PURPOSE: To collect and transmit/receive many pieces of ON/OFF or work information, by providing a multi-spot processing function, a series-parallel or parallel-series converting functions, and a light emitting-photodetecting function to the transmitting and receiving parts.

CONSTITUTION: A transmitting part contains (n) units of input terminals 5, (m) units of parallel gate circuits 6, a selector circuit 9 which scans successively the circuit 5, and a parallel-serial conversion synchronizing circuit 13 respectively. The circuit 9 is driven by an n-notation counter 10 which counts the clocks supplied from a quartz oscillator part 11. Then the circuit 9 transmits the ON/ OFF or word information given from (n) units of input terminals to an optical cable 17 via the circuit 13, At the receiving side, the output is successively supplied to (n) units of (d) output terminals after carrying out the processing opposite to that of the transmitting part.