PCI-IDI-xx Series cards provide individual-input optical isolation and accept as many as 48 parallel differential digital inputs at voltages up to 31VDC. The inputs are connected to two light emitting diodes in parallel avoiding polarity sensitivity. These cards provide a much lower cost per point than externally-mounted, optically-isolated, solid-state modules or PLCs. Input connections are via ribbon-cable headers on the card and a tie-down bar is included to provide strain relief for those cables.
PCI-IDI Series cards are especially useful in applications where high-common-mode external voltages are present as found in factory automation, energy management, security systems, and process monitoring applications. In addition to protecting your computer from accidental contact with high external voltages, the isolation provided eliminates troublesome ground loops.
There are 48-bit, 32-bit, and 16-bit versions. The latter two models are de-populated versions of the 48-bit card.
The change-of-state (COS) interrupt capability (denoted by a "C" after the model number) provides a means to automatically interrupt the host computer in real time. When one or more input bits change state, latched interrupt requests are generated. That interrupt, in turn, can be used by your application program to initiate a poll of the inputs, then signal appropriate alarms, and/or initiate scan of other I/O points that have not been previously activated. This can greatly simplify your application program and eliminate need to continuously poll inputs.
COS interrupt is enabled/disabled for all 3 groups of 16 bits. Each group of 16 bits has 2 interrupt bits (within the base+7 register) to indicate whether the COS occurred on the lower (0-7) or upper (8-15) bits.
