AIO8   8 Channel Analog Input ISA Card

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  • Eight A/D channels, 12-bit resolution
  • Programmable scan rate
  • Foreground/background operation
  • Seven bits digital I/O
  • Three 16-bit programmable counter/timers
  • Can assert interrupts
  • Event, period, pulse, and pulse-width counting
  • Designed, made, supported, and manufactured in the USA
  • Resettable fused +5 VDC output available
  • ‘H’version compatible with industry standard I/O racks like Grayhill, Opto 22, Western Reserve Controls, Potter and Brumfield, etc.
  • Optional 10 MHz counters
  • Automatically detected under Windows
  • No base address or IRQ switches to set
  • RoHS Available. Please contact us for ordering information
  • Support for Wind River VxWorks (call for ordering information)
Last updated on November 2, 2023, 6:30 pm


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AIO8 is an economical multifunction, moderate-speed, multiplexed analog-to-digital converter card with digital I/O and with counter/timers. It can be used with ISA-bus computers. The card is 7″ long and requires one slot in the computer. All external connections are made through a standard 37-pin D-type connector at the rear of the computer. PC bus power (+5V, +12V, and -12V) is provided at the rear connector. This allows additional user-designed interfaces for input signal conditioning, expansion multiplexers, etc.


AIO8 accepts eight analog inputs. The full-scale input for all analog channels is ±5V (0.00244V resolution). Inputs are single-ended with a common ground and can withstand a continuous overload of ±30V and brief transients of several hundred volts. The A/D converter is a 12-bit successive-approximation type with sample and hold input. Conversion time is typically 25 microseconds (35 microseconds max.) and, depending on the software and the computer used, throughput rates up to 4,000 samples/second are attainable.


Seven bits of discrete digital I/O are provided; one 4-bit output port and one 3-bit input port. Each output can drive five standard TTL loads. The output port, if not used to select analog input expansion channels, may be used for general purpose applications.


The card supports up to eight AIM-16 or LVDT-8 analog input expansion cards (or mixtures). A 3-bit standard LSTTL logic output from AIO8 is used to select any one of the LVDT inputs at an LVDT-8 and a 4-bit LSTTL logic output from AIO8 is used to select one of 16 analog input channels at the AIM-16. The eight-input analog multiplexer on the AIO8 card is software addressable and an input expansion card can be connected to each input for a maximum of 128 analog data channels in the system. To accommodate more than 128 inputs, either a second AIO8 (and companion input expansion cards) can be used or you may wish to consider using the AD12-16.


A type 8254 counter/timer chip is included on the card. This chip contains three separate 16-bit down counters. One of the counters is connected to a submultiple of the system bus clock and all I/O functions of the other two counters are available to you at the I/O connector. The counters can be used to generate periodic interrupt requests, for event counting, pulse and waveform generation, frequency and period measurements, etc. Timed A/D conversions may be initiated by the counter/timer if a jumper is installed on the I/O connector. Also, software provided by ACCES includes means to use these counters to provide programmable gain commands to the instrumentation amplifier on board the AIM-16 expansion multiplexers.


Interrupts are supported from external inputs. Selection of input levels IRQ2 through IRQ7 is made by jumper on the card. Interrupts are software enabled and disabled. An interrupt request may be canceled by either:

  • a) Computer reset signal, or
  • b) Writing a command word to the card; i.e., by either updating the channel selection on the associated AIM-16 expansion card or on the AIO8 multiplexer.



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.


Analog Inputs

  • A/D Type: Successive approximation.
  • Resolution: 12-bit binary. Coding is offset binary.
  • Number of Channels: 8 single-ended inputs w/common ground.
  • Voltage Range: ±5 VDC.
  • Overvoltage Protection: ±30 VDC.
  • Input Impedance: 10 Megohm or 100 nA at 25°C.
  • Accuracy: 0.02% of reading ±1 LSB.
  • Linearity: ±1 LSB.
  • Temp. Coefficients: ±10 µV/°C zero stability. ±25 µV/°C gain stability.

Digital Inputs / Outputs


  • Logic Low: 0 to 0.4V at 8 mA sink.
  • Logic High: 2.4 to 5.0V at 0.4 mA source.


  • Logic Low: 0 to 0.4V at 8 mA sink.
  • Logic High: 2.4 to 5.0V at 0.4 mA source.


  • No. of Counters: Three 16-bit down counters. Clock input to one is ½ the PC system clock frequency; clock inputs to the others can come from external sources.
  • Input Voltage Levels:
    Low: 0 to 0.8V.
    High: 2.4 to 5.0V.
  • Output Voltage Levels:
    Low: 0 to 0.45V at up to 2.0 mA sink.
  • Clock Period: 125 nSec min.
  • Clock Rise and Fall Time: 25 nSec max.


  • Operating Temperature Range: 0° to 60°C.
  • Storage Temperature Range: -20° to +70°C.
  • Humidity: 0 to 90% RH, non-condensing.

Regulatory Compliance

  • This product is in full compliance with CE requirements.
  • MOQ’s may be required.
ModelDescriptionPrice (USD)

8 A/D input ISA card