USBP-DIO16RO8 USB, Pico-I/O™ Sized Digital I/O and Relay Board Family

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  • High-speed USB 2.0 device, USB 3.0 and 1.1 compatible
  • 16-channel TTL/LVTTL digital I/O
  • All 16 I/O lines buffered with 32mA sink/source current capabilities
  • 8 Form C electromechanical relays switch 1A
  • Custom high-speed function driver
  • Alternate embedded USB connector
  • All required power drawn from USB port, no external power adapter required
  • Pico-I/O™ module size (60mm x 72mm) & mounting capability
  • Designed, made, supported, and manufactured in the USA


  • Extended temperature (-40°C to +85°C) operation
Last updated on October 5, 2023, 10:31 am


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Tiny USB OEM Module Provides 16 TTL/LVTTL Digital I/O and 8 Relay Outputs

The USBP-DIO16RO8 is an ideal OEM USB solution for adding embedded, easy-to-install buffered TTL/LVTTL digital I/O and relay output capabilities to any computer with a USB port. The USBP-DIO16RO8 is a USB 2.0 (1.1 compatible) high-speed device, offering the highest speed available with the USB Bus. The unit is hot pluggable allowing quick connect or disconnect whenever you need additional I/O in your system.

The unit can be installed in single or multiple stack configurations. It can also be mounted alone near I/O sensors or devices to be controlled in a star configuration away from the USB ports of its host embedded computer. The module is always connected by USB cable to any computer USB port via its external micro B connector or on-board friction-lock micro-fit connector.

Featuring 8 Form C (SPDT) electro-mechanical relays and 16 TTL/LVTTL buffered digital I/O lines, the unit is the smallest of its kind for digital monitoring and control using USB. This mix of programmable inputs and outputs together with the dedicated relays allows system designers greater flexibility while containing overall costs. The digital I/O lines have 32mA of both sink and source to drive external components and are available via a 34-pin IDC type vertical header. The pinout allows a simple accessory cable to interface to our 50-pin external signal conditioning products. The board can be switched from 5V to 3.3V signaling to match a particular device connected. The 8 relay outputs are de-energized at power-up to prevent an unintended control output signal. Data to the relays is latched. The relay contacts are available via a 26-pin IDC vertical header-keyed box type connector.

The USBP-DIO16RO8 draws all required power from the USB port, no external power adapter is required. The small size and easy connection makes the unit an excellent choice for a variety of embedded applications such as mobile, robotics, kiosks, and embedded medical and machine equipment.

The USBP-DIO16RO8 is designed to be used in rugged, industrial, and mobile environments and has the option to be upgraded to extended temperature specifications. The board is tiny Pico-I/O™ sized (60mm by 72mm) making it ideal for the smallest of embedded applications.


The tiny module occupies just half the area of a PC/104 board yet approaches the capability commonly found on the larger board standard. This board is perfect for deployment into space-limited applications and follows the ever-shrinking platform of the single board computer into the Pico-ITXe standard by VIA and other manufacturers.

The board is ideal for a variety of embedded applications. The USBP-DIO16RO8 can also be installed using standoffs inside a assortment of enclosures or systems. For embedded OEM type applications, an additional miniature USB input header is provided in parallel with the type B micro connector. What makes the USB/PICO form factor unique is that its PCB size and pre-drilled mounting holes match the Pico-I/O form factor (without the bus connections). This ensures easy installation using standard standoffs with any Pico-ITXe single board computer. The board can be added to any Pico-I/O stack by connecting it to a USB 2.0 port included on-board with the embedded CPU.


  • Mobile
  • Robotics
  • UAVs
  • Kiosks
  • Medical
  • Portable
  • Automation
  • Energy Management and Conservation


The USBP-DIO16RO8 is available with optional cable assemblies, screw terminal boards and external signal conditioning boards supporting high current relays, 120/240AC modules and optical isolated inputs.


The USBP-DIO16RO8 utilizes a high-speed custom function driver optimized for a maximum data throughput that is 50-100 times faster than the USB human interface device (HID) driver used by many competing products. This approach maximizes the full functionality of the hardware along with capitalizing the advantage of high-speed USB 2.0. The USBP-DIO16RO8 is supported for use in most operating systems and includes a free Linux (including Mac OS X) and Windows XP -> 10, both 32 & 64 bit compatible software package. This package contains sample programs and source code in Visual Basic, Delphi, 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 and includes example LabVIEW VIs. Embedded OS support includes Windows Xpe, WES7, etc.






Data Sheets



Drivers and Downloads

Full list of available Downloads: Software Packages, Drivers, Manuals, and other documents

Information about our Free Software packages:

ACCES is proud to provide a full suite of software support with every Data Acquisition product. We are committed to supporting the most popular operating systems and platforms for our customers. Currently we are actively supporting XP -> 10, both 32 & 64 bit, including “Server 2008,” “Embedded,” and “Compact” flavors for all plug-and-play products including PCI, PCI Express, USB, and more. Many products continue to ship with support for additional operating systems such as DOS, Windows 95, 98, Me, NT4, and 2000.


Among the software we deliver with our products are sample programs in a wide variety of programming languages. These samples are used to demonstrate the software interfaces to our products — and many can be used as-is in your production environments, or to test functionality of the devices out-of-the-box. We’re currently actively supporting sample programs in Microsoft Visual C#, Visual Basic, Delphi, and Visual C/C++, with many devices including samples in Borland C/C++ 3.1 for DOS. Additionally we provide National Instruments LabVIEW compatible DLLs and many demonstration VIs for our devices.


Drivers for various operating systems are also provided, including active support for Windows XP -> 10 — all in both 32-bit and 64-bit flavors, and including consumer, server, and embedded varieties — as well as the 2.6 and newer Linux kernels and recent OSX / macOS versions. Many products continue to ship with driver support for Windows 95, 98, Me, NT4, and Windows 2000, but support for these operating systems is considered deprecated.

Setup Programs and Utilites

Our Data Acquisition devices also include a graphical setup utility that walks you through the process of configuring any option jumpers or switches on the device, as well as explaining a little about the various connectors present.

Many devices also include utility programs – little tools to make your use of the device easier, such as EWriter, a program that allows you to read and write data in the user-accessible EEPROM locations on all our USB data acquisitition products; or WinRISC, a “Really Incredibly Simple Communications” terminal program that lets you get started instantly with serial devices.

“Register Level” Documentation

Besides all this software in all these languages and operating systems ACCES has a policy of open and transparent development: none of our lowest-level “register” interfaces are hidden from you — we document every register in every bus card, every command in every serial board, and every usb control transfer in every USB Data Acquisition board. These lowest-level interfaces allow you to develop for our products in ANY operating system or language, regardless of our actively supporting it or having a driver for it. We have customers actively developing in ADA, Android, Python, Java, MATLAB, Solaris, and more, just by referring to our complete low-level interface documentation! And we provide the full source code to all of our drivers, regardless of operating system, to give you an even bigger head start in your own development tasks.

No Fees or Royalties

All of this software is provided at no additional charge, and is licensed under any of a variety of flexible — and royalty free — options. Check out our software license explanation if you’d like more information.

Custom Software

ACCES also offers Custom Software Services for our products. Our prices are unbelievably low, often as inexpensive as free! If you need something tweaked to support your needs, or an entire enterprise application developed from scratch, it is definitely worth your time to inquire with us, first.

Further information about available ACCES Software:

Redistributing Windows Drivers
A list of ACCES drivers and the files that compose them under different versions of Windows, so you can easily redistribute ACCES cards and drivers.

Digital I/O

  • Number: 16
  • Connector: 34-pin vertical IDC header
  • Signaling: 5V / 3.3V signaling selectable

Digital Inputs (TTL Compatible) 5V signaling

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

Digital Outputs 5V signaling

  • Logic High: 2.0 VDC minimum, source 32 mA
  • Logic Low: 0.55 VDC maximum, sink 32 mA

Relay Outputs

  • Number: Eight(8) SPDT form C
  • Connector: 26-pin vertical ID keyed box header
  • Contact Type: Single crossbar; Ag with Au clad
  • AC Load: 0.5 A @ 125 VAC (62.5 VA max.)
  • DC Load: 1A @ 24 VDC (30 W max.)
  • Switching Voltage: 125 VAC, 60 VDC max.
  • Switching Current: 1A max.
  • Contact Resistance: 100 mω max
  • Contact Life: mechanical: 5 million operations min.
  • Operating Time: 5 msec max.
  • Release Time: 5 msec max.

Bus Type

  • High-speed USB 2.0 device, USB 3.1 and 1.1 compatible

Bus Connectors

  • USBP-DIO16RO8 Micro B external connector, 5-pin micro-fit connector on-board


  • Operating Temperature Range: 0° to 70°C (-40° to +85°C extended temperature option)
  • Storage Temperature Range: -40° to +85° C
  • Humidity: Maximum 90% RH, without condensation.
  • Board Dimension: 60mm x 72mm.


  • +5VDC provided via USB bus up to 500mA**
  • 5V @ 30mA, typical (all relays off, add 30mA per relay)
  • 5V @ 270mA, typical (all relays ON) **If the application expects to have all relays On, the amount of power to source any of the 16 digital I/O must be limited to less than 230mA or an average of 14mA per channel. Example: If eight of the channels are being used as inputs, then eight other digital lines could source 28mA average on their outputs.
ModelDescriptionPrice (USD)

Pico-I/O™ module size 16 TTL/LVTTL Digital I/O and 8 Relay Output USB Board, micro-B


Pico-I/O™ module size 16 TTL/LVTTL Digital I/O Board, micro-B

STBP-DIO16RO8 Direct connect 60-pin spring-cage terminal board for use with USBP-DIO16RO8 $79
STBP-DIO16 Direct connect 32-pin spring-cage terminal board for use with USBP-DIO16 $59
UTBK-26 26 pin screw terminal board $39
Model Options (call for pricing)
-T Extended temperature (-40°C to +85°C) operation