USB-DIO24/37
24-Channel Digital I/O USB Device

User's GuideMay 2019. Rev 4© Measurement Computing Corporation

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HM USB-DIO24_37.docx

Table of Contents
Preface

About this User's Guide ....................................................................................................................... 4
What you will learn from this user's guide ......................................................................................................... 4
Conventions in this user's guide ......................................................................................................................... 4
Where to find more information ......................................................................................................................... 4
Chapter 1

Introducing the USB-DIO24/37 ............................................................................................................. 5
Overview: USB-DIO24/37 features.................................................................................................................... 5
Functional block diagram ................................................................................................................................... 5
Chapter 2

Installing the USB-DIO24/37 ................................................................................................................. 6Unpacking........................................................................................................................................................... 6
Installing the software ........................................................................................................................................ 6
Installing the hardware ....................................................................................................................................... 6
Connecting the board for I/O operations ............................................................................................................ 6
Connectors and cables....................................................................................................................................................... 6
Field wiring, signal termination and conditioning ............................................................................................................ 7

Chapter 3

Functional Details ................................................................................................................................. 8Components ........................................................................................................................................................ 8
37-pin I/O connector ......................................................................................................................................................... 8
USB connector .................................................................................................................................................................. 9LED .................................................................................................................................................................................. 9
Pull-up resistors ................................................................................................................................................................ 9Power consumption ............................................................................................................................................ 9
Mechanical Drawings ....................................................................................................................................... 10
Chapter 4

Specifications ...................................................................................................................................... 11
Digital input/output........................................................................................................................................... 11Counter ............................................................................................................................................................. 11
Data transfer rates ............................................................................................................................................. 12Power ................................................................................................................................................................ 12
General ............................................................................................................................................................. 12
Environmental .................................................................................................................................................. 12
Mechanical ....................................................................................................................................................... 13
Main connector and pinout ............................................................................................................................... 13Declaration of Conformity .................................................................................................................. 143

Preface

About this User's Guide
What you will learn from this user's guideThis user's guide explains how to install, configure and use the USB-DIO24/37 digital I/O board. This user'sguide 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
Text presented in a box signifies additional information and helpful hints related to the subject matter you arereading.
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 the 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-201 hardware is available on our website at www.mccdaq.com. You canalso 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 ourwebsite at www.mccdaq.com/International.

4Chapter 1

Introducing the USB-DIO24/37
Overview: USB-DIO24/37 features
This manual explains how to install, configure and use the USB-DIO24/37 digital I/O board. You can use thisboard in a variety of digital applications to control logic devices such as switches, gauges, relays, pumps, andsensors.
The USB-DIO24/37 is a USB 2.0 low-speed device supported under popular Microsoft® Windows® operatingsystems. It is designed for USB 1.1 ports and is fully compatible with both USB 1.1 and USB 2.0 ports.
The USB-DIO24/37 features 24 bits of digital I/O and one 32-bit external event counter. The device is poweredby the +5 volt USB supply. No external power is required. All I/O connections are made to a 37-pin connector.
Digital channels are pulled up to +5V with 47 kΩ resistors.
An on-board industry standard 82C55 programmable peripheral interface chip provides the 24 discrete digital
I/O lines in four ports. You configure each digital port independently for either input or output.
The USB-DIO24/37 board is completely plug-and-play, with no jumpers or switches to set. All board addresses
are set by the system's plug-and-play software.

Functional block diagram
USB-DIO24/37 functions are illustrated in the block diagram shown here.

Figure 1. USB-DIO24/37 functional block diagram

5Chapter 2

Installing the USB-DIO24/37
UnpackingAs with any electronic device, you should take care while handling to avoid damage from staticelectricity. 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.

Installing the software
Refer to the MCC DAQ Quick Start and the USB-DIO24/37 product page on our website for information about
the software supported by the USB-DIO24/37.
Install the software before you install your device
The driver needed to run the USB-DIO24/37 is installed with the software. Therefore, you need to install thesoftware package you plan to use before you install the hardware.

Installing the hardware
To connect the USB-DIO24/37 to the system, connect the USB cable to an available USB port on the computeror to an external USB hub connected to the computer.
When you connect the USB-DIO24/37 for the first time, multiple Found New Hardware popup balloons open
when the operating system detects the device. When installation is complete, the USB LED should flash andthen remain on. This indicates that communication is established between the USB-DIO24/37 and yourcomputer.
If the USB LED turns off
If the USB LED is on but then turns off, the computer has lost communication with the USB-DIO24/37. To
restore communication, disconnect the USB cable from the computer, and then reconnect it. This should restore
communication, and the USB LED should turn back on.
Caution! Do not disconnect any device from the USB bus while the computer is communicating with theUSB-DIO24/37, or you may lose data and/or your ability to communicate with theUSB-DIO24/37.

Connecting the board for I/O operations
Connectors and cables
The table below lists the board I/O connector type and compatible cables for use with the USB-DIO24/37.
Board connectors, cables, and accessory equipment
Connector typeCompatible cables

37-pin D-type connector
C37FF-x unshielded ribbon cable. x = length in feet6USB-DIO24/37 User's Guide

Installing the USB-DIO24/37

Figure 2. Connector pinout

Information on signal connections
General information regarding signal connection and configuration is available in the Guide to DAQ Signal
Connections (available for download from www.mccdaq.com/support/DAQ-Signal-Connections.aspx.)

The red stripe
identifies pin # 111202037191937

Figure 3. C37FF-x cable

Field wiring, signal termination and conditioning
Refer to the product page at www.mccdaq.com/usb-data-acquisition/USB-DIO24-Series.aspx for compatible
products to use with the USB-DIO24/37.

7

Chapter 3

Functional Details
Components
The USB-DIO24/37 has the following components, as shown in Figure 5.


37-pin I/O connector
USB connector
LEDFigure 4. USB-DIO24/37 components

37-pin I/O connector
The 37-pin connector provides 24 digital I/O, one counter, six ground, and two 5V power connections.
The digital I/O is configured as two 8-bit and two 4-bit ports based on the 82C55 specification. Configure
each port independently for input (default) or output.
The CTR signal is the input to the 32-bit external event counter. The internal counter increments when thedigital input level transitions from low to high and can count frequencies of up to 1 MHz.
The six ground (GND) connections are identical and provide a common ground for all device functions.
The two power connections draw power from the USB connector. The +5 pin is a +5 volt output that issupplied by the computer.

Caution! The +5 V pin is an output. Do not connect to an external power supply or you may damage theUSB-DIO24/37 and possibly the computer8

USB-DIO24/37 User's GuideFunctional Details

USB connector
The USB 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.

LEDThe LED indicates the communication status of the USB-DIO24/37. It uses up to 5 mA of current and cannot bedisabled. The table below explains the function of the USB-DIO24/37 LED.
LED Illumination
LED status

Description

Steady green
Blinks continuously
Blinks three times

The USB-DIO24/37 is connected to a computer or external USB hub.
Data is being transferred.
Initial communication is established between the USB-DIO24/37 and the computer.

Pull-up resistors
Each digital port has an internal 47 kΩ pull-up resistor network. All digital pins are pulled up to +5 V (highlogic level) on power up and reset.

Power consumption
The maximum total output current that can be drawn from all USB-DIO24/37 connections (power and digitaloutputs) 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.
Once you start running applications with the USB-DIO24/37, each DIO bit can draw up to 2.5 mA. Themaximum amount of +5V current available for external use, over and above that required by the USBDIO24/37, is the difference between the total current requirement of the USB-DIO24/37 (based on theapplication), and the allowed current draw of the PC platform (500 mA for desktop PCs and self-powered hubs,or 100 mA for bus-powered hubs and notebook computers).
With all outputs at their maximum output current, you can calculate the total current requirement of the USBDIO24/37 +5 V as follows:(USB-DIO24/37 @ 40 mA) + (24 DIO @ 2.5 mA ea) = 100 mA

For an application running on a PC or powered hub, this value yields a maximum user current of
500 mA−100 mA = 400 mA. This number is the total maximum available current at the +5 output pins.
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 320 mA.
Since laptop computers typically allow up to 100 mA, the USB-DIO24/37 in a fully-loaded configuration may
be above that allowed by the computer. In this case, you must determine the per-pin loading in the application
to ensure that the maximum loading criteria is met. The per-pin loading is calculated by simply dividing the+5 V by the load impedance of the pin in question.

9USB-DIO24/37 User's Guide

Functional Details

Mechanical Drawings

Figure 5. Circuit board dimensions

10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.

Digital input/output
Table 1. Digital I/O specifications
ParameterSpecification

Digital type
Number of I/O
Configuration
Pull up/pull-down configuration

82C55
24 (Port A Bit 0 through Port C Bit7)
2 banks of 8 and 2 banks of 4, or 3 banks of 8
All pins pulled up to Vs via 47 kΩ resistors (default). Selection available forpull down to ground. Hardware selectable via zero Ω resistor.

Input high voltage
Input low voltage
Output high voltage (IOH = –2.5 mA)
Output low voltage (IOH = –2.5mA)
Power up / reset state

2.0 V min, 5.5 V absolute max
0.8 V max, –0.5 V absolute min
3.0 V min
0.4V max
Input mode

CounterTable 2. Counter specifications
Parameter

Specification

Pin name (Note 1)
Counter type

CTR
Event counter

Number of channels

1

Input type

TTL, rising edge triggered

Input source
Resolution
Schmidt trigger hysteresis
Input leakage current
Maximum input frequency
High pulse width
Low pulse width
Input low voltage

CTR screw terminal
32 bits
20 mV to 100 mV
±1 µA
1 MHz
500 ns min
500 ns min
0 V min, 1.0 V max

Input high voltage

4.0 V min, 15.0 V max

Note 1:

CTR is a Schmitt trigger input

11USB-DIO24/37 User's Guide

Specifications

Data transfer rates
Table 3. Data transfer rate specifications
Parameter

Specification

Digital I/O transfer rates (software paced)
Digital input
62 port reads or single bit reads per second typ
Digital output125port writes or single bit writes per second typCounter/timer read/write rates (software paced)Counter read
62 port reads per second typCounter clear
125 port writes per second typ

Power
Table 4 . Power specifications
Parameter
Supply current (Note 2)+5V USB power available (Note3)
Output current (Note 4)

Conditions

Specification

Connected to self-powered hub
Connected to bus-powered hub
Connected to self-powered hub
Connected to bus-powered hub

20 mA typ, 40 mA max
4.5 V min, 5.25 V max
4.1 V min, 5.25 V max
460 mA max
60 mA max

Note 2:This is the total current requirement for the USB-DIO24/37which includes up to 5 mA for the status LED.

Note 3:Self-powered refers to USB hubs and hosts with a power supply. Bus-powered refers to USB hubs and hosts
without their own power supply.

Note 4:This refers to the total amount of current that can be sourced from the USB +5V and digital outputs.

GeneralTable 5. General specifications
Parameter

Conditions

Specification

USB controller clock error

25 °C
0 to 70 °C±30 ppm max±50 ppm max
USB 1.1 low-speed
USB 1.1, USB 2.0

Device type
Device compatibility

Environmental
Table 6. Environmental specifications
Parameter

Specification

Operating temperature range
Storage temperature range
Humidity

0 to 70 °C–40 to 85 °C
0 to 90% non-condensing

12USB-DIO24/37 User's Guide

Specifications

Mechanical
Table 7. Mechanical specifications
Parameter

Specification

Dimensions (L × W × H)
USB cable length
USB cable type

119 mm × 84 mm × 14 mm (4.69 × 3.31 × 0.55 in.)3 m (9.84 ft) max
A-B cable, UL type AWM 2527 or equivalent. (min 24 AWG VBUS/GND, min
28 AWG D+/D-)Main connector and pinout
Table 8. Connector specifications
Parameter

Specification

Connector typeCompatible cables

37-pin D-type
C37FF-x unshielded ribbon cable. x = length in feet.
Table 9. Connector pinout

Pin12345678910111213141516171819Signal Name
CTR
NCPort B Bit 7
Port B Bit 6
Port B Bit 5
Port B Bit 4
Port B Bit 3
Port B Bit 2
Port B Bit 1
Port B Bit 0
GND
NC
GND
NC
GND
NC
GND
+5GNDPin
202122232425262728293031323334353637Signal Name+5GNDPort C Bit 7
Port C Bit 6
Port C Bit 5
Port C Bit 4
Port C Bit 3
Port C Bit 2
Port C Bit 1
Port C Bit 0
Port A Bit 7
Port A Bit 6
Port A Bit 5
Port A Bit 4
Port A Bit 3
Port A Bit 2
Port A Bit 1
Port A Bit 0

13

Declaration of Conformity
Manufacturer:
Address:

Category:

Measurement Computing Corporation
10 Commerce Way
Norton, MA 02766
USAElectrical equipment for measurement, control and laboratory use.

Measurement Computing Corporation declares under sole responsibility that the productUSB-DIO24/37
to which this declaration relates is in conformity with the relevant provisions of the following standards or otherdocuments:
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 61000-4-2 (1995): Electrostatic Discharge immunity, Criteria C.
IEC 61000-4-3 (1995): Radiated Electromagnetic Field immunity Criteria A.
IEC 61000-4-8 (1994): Power Frequency Magnetic Field immunity Criteria A.

Declaration of Conformity based on tests conducted by Chomerics Test Services, Woburn, MA 01801, USA inFebruary, 2006. Test records are outlined in Chomerics Test Report #EMI4445.06.
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
Norton, Massachusetts 02766(508) 946-5100
Fax: (508) 946-9500
E-mail: info@mccdaq.com
www.mccdaq.com

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