USB-234-OEM
Analog and Digital I/O

User's Guide

January 2019. Rev 4© Measurement Computing Corporation

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Measurement Computing Corporation, InstaCal, Universal Library, and the Measurement Computing logo areeither trademarks or registered trademarks of Measurement Computing Corporation. Refer to the Copyrights &Trademarks section on mccdaq.com/legal for more information about Measurement Computing trademarks.
Other product and company names mentioned herein are trademarks or trade names of their respective
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© 2019 Measurement Computing Corporation. All rights reserved. No part of this publication may be
reproduced, stored in a retrieval system, or transmitted, in any form by any means, electronic, mechanical, by
photocopying, recording, or otherwise without the prior written permission of Measurement Computing
Corporation.
NoticeMeasurement Computing Corporation does not authorize any Measurement Computing Corporation product for
use in life support systems and/or devices without prior written consent from Measurement Computing
Corporation. Life support devices/systems are devices or systems that, a) are intended for surgical implantation
into the body, or b) support or sustain life and whose failure to perform can be reasonably expected to result ininjury. 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 ofpeople.

HM USB-234-OEM.docx

2

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 ......................................................................................................................... 5
Where to find more information ......................................................................................................................... 5
Chapter 1

Introducing the USB-234-OEM ............................................................................................................. 6
Functional block diagram ................................................................................................................................... 7
Chapter 2

Installing the USB-234-OEM ................................................................................................................. 8
Unpacking........................................................................................................................................................... 8
Installing the software ........................................................................................................................................ 8
Installing the hardware ....................................................................................................................................... 8
Installing on a Windows platform ..................................................................................................................................... 8
Installing on an Android platform ..................................................................................................................................... 8

Calibrating the hardware..................................................................................................................................... 8
Chapter 3

Functional Details ................................................................................................................................. 9
Analog input acquisition modes ......................................................................................................................... 9
Software paced mode ........................................................................................................................................................ 9
Hardware paced mode....................................................................................................................................................... 9

Board components ............................................................................................................................................ 10
USB connector .................................................................................................................................................................10
Header connector J2.........................................................................................................................................................10Signal connections ............................................................................................................................................ 11
Analog input ....................................................................................................................................................................11
Analog output ..................................................................................................................................................................13
Digital I/O ........................................................................................................................................................................15
Trigger input ....................................................................................................................................................................16
Counter input ...................................................................................................................................................................16
USB signals, power (D–, D+, VBUS)..............................................................................................................................16
Status LED driver (LED) .................................................................................................................................................16+VO power source ...........................................................................................................................................................17
Ground .............................................................................................................................................................................18

Mechanical drawings ........................................................................................................................................ 19
Chapter 4

Specifications ...................................................................................................................................... 20
Analog input ..................................................................................................................................................... 20
Absolute accuracy (analog input DC voltage measurement accuracy) ............................................................................20

Analog output ................................................................................................................................................... 21
Timebase........................................................................................................................................................... 21
Digital input/output........................................................................................................................................... 21
Digital input .....................................................................................................................................................................22
Digital output ...................................................................................................................................................................22

External digital trigger ...................................................................................................................................... 22
Counter ............................................................................................................................................................. 22
LED electrical characteristics ........................................................................................................................... 23
Memory ............................................................................................................................................................ 23
Power requirements .......................................................................................................................................... 233

USB-234-OEM User's Guide

Power output ..................................................................................................................................................... 23
USB specifications ........................................................................................................................................... 23
Environmental .................................................................................................................................................. 24
Mechanical ....................................................................................................................................................... 24
Header connectors ............................................................................................................................................ 24
Differential mode pinout ..................................................................................................................................................24
Single-ended mode pinout ...............................................................................................................................................25

4

Preface

About this User's Guide
What you will learn from this user's guideThis user's guide describes the Measurement Computing USB-234-OEM 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.
bold text

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

italic text

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

Where to find more information
Additional information about USB-234-OEM hardware is available on our website at www.mccdaq.com. You
can also contact Measurement Computing Corporation with specific questions.


Knowledgebase: kb.mccdaq.com
Tech support form: www.mccdaq.com/support/support_form.aspx
Email: techsupport@mccdaq.com
Phone: 508-946-5100 and follow the instructions for reaching Tech Support

For international customers, contact your local distributor. Refer to the International Distributors section on our
website at www.mccdaq.com/International.

5Chapter 1

Introducing the USB-234-OEM
The USB-234-OEM is a USB 2.0 high-speed data acquisition board that provides the following features:









Eight single-ended (SE) or four differential (DIFF) 16-bit analog inputs
100 kS/s maximum sample rate
Two analog outputs with 5 kS/s simultaneous update rate per channel maximum
Eight individually configurable digital I/O channels
32-bit counter
Digital trigger input
User voltage output
One 34-pin header connector for field wiring connections

The USB-234-OEM is a USB 2.0 high speed device that is compatible with USB 3.0 ports. The device is also
compatible with USB 1.1 ports, but use with this older hardware is not recommended due to longer initialization
times that can occur when the USB-234-OEM is connected through USB 1.1 ports or hubs.
The USB-234-OEM is powered by the +5 V USB supply from your computer; no external power is required.
Caution! There are no product safety, electromagnetic compatibility (EMC), or CE marking complianceclaims made for the USB-234-OEM. The USB-234-OEM is intended for use as a component of alarger system. MCC can help developers meet their compliance requirements. The end productsupplier, however, is responsible for conforming to any and all compliance requirements.

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USB-234-OEM User's Guide

Introducing the USB-234-OEM

Functional block diagram
Device functions are illustrated in the block diagram shown here.

Figure 1. USB-234-OEM functional block diagram

7

Chapter 2

Installing the USB-234-OEM
UnpackingAs with any electronic device, you should take care while handling to avoid damage from static
electricity. Before removing the board 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.

Installing the software
Refer to the USB-234-OEM product page on the Measurement Computing website for information about how
to install the supported software.
Install the software before you install the hardware
The driver needed to run the device is installed when you install the software. Therefore, you need to install thesoftware package you plan to use before you install the hardware.

Installing the hardware
Installing on a Windows platform
Connect the USB-234-OEM to a to an available USB port on the computer running Windows. Connect theother end of the cable to the micro-USB connector on the device. No external power is required.
When connected for the first time, a Found New Hardware dialog opens when the operating system detects thedevice. When the dialog closes, the installation is complete.

Installing on an Android platform
Many Android devices include a standard A-type USB port to connect to the USB-234-OEM. If your device
does not have a USB port, you may need a USB OTG cable for your Android device to host a USB device.
Refer to your Android device documentation for more information.

Calibrating the hardware
The Measurement Computing Manufacturing Test department performs the initial factory calibration. Returnthe device to Measurement Computing Corporation when calibration is required. The recommended calibrationinterval is one year.
Field calibration is not supported.

8

Chapter 3

Functional Details
Analog input acquisition modes
The USB-234-OEM 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 asoftware command. The analog value is converted to digital and returned to the computer. You can repeat thisprocedure until you have the total number of samples that you want.
The maximum throughput sample rate in software paced mode is system-dependent.

Hardware paced mode
You can acquire data from up to eight channels in hardware paced mode. The analog data is continuously
acquired and converted to digital values until you stop the scan. Data is transferred in blocks of samples fromthe device to the memory buffer on your computer. The block size varies depending on the sample rate.
The maximum continuous scan rate is an aggregate rate. The total acquisition rate for all channels cannot
exceed 100 kS/s. The following table lists the scan rate when scanning from one to eight channels.
Maximum continuous scan rate
# channels
scannedSample rate
(kS/s)

1
2
3
4
5
6
7
8

100
50
33.33
25
20
16.67
14.29
12.5

You can start a hardware paced continuous scan with either a software command or with an external hardware
trigger event.

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USB-234-OEM User's Guide

Functional Details

Board components
Board components are shown in Figure 2.

1

Micro-USB connector

234-pin header connector (J2)

Figure 2. Board components

USB connector
The Micro-USB connector provides +5 V power and communication. No external power supply is required.
When using the USB connector to connect to the USB host, leave the D+ and D- signals and VBUS on the
34-pin connector disconnected.

Header connector J2
The 34-pin header connector provides the connections listed in the following pinout tables.
Caution! To ensure the specified EMC performance, the length of any wire or cable connected to the header
connector must be no longer than 0.5 m (20 in.).
Differential mode pinout
Do not connect to connector pins labeled NC.
J2 differential pinout
Pin
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33

Signal name
AOUT0
AGND
CH3H
CH2H
CH1H
CH0H
AGND
D–
D+
GND
DIO1
DIO3
DIO5
DIO7
TRIG
NC
CTR

Pin description
Analog output 0
Analog ground
Analog input 3 HI
Analog input 2 HI
Analog input 1 HI
Analog input 0 HI
Analog groundUSB differential data signals
USB differential data signals
Digital ground
DIO bit 1
DIO bit 3
DIO bit 5
DIO bit 7
Digital trigger input
No connection
Counter input

Pin
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34

10

Signal name
AOUT1
AGND
CH3L
CH2L
CH1L
CH0L
AGND
VBUS
LED
DIO0
DIO2
DIO4
DIO6
NC
NC
GND
+VO

Pin description
Analog output 1
Analog ground
Analog input 3 LO
Analog input 2 LO
Analog input 1 LO
Analog input 0 LO
Analog groundUSB power
Status LED driver
DIO bit 0
DIO bit 2
DIO bit 4
DIO bit 6
No connection
No connection
Digital ground
User voltage output

USB-234-OEM User's Guide

Functional Details

Single-ended mode pinout
Do not connect to connector pins labeled NC.
J2 single-ended pinout
Pin
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33

Signal name
AOUT0
AGND
CH3H
CH2H
CH1H
CH0H
AGND
D–
D+
GND
DIO1
DIO3
DIO5
DIO7
TRIG
NC
CTR

Pin description
Analog output 0
Analog ground
Analog input 3
Analog input 2
Analog input 1
Analog input 0
Analog groundUSB differential data signals
USB differential data signals
Digital ground
DIO bit 1
DIO bit 3
DIO bit 5
DIO bit 7
Digital trigger input
No connection
Counter input

Pin
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34

Signal name
AOUT1
AGND
CH3L
CH2L
CH1L
CH0L
AGND
VBUS
LED
DIO0
DIO2
DIO4
DIO6
NC
NC
GND
+VO

Pin description
Analog output 1
Analog ground
Analog input 7
Analog input 6
Analog input 5
Analog input 4
Analog groundUSB power
Status LED driver
DIO bit 0
DIO bit 2
DIO bit 4
DIO bit 6
No connection
No connection
Digital ground
User voltage output

Signal connections
Analog input
You can connect up to eight single-ended inputs or up to four differential inputs to connectors CH0H/CH0L
through CH3H/CH3L. The input voltage range is ±10 V. Figure 3 shows the USB-234-OEM analog input
circuitry.

Figure 3. USB-234-OEM analog input circuitry

The main analog input circuitry blocks are as follows:

MUX—The multiplexer (MUX) routes one AI channel at a time to the mode selector multiplexerDIFF/SE MUX—The mode selector MUX selects between DIFF mode and SE measurement mode.
IA— The instrumentation amplifier (IA) removes the common mode signal and buffers the analog input(DIFF/SE MUX).

signal before it is sampled by the analog-to-digital converter (ADC).
ADC—The ADC digitizes the AI signal by converting the analog voltage into digital code.
11USB-234-OEM User's Guide

Functional Details

AI FIFO—The DAQ device can perform both single and multiple analog-to-digital conversions of a fixed orinfinite number of samples. A first-in-first-out (FIFO) buffer holds data during AI acquisitions to ensure nodata is lost.
ADC Control—The ADC control circuitry sets the conversion rate of the ADC, sets the input
configuration, drives the scanning sequence, and starts acquisitions synchronous with the TRIG or CTR
signalSingle-ended configuration
When configured for SE input mode, the input signal is referenced to analog ground (AGND) and delivered
through two wires:

Connect the wire carrying the signal to be measured (CHxH or CHxL).
Connect the second wire to AGND.

The input range for single-ended mode is ±10 V. The single-ended mode pinout is shown in the Single-ended
mode pinout section on page 11.
Differential configuration
When configured for differential input mode, the input signal is measured with respect to the low input anddelivered through three wires:Connect the wire carrying the signal to be measured to CHxH
Connect the wire carrying the reference signal to CHxL
Connect the third wire to AGND.

The differential mode pinout is shown in the Differential mode pinout section on page 10.
Note: To perform a single-ended measurement using differential channels, connect the signal to CHxH andground the associated CHxL input.

Input range
The USB-234-OEM has an input range of ±10 V. For DIFF mode, each AI should stay within ±10 V withrespect to AGND, and the voltage between positive and negative inputs should be lower or equal to ±10 V. For
SE mode, signals of ±10 V at any analog input connector with respect to AGND are accurately measured.
Beyond ±10 V, the input signal begins clipping as shown in Figure 4. Typically, this clipping begins at ±10.5 V.

Figure 4. Analog input exceeding ±10 V returning clipped results

12USB-234-OEM User's Guide

Functional Details

Multichannel scanning
The USB-234-OEM can scan multiple channels at high rates and digitize the signals accurately. However, you
should consider several issues when designing your measurement system to ensure the high accuracy of yourmeasurements:Use low impedance sources – To ensure fast settling times, your signal sources should have an
impedance of <1 kΩ. Large source impedances increase the settling time of the DAQ device and decrease
the accuracy at fast scanning rates.
Use short high-quality cabling – Using short high-quality cables can minimize several effects that
degrade accuracy including crosstalk, transmission line effects, and noise. The capacitance of the cable also
can increase the settling time.
To ensure the specified EMC performance, operate this product only with shielded cables and accessories.
The length of any wire or cable connected to the connector must be no longer than 0.5 m (20 in.).
Avoid scanning faster than necessary – Design your system to scan at slower speeds to give the DAQ
device more time to settle to a more accurate level when switching between channels.

Analog output
Figure 5 shows the USB-234-OEM analog output circuitry.

Figure 5. USB-234-OEM analog output circuitry

The main analog output circuitry blocks are as follows:






Protection – The protection circuit prevents damage of the buffers in case of a short circuit or an
overvoltage condition.
Buffer – The buffer amplifies the analog signal to the ±10 V range and ensures the driving capability forthe external load.
DAC 0 and DAC 1 – The digital-to-analog converters (DAC) convert the digital signals into low-levelanalog signals.
AO FIFO – The AO FIFO (first-in-first out) ensures that data is transferred to the DACs in a timely mannerwithout being affected by USB latencies.
DAC Control – The DAC control sets the DAC data rate and the startup condition, which could betriggered by the TRIG signal.

Analog output signals are referenced to AGND. Connect the loads between AOUT0 or AOUT1 and AGND as
shown in Figure 6 on page 14.

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USB-234-OEM User's Guide

Functional Details

Figure 6. USB-234-OEM analog output connection diagram

Power-on state
The AO circuitry exhibits a short glitch when the device is powered on and when the DAQ device exits suspend
mode. After power-up, the AO circuitry is reset to 0 V.
AO range
The AO range is ± 10 V.
Minimizing glitches on the output signal
When using a DAC to generate a waveform, you may observe glitches on the output signal. These glitches arenormal; when a DAC switches from one voltage to another, it produces glitches due to released charges. The
largest glitches occur when the most significant bit of the DAC code changes. You can build a low-passdeglitching filter to remove some of these glitches, depending on the frequency and nature of the output signal.
Generating analog output data
The USB-234-OEM can generate analog output data in two different modes – software paced and hardware
paced.


Software paced – Software controls the rate at which data is generated. Software sends a separate
command to the hardware to initiate each DAQ conversion. Software-paced generations are also referred toas immediate or static operations. They are typically used for writing a single value out, such as a constantDC voltage.
Hardware paced – A digital hardware signal controls the generation rate. This signal is generated
internally on your device. Hardware-paced generations have advantages over software-timed acquisitions,such as the time between samples can be much shorter, and the timing between samples can be
deterministic (data is sampled at regular intervals).

Hardware-timed operations are buffered. During hardware-paced AO generation, data is moved from a PC
buffer to the onboard FIFO on the DAQ device using USB signal streams before it is written to the DACs one
sample at a time. Buffered generations allow for fast transfer rates because data is moved in large blocks rather
than one point at a time.
The sample mode can be either finite or continuous in a buffered I/O operation:

In finite sample mode, a specified number of samples are generated, and then the generation stops.
In continuous mode, an unspecified number of samples are generated until you stop the generation.

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USB-234-OEM User's Guide

Functional Details

Digital I/O
You can connect up to eight digital I/O lines to DIO0 through DIO7. GND is the ground-reference signal for
digital I/O. Each digital I/O line is bit-configurable as input or output. Digital input voltage ranges from 0 V to5 V are permitted, with thresholds of 0.8 V (low) and 2.3 V (high). Each DIO channel can sink up to 4 mA for
direct drive applications when used as an output. All digital I/O updates and samples are software-paced.
Figure 7 below shows DIO0 through DIO7connected to signals configured as digital inputs and digital outputs.

1
2
3

DIO0 configured as an open drain digital output driving a LED
DIO4 configured as a digital input receiving a TTL signal from a gated inverter
DIO7 configured as an digital input receiving a 0 V or 5 V signal from a switch

Figure 7. Example of connecting a load

Caution! Exceeding the maximum input voltage ratings or maximum output ratings – listed in theSpecifications chapter – can damage the device and the computer. Measurement Computing is notliable for any damage resulting from such signal connections.
Power-on states
At system startup and reset, the USB-234-OEM sets all DIO lines to high-impedance inputs. The device does
not drive the signal high or low. Each line has a weak pull-down resistor connected to it.
DIO protection
To protect the DAQ device against overvoltage, undervoltage, and overcurrent conditions, as well as ESD
events, avoid these fault conditions by using the following guidelines:If you configure a DIO line as an output, do not connect it to any external signal source, ground signal, or
power supply.
If you configure a DIO line as an output, understand the current requirements of the load connected to thesesignals. Do not exceed the specified current output limits of the DAQ device. Measurement Computing has
several signal conditioning solutions for digital applications requiring high-current drive.
If you configure a DIO line as an input, do not drive the line with voltages outside of its normal operating
range. The DIO lines have a smaller operating range than the AI signals.
Treat the DAQ device as you would treat any static-sensitive device. Always properly ground yourself andthe equipment when handling the DAQ device or connecting to it.
15USB-234-OEM User's Guide

Functional Details

Trigger input
The TRIG connector is an external digital trigger input. The trigger mode is software-selectable for rising edgeor falling edge detection.

Counter input
The CTR connector is a 32-bit counter that can count rising edges. Edges can only be counted up from 0.
Counting down is not supported – you cannot set the initial count to 100 and count down to 99, 98, 97.

USB signals, power (D–, D+, VBUS)
When using a USB connector on your motherboard to connect the USB-234-OEM to the USB host through the34-pin connector, do not connect to the USB connector.

Status LED driver (LED)The LED signal indicates the device status as shown in the following table:
LED State

Device StatusOffOn, not blinking
Blinking

Device is not connected or is in suspend mode.
Device is connected and functioning normally.
Device has encountered an error.

An open collector output drives the LED signal. For applications that use the LED signal, connect an external
pull-up resistor from the LED signal to an external voltage.
LED electrical characteristics are listed in the Specifications chapter.
To drive a status LED, refer to the circuit in Figure 8.

Figure 8. Circuit to drive a status LED

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USB-234-OEM User's Guide

Functional Details

To use the LED signal to monitor the device state, refer to the circuit in Figure 9.

Figure 9. Circuit to monitor device state with LED signal+VO power source
Figure 10 shows the +VO power source circuitry of the USB-234-OEM.

Figure 10. +VO power source circuitry

The main blocks featured in the +VO power source circuitry are as follows:+5 V Source—Regulated 5 V supply.
+5 V Protection—Circuit for overvoltage, over current, and short circuit protection.

The +5 V source is limited at 200 mA typically. In case of hard short circuit to ground, this limit is further
reduced to avoid excessive power dissipation.
Connecting the load
The return connector for the +5 V source is the GND connector. The +5 V load should be connected between
the +VO connector and GND. The current delivered by the USB-234-OEM at the +VO connector is sourced
from the USB connector. To meet the USB specifications, a maximum of 150 mA can be used from the +VO
connector.

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USB-234-OEM User's Guide

Functional Details

Figure 11. Connecting the +VO power source load

The + 5 V power is always enabled and the voltage is present at the +VO connector when the device is in active
mode. The +5 V power source is not available for about one second after the device is first connected to the
USB connector or when the device is in suspend mode.

GroundThe analog ground (AGND) connectors provide a common ground for all analog channels. The digital ground(GND) connectors provide a common ground for the digital, counter, and power connector.
For more information about signal connections
For more information about analog and digital signal connections, refer to the Guide to DAQ Signal
Connections on our website at www.mccdaq.com/support/DAQ-Signal-Connections.aspx.

18USB-234-OEM User's Guide

Functional Details

Mechanical drawings

Figure 12. Circuit board dimensions

19

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. Analog input specifications
Parameter

Condition

Specification

A/D converter type

Successive approximation

ADC resolution

16 bits

Sampling rate

Maximum aggregate

100 kS/s

Number of channels

8 single-ended or 4 differential; software-selectable

Input voltage range
Working voltage

Input impedance

±10 V
±10 V
±30 V max
±20 V max
>1 GΩInput bias current
INL
DNL±200 pA, typ±1.8 LSB
16 bits no missing codes

CMRR

56 dB (DC to 5 kHz)

Input bandwidth
Trigger sources

300 kHz
Software, TRIG

Power onPower off

Overvoltage protection

Absolute accuracy (analog input DC voltage measurement accuracy)
Table 2. Absolute accuracy (no load)
Range

At full scale (typical at 25 °C)

At full scale (maximum over temperature)

System noise

±10 V

6 mV

26 mV

0.4 mVrms

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USB-234-OEM User's Guide

Specifications

Analog output
Table 3. Analog output specifications
Parameter
Resolution
Output range
Number of channels
Update rate
Trigger sources
Output current drive

Condition

Specification
16 bits, 1 in 65,536±10 V
2
5 kS/s simultaneous per channel max, hardware-paced
Software, TRIG
±5 mA

Hardware paced

Short circuit current±11 mA

Slew rate
Output impedance

3 V/µs0.2 ΩAbsolute accuracy (no load)

Typical at full scale

8.6 mV

Maximum over temperature,
full scale

32 mV

INL
DNL
Power-on state
Startup glitch±4 LSB
16 bits no missing codes
0V–7 V for 10 µs

Timebase
The following specifications apply to hardware-paced analog input and analog output sampling accuracy.
Parameter

Specification

Timebase frequency
Timebase accuracy

80 MHz±100 ppm

Timing resolution

12.5 ns

Digital input/output
Table 4. Digital I/O specifications
Parameter

Specification

Compatibility
Number of channels
Configuration
Pull-down resistor
Absolute maximum voltage
range

LVTTL, 3.3 V LVCMOS
8 (DIO0 through DIO7)
Each bit can be configured as input (power on default) or output
47.5 kΩ to digital ground (GND).
–0.3 V to 5 V with respect to digital ground (GND)21

USB-234-OEM User's Guide

Specifications

Digital input
Table 5. Digital input specifications
Parameter

Condition

Specification

Input voltage range

Power onPower off

0 V to 5 V
0 V to 3.3 V (Note 1)±20 V on two lines per port (maximum of fivelines for all ports) for up to 24 hours
2.3 V min
0.8 V max
0.8 mA max
4.5 mA max

Input voltage protection
Input high voltage
Input low voltage
Input leakage current

At 3.3 V
At 5 V

Note 1: Do not leave a voltage above 3.3 V connected on the DIO line when the device is not powered. This can cause
long-term reliability issues.

Digital output
Table 6. Digital output specifications
Parameter

Condition

Specification

Output low voltage

4 mA
1 mA
4 mA
1 mA

0.7 V max
0.2 V max
2.1 V min
2.8 V min
3.6 V max
±4 mA

Output high voltage

Maximum output current perline

External digital trigger
Table 6. External digital trigger specifications
Parameter

Specification

Trigger source
Trigger mode
Input high voltage
Input low voltage

TRIG input
Software configurable for rising or falling edge. Power on default is rising edge.
2.3 V min
0.8 V max

CounterTable 7. Counter specifications
Parameter

Specification

Pin name
Number of counters
Resolution
Counter typeCounter direction
Counter source
Input frequency
High pulse width
Low pulse width

CTR1
32 bits
Edge counter (rising)Count up
CTR
5 MHz max
100 ns min
100 ns min22

USB-234-OEM User's Guide

Specifications

LED electrical characteristics
Table 8. LED electrical specifications
Parameter

Condition

Specification

Output Low Voltage

IOL = 8 mA
IOL = 18 mA

0.4 V max
1.2 V typ5.25 V max
18 mA maxExternal pull-up voltage
Maximum sinking current

MemoryTable 9 Memory specifications
Parameter

Specification

Data FIFO

2,047 samples (4096 bytes)

Non-volatile memoryUp to 256 kB microcontroller integrated Flash
2 kB microcontroller integrated EEPROM)

Power requirements
Table 10. Power specifications
Parameter

Specification

From USB
Idle USB current

4.50 to 5.25 VDC (Note 2)
165 mA

Maximum load USB current<500 mA (Note 3)

Note 2: A typical bus-powered hub provides 100 mA on its USB lines. The USB-234-OEM does not work on a buspowered hub.
Note 3: The maximum power draw from all output terminals should be kept under 0.9 W to avoid overloading the USB
portPower output
Table 11. External voltage specifications
Parameter

Specification

Output voltage

5 V, ±3%

Maximum current
Overcurrent protection
Short circuit current
Overvoltage protection

150 mA
200 mA
50 mA±20 V

USB specifications
Table 12. USB specifications
Parameter

Specification

Device type
Device compatibility
Connector type
USB cable type

USB 2.0 full speed (12 Mb/s)
USB 1.1, USB 2.0
USB micro-B receptacle
A-micro-B cable, UL type AWM 2725 or equivalent (28 AWG × 2C + 28 AWG × 2C +AB)
3 m (9.84 ft) max

USB cable length23

USB-234-OEM User's Guide

Specifications

Environmental
Table 13. Environmental specifications (Indoor use only)
Parameter

Specification

Operating temperature range
Storage temperature range
Operating humidity range
Storage humidity range
Pollution degree (IEC 60664)
Maximum altitude

0 °C to 45 C
–40 °C to 85 °C
5% to 95% RH, non-condensing
5% to 90% RH, non-condensing
2
2,000 mMechanical
Table 14. Mechanical specifications
Parameter

Specification

Dimensions (L × W × H)

98 mm × 64 mm × 12 mm (3.90 in. × 2.50 in. × 0.50 in.)

Weight31 g (1.10 oz)

Header connectors
Table 15. Header connector specifications
Parameter

Specification

Connector type

One 2 × 17 0.1 in. pitch headers labeled J2

Differential mode pinout
Do not connect to connector pins labeled NC.
Table 16. J2 differential pinout
Pin
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33

Signal name
AOUT0
AGND
CH3H
CH2H
CH1H
CH0H
AGND
D–
D+
GND
DIO1
DIO3
DIO5
DIO7
TRIG
NC
CTR

Pin description
Analog output 0
Analog ground
Analog input 3 HI
Analog input 2 HI
Analog input 1 HI
Analog input 0 HI
Analog groundUSB differential data signals
USB differential data signals
Digital ground
DIO bit 1
DIO bit 3
DIO bit 5
DIO bit 7
Digital trigger input
No connection
Counter input

Pin
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34

24

Signal name
AOUT1
AGND
CH3L
CH2L
CH1L
CH0L
AGND
VBUS
LED
DIO0
DIO2
DIO4
DIO6
NC
NC
GND
+VO

Pin description
Analog output 1
Analog ground
Analog input 3 LO
Analog input 2 LO
Analog input 1 LO
Analog input 0 LO
Analog groundUSB power
Status LED driver
DIO bit 0
DIO bit 2
DIO bit 4
DIO bit 6
No connection
No connection
Digital ground
User voltage output

USB-234-OEM User's Guide

Specifications

Single-ended mode pinout
Do not connect to connector pins labeled NC.
Table 17. J2 single-ended pinout
Pin
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33

Signal name
AOUT0
AGND
CH3H
CH2H
CH1H
CH0H
AGND
D–
D+
GND
DIO1
DIO3
DIO5
DIO7
TRIG
NC
CTR

Pin description
Analog output 0
Analog ground
Analog input 3
Analog input 2
Analog input 1
Analog input 0
Analog groundUSB differential data signals
USB differential data signals
Digital ground
DIO bit 1
DIO bit 3
DIO bit 5
DIO bit 7
Digital trigger input
No connection
Counter input

Pin
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34

25

Signal name
AOUT1
AGND
CH3L
CH2L
CH1L
CH0L
AGND
VBUS
LED
DIO0
DIO2
DIO4
DIO6
NC
NC
GND
+VO

Pin description
Analog output 1
Analog ground
Analog input 7
Analog input 6
Analog input 5
Analog input 4
Analog groundUSB power
Status LED driver
DIO bit 0
DIO bit 2
DIO bit 4
DIO bit 6
No connection
No connection
Digital ground
User voltage output

Measurement Computing Corporation
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