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36-Channel PC/104

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Isolated Input/Relay Module



  • 32 Optically Isolated Non-Polarized digital inputs
  • Change of State (COS) Detection
  • Interrupt Sharing
  • 3 to 31 Volt AC or DC Signals
  • Switchable Slow/Fast Filters
  • Schmitt Trigger buffers


  • 4 Form C (NC, NO, C) SPDT Relays
  • Contact ratings 24VDC @ 1A and 115VAC @ 0.5A
  • 5V power with onboard 0.5A resettable fuse for external circuits

Model 104-II32-4RO is a 36-channel PC/104 utility board featuring 32 fully optically isolated digital inputs and four handy relay outputs. The inputs may be driven by either DC sources of 3-31V (or higher by special order) or AC sources at frequencies of 40Hz to 10KHz. Optically isolating the digital inputs from each other, and from the computer, assures smooth, error-free data transmission in noisy, real-world environments. All I/O connections are made via one 34-pin and one 50-pin right angle header (vertical headers available upon request).

Each input circuit includes a jumper selectable slow/fast filter to accommodate AC inputs and is also useful for slow DC inputs in noisy environments. The filter may be manually disabled to increase the boards typical response time to 10 usec when used with faster DC inputs. The input impedance is 1.8K Ohms to accommodate a wide input range. To prevent erroneous input state change detections and interrupts, Schmitt triggers are used which provides a solid logic signal to the computer interface.

The electromechanical relays are more flexible than FET and solid state outputs in regards to the kind of signals that can be switched. Another cool feature of the board is a fused 5V at the connector which can be used with a wrap plug for an easy test setup to quickly verify proper operation of the boards 32 inputs, change of state detection IRQ’s and 4 relays without any additional test equipment!

System interrupts are software controlled, enabling the board to generate an interrupt whenever one or more of the isolated digital inputs changes state. When an interrupt is received a provided ISR (Interrupt Service Routine) handles the request, polls the card once to read the state change then clears the interrupt, enabling the board to detect the next change without processor intervention. IRQ Sharing with other ISA system devices is enabled for ease of system development and installation.

This 8-bit (16-bit pass through connectors) PC/104 board 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-COS), extended (-40 to 85 C) temperature, higher input ranges, without relays, 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 award-winning IE-DAS Embedded System or our rugged E4-DAS Fanless Embedded Computer. For complete details on that and our other fine products then 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.

The 104-II32-4RO is supported for use in most operating systems and includes a free DOS, Linux and Windows 95/98se/Me/NT/2000/XP/2003 compatible software package. This contains sample programs and source code in Visual Basic, Delphi, C Builder, and Visual C for Windows. Also incorporated is a graphical setup program in Windows. Third party support includes a Windows standard dll interface usable from the most popular application programs. Linux support consists of installation files and basic samples for programming from user level via an open source kernel driver.


Isolated Digital Inputs

  • Number and Type: 32, non-polarized, optically isolated from each other and ground
  • Voltage Range: 3 to 31 volts DC or AC Rms ( 40 to 10000 Hz ), CMOS compatible
  • Isolation: 500V*(see manual) channel-to-ground and channel-to channel
  • Input Resistance: 1.8K ohms in series with opto coupler (two LEDs)
  • Response Time: 4.7 mSec w/filter, 10 µSec w/o filter (typical)

Electromechanical Relay Outputs

  • Number of outputs: Four 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: 1 A at 24 VDC ( 30 W max )
  • Switch Voltage / Current: 125 VAC; 60 VDC / @ 1A (max)
  • Contact Resistance: 100 mΩ max
  • Max. Switching Voltage: 125 VA, 60 VDC
  • Max. Switching Current: 1A
  • Contact Life-mechanical: 5,000,000 operations min
  • Operating / Release Time: 5 ms max (mean value: approx 2.5 ms, and 0.9 ms respectively)


  • Generated when inputs change state if enabled by software and jumper selected IRQ
  • IRQ Sharing via tri-stated line driver on jumper selected interrupt line (positive edge true)

Power Required

  • 5 VDC @ 150 mA (all inputs HI & all relays ON, no load on fused 5V power)
  • 5 VDC power is provided via a resettable polyfuse (at 0.5A) for application and general purpose usage


  • Operating Temp: 0° to 70°C
  • Storage Temp: -40° to 80°C
  • Weight: 3.02 oz

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

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