The PCLD-786 is an SSR I/O module carrier board that can accept up to eight photo-coupler isolated solid state relay modules and drive up to eight external relays. It is designed as an accessory board for any PC-LabCard equipped with 16 digital outputs on a standard 20-pin connector. The PCLD-786 accepts up to eight Opto-22 compatible AC or DC SSR (solid state relay) modules in any combination. An AC module always turns its output on at the zero cross voltage point, thus avoiding transient problems caused by heavy inductive loads. DC modules provide fast and bounce-free DC power switching. Compared to mechanical relays, SSRs are more reliable, respond quicker and are more resistant to noise. The PCLD-786 has eight digital output drivers for external relays. Driving voltages are jumper selectable for 5 V, 12 V or external DC power (if overloading a PC power supply is a concern). Each module or driver is equipped with an adjacent red LED for status monitoring.