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Isolated Digital Output Card


  • Individually-isolated digital outputs for up to three 16-bit groups
  • All solid-state design permits higher throughput than possible with electromechanical relays
  • Load voltages up to 60 Volts
  • On-Card shields prevent accidental contact with user voltages
  • Outputs at zero volts at power turn-on and computer reset
  • Output connectors via on-card ribbon-cable headers
  • Lower cost per point than externally-racked solid-state relay modules

IDO-xx Series cards provide 16, 32, or 48 opto-isolated differential outputs and plug into expansion slots of IBM PC/XT/AT or compatible computers. Solid-state, P-Channel FET switches are used as the output elements and provide both greater reliability and much faster turn-on and turn-off time than is possible with electromechanical relays. User-supplied load voltages can be from 5V to 60V. Output connections are via 50-wire ribbon cables that mate with headers on the card. A strain relief bar where the cables exit the card assures that the cables will not interfere with adjacent cards. Standard cables are six feet long but alternate lengths are available. Model STA-50 Screw Terminal Accessory cards, one per each 16 bits, can be used to provide easy connection to your system.

The card uses six bytes of I/O Bus address; one byte for each eight bits of output. Outputs of a programmable array logic chip enable data bytes to be clocked into latches. Outputs of the latches, in turn, are connected via opto-couplers to the output P-channel FET drivers. The opto-couplers used are rated to 5 KV and on-card isolation channel-to-channel and channel-to-computer exceeds 60 Vrms. The P-Channel FET drivers are capable of 1 Ampere steady-state current (Note: Current output may be limited by the cable to as little as 0.5A). Diodes are included across the load for inductive-spike protection.

There are 48-bit, 32-bit, and 16-bit versions. The latter two models are de-populated versions of the 48-bit card.

Each bit of the IDO card is optically-isolated from the output driver which switches the supply voltage to the output pin. The negative connection is made on the return pin and each output is isolated from every other output.

When the opto-isolator is ON, the FET is activated by the Zener-diode-limited supply voltage. When the FET is ON, the full Supply voltage is available at the output pin. When the opto-isolator is deactivated, the FET opens and the output drops to the return line voltage level.

Note, because high voltages can be present, a protective cover is included and cables plugged into the headers on the card extend through this cover and exit the card through a cutout in the mounting bracket. (A strain-relief bar is also provided at that exit point.) If there is the possibility that some other card in your system will have sharp trimmed component leads that could pierce the cable(s), then you can use shielded "Zippertubing" (our part number ZTR-xx) to protect the cable and prevent possible short circuits.


Digital Outputs

  • Number of Channels: 16, 32, or 48
  • Load Voltage Range: 5V to 60V (Voltage supplied by User)
  • Load Current per Channel: 1 Ampere max. steady state, 2A pulse.
    (Note: Current may be limited by the cable. Certain ribbon cables limit current to 0.5 A.)
  • Isolation:
    On-Card: 60V rms, channel-to-channel and channel-to-computer
    Cable: 300 Vrms is typical ribbon-cable dielectric strength
  • Switching Time:
    Turn-On: 50 µsec
    Turn-Off: 2 µsec, inductive-spike protection via a diode
  • Switch Resistance: 0.4 ohms when saturated
  • Switch Leakage Current: 1 uA


  • Operating Temperature: 0 to 60 degree C.
  • Storage Temperature: -20 to 100 degree C.
  • Humidity: 5% to 95% non condensing.
  • Size: 13.310 inches. Install in a full-size slot.

Power Requirements

  • 5 VDC at 540 mA typical for fully populated 48 bit card

Regulatory Compliance

  • This product is in full compliance with CE requirements.

Part NumberPrice(USD)
View / Download Manual (in .pdf format)
Acquisition Control Communications Engineering / Systems
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