This PCIe-IIRO-16 is a x1 lane PCIe isolated digital input and relay output board with Change of State (COS) detection capabilities. The isolated inputs can be driven by either AC or DC and are not polarity sensitive. Input signals are rectified by a diode bridge and applied to the inputs of opto-isolators. A 1.8k ohm resistor in series provides current limiting. Standard 12/24 AC control transmitter outputs can be accepted as well as DC voltages. The input voltage range is 3V to 31VDC (or 40-10kHz RMS). To extend the input voltage range, you may connect external resistors in series. The electro-mechanical relay outputs of the PCIe-IIRO-16 are comprised of ten form C SPDT outputs and six form A SPST (normally-open) type. The relays are all de-energized at power-on. Data to the relays is latched. I/O wiring connections for this board are via a 78-pin D-sub connector. A molded round-wire “Y” cable is typically used to connect this card to termination panels with two 37-pin D-sub connectors.