Model WM-IIRO-8 intelligent 8-bit parallel digital I/O module offers 8 Form C SPDT electromechanical relays and 8 optically isolated digital inputs with change-of-state interrupt generation. It communicates with wireless serial modem via 900 MHz connection at distances up to 7 miles line-of-sight, 20 miles with optional antenna. The 8 isolated inputs are driven by dc sources of 3-28 V or ac sources at frequencies of 40 Hz to 10 kHz, and are not polarity sensitive.