Log In

Celebrating 45 Years

Follow us on Facebook for all the latest news, updates and promotions


Credit Cards Accepted


Aurora Probability in Northern Canada

Auroral forecast from AuroraWatch.ca


North America Aurora Map from
NOAA Space Weather Prediction Center

Aurora Map - NOAA





acces i/o logo 
   US Pricelist
CND Pricelist
Privacy and Security Policy

USB Digital Input/Output Module


  • High-Speed USB 2.0 device, USB 1.1 compatible
  • Small (3.5 by 3.7 in.), portable, 32-channel USB digital I/O module
  • Four 8-bit ports independently selectable for inputs or outputs
  • All 32 I/O lines buffered with Sink 64mA / Source 32mA current capabilities
  • Custom high-speed function driver
  • Removable screw terminal adaptor for easy wiring
  • Standard 50-pin IDC connector with key
  • Rugged industrial enclosure
  • Type B USB connector features industrial strength and high-retention design


  • Three 82C54 counter/timers
  • External power for high current capabilities
  • Economy "E" version also available without the screw terminal adaptor
  • OEM (board only) version with pre-drilled mounting holes for added flexibility in embedded applications
  • DIN rail mounting provision
  • RoHS Available. Please contact us for ordering information

The USB-DIO-32 is an ideal solution for adding portable, easy-to-install digital I/O and counter capabilities to any computer with a USB port. The USB-DIO-32 is a USB 2.0 device, offering the highest speed available with the USB bus. It is fully compatible with both USB 1.1 and USB 2.0 ports. The unit is plug-and-play allowing quick connect or disconnect whenever you need additional I/O on your USB port.

The USB-DIO-32 features 32 bits of TTL-compatible digital I/O with high-current capabilities and three optional 82C54 counters. Each digital port can be programmed to accept inputs or to drive outputs on four 8-bit ports, designated as port A, B, C, and D. Power is supplied to the unit via the USB cable or for higher current capabilities, external power may be used. The I/O wiring connections for USB-DIO-32 are via an industry standard 50-pin connector. For external circuits, fused 5VDC power is available at the connector. This resettable fuse is rated at 0.5A.

All I/O lines are buffered by a type 74ABT245 tristate buffer transceiver capable of sinking 64 mA or sourcing 32 mA. The buffers are configured under program control for input or output. Pull-ups (to 5 VDC) or pull-downs (to ground) on the board allow for contact monitoring and assure that there are no erroneous outputs at power-up until the module is initialized by system software.

Unlike most USB digital I/O products which primarily use a human interface device (HID) driver, ACCES offers an easy to use, Windows-based, custom function driver optimized for maximum data throughput. This approach exposes the full functionality of the hardware along with maximizing the advantage of using the high-speed USB 2.0 bus.



The USB-DIO-32 is designed to be used in rugged industrial environments but is small enough to fit nicely onto any desk or testing station. The board is PC/104 sized (3.550 by 3.775 inches) and ships inside a steel powder-coated enclosure with an anti-skid bottom. The OEM (board only) version is perfect for a variety of embedded applications. The board features pre-drilled mounting holes and can be installed using standoffs inside most enclosures or systems. PC/104 systems can easily add this module to an existing stack using the conveniently sized PC/104 mounting holes.

High Retention USB Connector

The ever-growing presence of USB in the industrial/military marketplace has driven the need for USB connections to be reliable, dependable, and unfailing. Gone are the days of lose USB connections. A type B USB connector is used on all ACCES USB/104 products which features a high retention design that complies with the class 1, Div II minimum withdrawal requirement of over 3 pounds of force (15 Newtons). This connector has an orange color-coded insulator to quickly differentiate it from standard USB connectors. Using these USB connectors increases reliability in your system and ensures a tight connection. For embedded OEM type applications, an additional miniature USB input header is provided in parallel with the type B connector.


  • Home
  • Portable
  • Laptop
  • Education
  • Laboratory
  • Industrial Automation
  • Embedded OEM


Three 82C54 chips each include three 16-bit counter/timers factory configured in an optimal module for use as event counters, frequency output, pulse width, and frequency measurement (see the Block Diagram).


The USB-DIO-32 is available with optional cable assemblies, screw termination boards, and an optional external AC/DC power supply. The pin connections are also compatible with industry standard I/O racks such as ACCES A24A, OPTO22, Gordos, Potter & Brumfield, etc. with optional cable.


The USB-DIO-32 includes a free Windows 98se/Me/NT/2000/XP/2003 compatible software package. This contains sample programs and source code in Visual Basic, Delphi, C Builder, and Visual C for Windows. Also incorporated is a graphical setup program in Windows. Third party support includes a Windows standard dll interface usable from the most popular application programs.


Digital Inputs (TTL Compatible)

  • Logic High: 2.0 to 5.0 VDC
  • Logic Low: -0.5 to 0.8 VDC

Digital Outputs

  • Logic High: 2.0 VDC min., source 32 mA
  • Logic Low: 0.55 VDC max., sink 64 mA

Optional Counter/Timers

  • Type: 82C54-10 programmable interval counters
  • Output Drive:
    • 2.0 VDC min., source 32 mA
    • 0.55 VDC max,. sink 64 mA
  • Input Gate: TTL/CMOS compatible
  • Clock: On-board, 3 MHz crystal-controlled clock
  • Active Count Edge: Negative Edge
  • Minimum Clock Pulse Width: 30 nS high, 40 nS low
  • Timer Range: 16 bits
  • Maximum Input Frequency: 10MHz


  • Operating Temperature Range: 0° to 70°C
  • Storage Temperature Range: -40° to 85°C
  • Humidity: Maximum 90% RH, without condensation
  • Board Dimension: 3.550 x 3.775 inches
  • Box Dimension: 4.00 x 4.00 x 1.25 inches


  • 5VDC provided via USB cable up to 500mA**
  • Basic Unit with Three Counters: 80mA typical (no load)

**optional external power supply can be ordered if the SOURCE current from the USB-DIO-32 is expected to be greater than 420mA (80mA 420mA = ~500mA)

Connector Pin Assignments

USB-DIO-32 has a 50-pin connector provided for I/O connections. Connector pin assignments are listed below.

Assignment Pin Assignment Pin
Port C PC7 1 Counter A0 Freq In 2
Port C PC6 3 Ctr A1 P.W.I. (Gate) 4
Port C PC5 5 Counter A2 Freq Out 6
Port C PC4 7 Counter B0 Freq In 8
Port C PC3 9 Ctr B1 P.W.I. (Gate) 10
Port C PC2 11 Counter B2 Freq Out 12
Port C PC1 13 Counter C0 Freq In 14
Port C PC0 15 Ctr C1 P.W.I. (Gate) 16
Port B PB7 17 Ctr C2 Freq Out 18
Port B PB6 19 Port D PD7 20
Port B PB5 21 Port D PD6 22
Port B PB4 23 Ground 24
Port B PB3 25 Port D PD5 26
Port B PB2 27 Ground 28
Port B PB1 29 Port D PD4 30
Port B PB0 31 Ground 32
Port A PA7 33 Port D PD3 34
Port A PA6 35 Ground 36
Port A PA5 37 Port D PD2 38
Port A PA4 39 Ground 40
Port A PA3 41 Port D PD1 42
Port A PA2 43 Ground 44
Port A PA1 45 Port D PD0 46
Port A PA0 47 Ground 48
Fused 5 VDC . 49 Ground 50

Regulatory Compliance

  • This product is designed to be in full compliance with CE requirements.


When ordering RoHS products, please identify this need by using a unique model number suffix, "-RoHS" on all orders. For pricing and lead times, please contact your sales representative.
Part NumberPrice(USD)
USB-DIO-32 169.00
USB-DIO-32E 139.00
USB-DIO-32-OEM 119.00
USB-DIO-32 - Standard module with screw terminal board
UTBK-50 50 pin screw terminal board $49
MP104-DIN DIN rail mounting provision $19
Options (call for pricing)
-OEM Board only model, no enclosure or screw terminal board
-E Economy module, no screw terminal board
-P External power components and AC/DC adapter
-Cx (where x = 1, 2, or 3) Optional counters on board

View / Download Data Sheet (in .pdf format)

View / Download Manual (in .pdf format)

Acquisition Control Communications Engineering / Systems

USA Office

Address: 1480 Gulf Road, Suite 837,
PO Box 1364
Point Roberts, WA 98281

Western Canada - Vancouver BC

Tel:1.800.663.6001 or 1.604.925.6150
Address: 2454 Haywood Ave
West Vancouver, BC V7V 1Y1

Eastern Canada - Markham, Ontario

Tel:1.800.465.0164 or 1.905.513.7027