 6. Jumper W4 pull-up/down configuration To pull the digital inputs high (+5V), configure the jumper for pull-up. Proper LED alignment When placing the circuit board within the housing, align the board LEDs with the top of the housing before attaching the housing bottom.
USB-202 User's Guide Functional Details Mechanical drawings Figure 7.
USB-202 User's Guide Functional Details Figure 8.
Chapter 4 Specifications All specifications are subject to change without notice. Typical for 25 °C unless otherwise specified. Specifications in italic text are guaranteed by design. Analog input Table 1.
USB-202 User's Guide Specifications Noise performance For the peak to peak noise distribution test, the input channel is connected to AGND at the input terminal block, and 12,000 samples are acquired at the maximum throughput. Table 3. Noise performance specifications Range Counts LSBrms ±10 V 5 0.76 Analog input calibration Table 4.
USB-202 User's Guide Specifications Digital input/output Table 8. Digital input specifications Parameter Specification Digital type Number of I/O Configuration Pull-up configuration TTL 8 Each bit may be configured as input (power on default) or output The port has 47 kΩ resistors that may be configured as pull-up or pull-down with an internal jumper. The factory configuration is pull-down.
USB-202 User's Guide Specifications External pacer input/output Table 7.
USB-202 User's Guide Specifications Counter Table 8. CTR specifications Parameter Specification Pin name Number of channels Resolution Counter type Input type Counter read/write rates (software paced) CTR 1 channel 32-bit Event counter Schmitt trigger, 47 kΩ pull-down to ground 33 to 4,000 reads/writes per second typ, system dependent Schmitt trigger hysteresis 1.01 V typ 0.6 V min 1.5 V max 2.43 V typ 1.9 V min 3.1 V max 1.42 V typ 1.0 V min 2.0 V max 5.5 V absolute max –0.
USB-202 User's Guide Specifications USB specifications Table 11. USB specifications Parameter Specification USB device type Device compatibility USB cable type USB 2.0 (full-speed) USB 1.1, USB 2.0 A-B cable, UL type AWM 2725 or equivalent. (minimum 24 AWG VBUS/GND, minimum 28 AWG D+/D–) 3 m (9.84 ft) max USB cable length Environmental Table 12.
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Measurement Computing Corporation 10 Commerce Way Suite 1008 Norton, Massachusetts 02766 (508) 946-5100 Fax: (508) 946-9500 E-mail: info@mccdaq.com www.mccdaq.
