This main board is the main control of gyro system. Two ship supply input to mainboard. One AC supply output 26Vac from  transformer which step down AC ship supply from 230Vac or 115Vac via link and other 24Vdc direct from ship 24V breaker as backup supply. All serial data output will connect to main PCB via J5 to J7 socket. All input will connect between J1 and J4.