The ComNet FDC8ISOTS1 is an 8-channel optically isolated contact closure transmitter designed for reliable transmission of contact closures over a single optical fiber. It features an eight-channel point-to-point architecture and optically isolated inputs rated at 1500 V to ground, enhancing signal integrity and safety. The microprocessor-based logic supports compliance with NEMA TS-1/TS-2 and Caltrans specifications, ensuring robust performance in demanding environments. The unit supports both stand-alone and rack mount configurations with ComFit interchangeability and includes hot-swappable rack modules, status indicating LEDs, and a DIN-rail mountable form factor with an adaptor plate. It operates across a broad ambient temperature range from -40° C to +75° C.