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104-IDI-48 Family

48-Channel Optically Isolated Digital Input Boards


  • 48 individually optically isolated AC/DC inputs
  • Polarity-insensitive AC/DC inputs accept up to 60 VDC or AC rms
  • AC or voltage transient filtering
  • Optically isolated channel-to-channel and channel-to-ground
  • Designed, made, supported, and manufactured in the USA

Factory Options: (call for pricing and availability)

  • 0 to 70°C and -40 to +85°C versions available
  • Change-of-state detection (COS IRQ) on selected inputs
  • Higher input ranges
  • Right-angle or vertical I/O connectors
  • RoHS Available. Please contact us for ordering information

The 104-IDI-48 family boards are 48-channel PC/104 utility boards which feature 48 individually optically isolated digital inputs. They are ideal for use in control and instrumentation applications where high voltage protection is required. Individual channel-to-channel isolation allows every channel to be physically and electrically separated from the others.

Enabled inputs feature a change-of-state detection capability (denoted by a "C" at the end of the model number) which provides a means to automatically interrupt the host computer in real time. When one or more input bits change state, an interrupt is generated to automatically wake up your application. This can greatly simplify your application program and eliminate the need to continuously poll inputs. Each input is rectified by photo-coupler diodes, and is therefore polarity-insensitive - positive, negative, and AC voltage inputs are all acceptable. Zero crossings and glitches are eliminated by input filters. The input range is up to 60 VDC or AC rms at frequencies of 40 Hz to 10 kHz.

ModelNo. of BitsMax Input VoltageChange-of-State
Interrupt Capability
AC Filter

These boards are especially useful in applications where high common-mode external voltages are present. Isolation is required to guard electronics from transient voltage spikes and offers greater common-mode noise rejection in electronically noisy surroundings containing industrial machinery and inductive loads. These applications include factory automation, energy management, industrial ON/OFF control, security systems, manufacturing test, and process monitoring. In addition to protecting industrial applications from accidental contact with high external voltages, the isolation provided eliminates troublesome ground loops. The optically-isolated digital inputs are split into two 50-pin IDC-type headers, each containing 24 channels. Accessories available include a wide variety of ribbon cables and screw terminal boards for quick and easy connectivity.

These PC/104 boards can be installed in any embedded system that supports PC/104 or PC/104+ modules. I/O connectors ship standard as right-angle pin type but can also be ordered as vertical to avoid obstructions by other system components or enclosure constraints. This high-density I/O board is available with a variety of options such as an economy version (no change-of-state), extended temperature (-40C to +85C), higher input ranges, etc. Let us know what you need for your OEM application and we'll supply it, saving you time and money by buying only what you need.

If you'd like this board delivered in an embedded system, we'd be glad to provide integration at a competitive rate. Consider using it as part of our ETX-NANO-104 motherboard, our rugged E4-DAS Fanless Embedded Computer, or our IE-DAS Embedded System. For complete details on that and our other fine products give us a call at 800-326-1649 and speak with an application specialist that can help find a solution that is right for you and your project.

  • Factory automation
  • Energy management
  • Industrial ON/OFF control
  • Security systems
  • Manufacturing test
  • Process monitoring

These boards are supported for use in most operating systems and include a free software package compatible with DOS, Linux, and Windows XP -> 10, both 32 & 64 bit. This package contains sample programs and source code in "C" for DOS, and Visual Basic, Delphi, and Visual C++ for Windows. Also incorporated is a graphical setup program in Windows. Linux support includes installation files and basic samples for programming from user level via an open source kernel driver.

Available Reference Manuals

Available Software Downloads

Available Datasheets

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 Windows XP through Windows 10, including "Server 2008," "Embedded," and "Compact" flavors in both 32-bit and 64-bit 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 Visual C# and Delphi with many devices including samples in Visual Basic and Visual C/C++, as well as Borland C/C++ 3.1 for DOS. Additionally we provide National Instruments LabVIEW compatible DLLs and demonstration VIs for many of 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 Linux kernels 2.6 and newer and recent 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 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.

non-plug-and-play driver install guide for Windows

Please refer to the Non-PnP Install Guide for instructions to get your PC/104 and ISA bus devices installed in modern Windows.

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.


Isolated Digital Inputs

  • Number of inputs: 48
  • Type: Non-polarized, optically isolated from each other and from the computer. (CMOS compatible)
  • Voltage Range:
    • 48A:
      • Logic Low: 0 to 1.5 VDC or AC rms (40 to 10,000 Hz)
      • Logic High: 3 to 31 VDC or AC rms (40 to 10,000 Hz)
    • 48B:
      • Logic Low: 0 to 5 VDC or AC rms (40 to 10,000 Hz)
      • Logic High: 11 to 60 VDC or AC rms (40 to 10,000 Hz)
  • Isolation: Opto-isolators and connectors are rated for at least 500V channel-to-ground or channel-to-channel, but isolation voltage breakdowns will vary and is affected by factors like cabling, spacing of pins, spacing between traces on the PCB, humidity, dust and other environmental factors. This is a safety issue so a careful approach is required. For CE certification, isolation was specified at 60 VDC or AC rms. The design intention was to eliminate the influence of common mode. Use proper wiring techniques to minimize voltage between channels and to ground. Tolerance of higher isolation voltage can be obtained on request by applying a conformal coating to the board.
  • Input Resistance:
    • 48A: 1.8K Ohms in series with opto coupler
    • 48B: 15K Ohms in series with opto coupler
  • Non-Filter Response Times:
    • Rise Time: 10 uS
    • Fall Time: 30 uS
  • Filter Time Constant: 4.7ms


  • Interrupts: Software controlled with jumper IRQ selection (models 104-IDI-48AC and 104-IDI-48BC)

Power Required

  • +5VDC @ 300mA typical


  • Operating Temp: 0° to +70°C, (-40 to +85°C Optional)
  • Storage Temp: -55 to +150°C
  • Humidity: 5% to 95% RH, without condensation
  • Board Dimension: PC/104 format, 3.550" by 3.775"

CE testing & approval must be done at the system level, in the designed enclosure, and is not done on individual boards.

ModelNo. of BitsMax Input VoltageChange-of-State
Interrupt Capability
AC Filter
ModelPrice (USD)

Acquisition, Control, Communication: Engineering and Systems