High-Speed Multifunction Analog I/O Board


  • 16-bit, high-speed (up to 500KHz) multifunction analog I/O
  • 16 single-ended or 8 differential inputs
  • 11 software/hardware selectable ranges of:
    • 0-1V, 0-2V, 0-4V, 0-5V, 0-10V, ±0.5V, ±1V, ±2V, ±2.5V, ±5V, ±10V
  • 1024 sample data FIFO for A/D
  • Auto calibration
  • Two 12-bit D/A outputs and 16 digital I/O

Factory Options: (call for pricing and availability)

  • FIFO up to 64K sample
  • Factory input range/gain of 1-100
  • Medium performance version available (Model 104-AIO16-16)
  • +5VDC only operation
  • 0 to 70°C and -40 to +85°C versions available
  • RoHS Available. Please contact us for ordering information
The 104-AIO16-16W is a multifunction high-speed analog-to-digital and digital-to-analog converter board for use in PC/104-bus computers. With these boards installed the computer can be used as a precision data acquisition and control system or as a signal analysis intrument. Two versions of the board are available and the main differences are classified as follows:
Function 104-AIO16-16W 104-AIO16-16
Analog Input Burst Mode (single channel) 500K samples per second 300K samples per second
Analog Input Multi-Channel Mode (2 or more channels) 450K samples per second total 250K samples per second total
Analog Output (DAC) update rate 100K conversions per second 10K conversions per second


The board accepts up to eight differential or 16 single-ended analog input channels. Inputs are protected against over-voltage conditions. The channel input configuration is selectable through the use of jumpers on the board. In the differential mode the common mode rejection ratio is a typical 90 dB and the common mode voltage rejection capability is ±11V.

Input voltage ranges of 0-1, 0-2, 0-4, 0-5 and 0-10 volts unipolar and ±0.5, ±1, ±2.0, ±2.5, ±5, ±10 volts bipolar are available.

The board contains an industry standard ADS 8322 16-bit successive-approximation analog-to-digital converter (A/D) with a sample and hold amplifier input. It also includes a 1024 sample FIFO data buffer. This allows data to be taken with little processor overhead. Depending on the application and operating system, you may want to select a larger FIFO for smoother performance.


An AD8522 two channel D/A converter is provided. Output voltage ranges of 0-5 and 0-10 volts are available from each channel.


Sixteen bits of TTL/CMOS compatible digital I/O lines are provided. Bits are selectable as inputs or outputs in groups of eight. Digital outputs are available with LSTTL logic levels and have current drive capability of sourcing 32mA or sinking 64mA per line.


The board contains 3 counter/timers in one type 8254 chip.

Counter/Timer 0 is enabled by a pin on the connector (CTR0). It uses an external clock which may have a frequency of up to 10 MHz.

Counter/Timers 1 and 2 are concatenated to form a 32-bit counter and receive 10 MHz clock inputs (divided down to 5, 2.5, or 1.25 MHz) from an on-board crystal-controlled oscillator.

These counter/timers can be set up for event counting, frequency or period measurements, and pulse or wave form generation. Also, Counter/Timers 1 and 2 can be programmed to initiate A/D conversions. A driver with source code is provided to facilitate use of the counter/timer chip in data acquisition applications.


The interrupt for the board can be software enabled and can be initiated by the completion of an A/D conversion, or by various FIFO status conditions.


These boards have been designed to provide high data throughput. Direct I/O transfers may provide the easiest means of transferring the data to memory.

Also, since program transfers are subject to disruption by other interrupt processes in the computer, use of real time triggering of the A/D assures synchronized sampling that is unaffected by other computer operations. This capability is essential in applications such as signal analysis, vibration and transient analysis where high data rates must be sustained for short intervals of time. The FIFO on the board allows it to acquire data from the signal source and to store the data in the onboard FIFO, eliminating most timing concerns.


The board’s logic circuitry is powered from the +5V computer supply. The signal conditioning normally operates on the ±12VDC from the PC/104 bus. If these voltages are unavailable, an optional board mounted DC/DC converter is available, which will provide all of the required power from the +5V computer supply.


Header type connectors are available on each side of the board. P1 has 26 pins, including the A/D inputs and D/A outputs. P2 has 40 pins, including the Digital I/O and Counter/Timer connections.


Drivers provided for use in Windows operating systems (XP -> 10, both 32 & 64 bit), samples provided for DOS, Linux, and Windows in a variety of languages. A graphical user setup program makes configuring the board easy.

Drivers and Downloads

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

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.

Available Reference Manuals

Available Datasheets

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.


Analog Inputs

  • Inputs: 16 single ended or 8 differential
  • Ranges: 0-1, 0-2, 0-4, 0-5, 0-10, ±0.5, ±1, ±2.0, ±2.5, ±5, ±10 Volts
  • Over Voltage Protection: ±33V
  • Type: Successive approximation
  • Resolution: 16 Bit
  • Sampling Speed: Up to 500KHz
  • Conversion Time: 1.75 µsec typical (when used with the standard 10 MHz clock)
  • Int. Linearity Error: ±1 LSB Max, Monotonic
  • Diff. Non-Linearity: No missing codes to 14 bits
  • Monotonicity: Guaranteed over operating temperature range
  • Linearity: ±4 bits typical, ±8 bits max
  • Zero Drift: ±10 PPM/°C maximum
  • Gain Drift: ±45 PPM/°C maximum
  • Trigger Source: Software selectable, external trigger, programmable timer, A/D start, Single Scan Start, or program command

Automatic Calibration

    The board loads appropriate gain and offset constants, from an onboard non-volatile memory to adjust the A/D inputs and D/A outputs to be within specification. Software is provided for periodic calibration of the board.

Analog Outputs

  • Channels: 2
  • Resolution: 12 bit
  • Ranges: 0-5V, 0-10V
  • Output current: 5mA
  • Calibration: Automatic with values stored in EEPROM
  • Settling Time: 8µs

Digital I/O

  • Channels: 16
  • Input Voltage:
    • Logic low: 0.03V min, 0.8V max
    • Logic High: 2.0V min, 5.0V max
  • Input Current: ±1uA Max
  • Output Voltage:
    • Logic low: 0.0V min, 0.55V max
    • Logic High: 2.4V min, 5.0V max
  • Output Current:
    • Logic low: 64mA Sink
    • Logic High: 32mA Source


    Appropriate gain and offset constants to adjust the output to be within specification are loaded into the board, after retrieval from the onboard memory.

Programmable Timer

  • Type: 82C54-2 programmable interval timer, with 3 counter stages.
  • Counters: One is internally connected to provide timing for the A/D circuitry.
  • Output Drive: 2.5mA (5 LSTTL loads).
  • Input Gate: TTL/DTL/CMOS compatible.
  • Clock Frequency: 10MHz.
  • Active Count Edge: Negative edge.
  • Min Clock Pulse Width: 30nS high/50nS low.
  • Timer Range: 5 MHz to <1 pulse/hr.


  • Operating Temp: 0 to 70°C (-40 to 85°C Optional)
  • Storage Temp: -50 to +120°C.
  • Humidity: 5 to 90% RH, non-condensing.
  • Power Required:
    • +12VDC: 25 mA typical.
    • -12VDC: 20 mA typical.
    • +5VDC: 50 mA typical.
  • Power Required (using only +5V, with the optional DC/DC Converter):
    • +5VDC:180 mA.

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

ModelPrice (USD)

Acquisition, Control, Communication: Engineering and Systems

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