PURPOSE: To reduce the load of processor and to increase the processing ability of the entire system, by informing a central processing unit of a time division type electronic exchanger of the status change of an individual line signal exclusively when the status is changed and making unnecessary the repetition of useless scanning when a change is not present.

CONSTITUTION: Each subscriber 1 is connected to a multiplexer 3 via a relay exchanger 2, and a time division switch network 5 is connected to this device 3 via highways 40∼4n. Bits representing the individual line signals of the highways are picked up with the network 5 and they are connected by one to one to individual line signal detectors 60∼6n per the highways. The individual line signal is received at a cable receiver 7 of the devices 60∼6n to store it in a memory 8. The content of the memory 8 is stored in the 2nd memory 10 and the memory 8 and the content of the memory 10 before a specified time are compared at a comparison circuit 9, it is informed to a CPU13 only when the status of the individual line signal is changed to reduce the load of the CPU13.