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Low Profile Isolated Digital Input/Output Card 



  • 8 optically-isolated, non-polarized CMOS compatible digital inputs accept ±31volts DC or AC rms
  • 8 form C electro-mechanical relays switch up to 1 A each
  • Universal PCI, PCI-X, 3.3V and 5V compatible (Call for PCI-Express availability)

The LPCI-IIRO-8 is a half-size Low-Profile PCI bus compatible card that provides isolated digital input and output interface for PCI-Bus computers. The card has eight optically-isolated digital inputs for AC or DC control signals and eight electromechanical relay outputs. LPCI-IIRO-8 occupies four consecutive 8-bit registers in I/O space.


The LPCI-IIRO-8 provides eight optically-isolated inputs. These inputs can accept either AC or DC signals and are not polarity sensitive. Input signals are rectified by photocoupler diodes while unused power gets dissipated thru a 1.8k-ohm resistor in series. The inputs may be driven by either DC sources of 3 to 31 volts (rms) or AC sources at frequencies of 40 Hz to 10 KHz. Standard 12/24 AC control transformer outputs can be accepted as well. External resistors connected in series may be used to extend the input voltage range, however this will raise the input threshold range. Consult with factory for available modified input ranges.

Each input circuit contains a switchable filter that has a 4.7 millisecond time constant. (Without filtering, the response is less then 40 microseconds) The filter must be selected for AC inputs in order to eliminate the on/off response to AC. The filter is also valuable for use with slow DC input signals in a noisy environment. The filter may be switched out for DC inputs in order to obtain faster response. Filters are individually selected by jumpers. The filters are switched into the circuit when the jumpers are installed in position FLT0 to FLT15.


The board's outputs are comprised of eight FORM C SPDT electro mechanical relays. These relays are all de-energized at power-on.

Isolated Inputs

  • Number of inputs: Eight
  • Type: Non-polarized, optically isolated from each other and from the computer (CMOS compatible)
  • Voltage Range: 3 to 31 DC or AC Rms (40 to 10000 Hz)
  • Isolation: 500V*(see note) channel-to-ground or channel-to channel
  • Input Resistance: 1.8K ohms in series with opto coupler
  • Filter Response Times: Rise Time = 4.7 mS / Fall Time = 4.7 mS
  • Non-Filter Response Times: Rise Time = 10 uS / Fall Time = 30 uS
*Notes on Isolation: Opto-Isolators and connectors are rated for at least 500V, 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 40V AC and 60V DC. The design intention was to eliminate the influence of common mode. Use proper wiring techniques to minimize voltage between channels and to ground. For example, when working with AC voltages do not connect the hot side of the line to an input. Tolerance of higher isolation voltage can be obtained on request by applying a conformal coating to the board.

Relay Outputs

  • Number of outputs: Eight SPDT form C
  • Contact Type: Single crossbar; Ag with Au clad
  • Rated Load AC: 0.5 A at 125 VAC (62.5 VA max.)
  • Rated Load DC: 1A at 24 VDC (30 W max.)
  • Max. Switching Voltage: 125 VAC, 60 VDC
  • Max. Switching Current: 1 A
  • Contact Resistance: 100 mΩ max.
  • Contact Life: mech'l: 5 million operations min.
  • Operating Time: 5 milliseconds max.
  • Release Time: 5 milliseconds max.

Power Required:

  • 30 mA typical per Relay Energized


  • Operating Temp: 0°C to 70°C (Non-icing)
  • Weight: 14.5 oz

Regulatory Compliance

  • This product is in full compliance with CE requirements.


Part NumberPrice(USD)
View / Download LPCI-IIRO-8 Manual (in .pdf format)
Acquisition Control Communications Engineering / Systems
USA Office

Address: 1480 Gulf Road, Suite 837,
PO Box 1364
Point Roberts, WA 98281

Western Canada - Vancouver BC

Tel:1.800.663.6001 or 1.604.925.6150
Address: 2454 Haywood Ave
West Vancouver, BC V7V 1Y1

Eastern Canada - Markham, Ontario

Tel:1.800.465.0164 or 1.905.513.7027