PURPOSE: To process an emergency signal at a higher speed by connecting mutually terminal input/output sections transmitting/receiving the emergency signal via a hardware logic circuit in a network system having an emergency signal processing function.

CONSTITUTION: Suppose that an emergency stop limit switch LS of a terminal device T1 is activated. A signal from a limit switch LS is coded via an input module 33 and it is subjected to logical operation by a gate array 17 via an input signal line 21. The activated limit switch LS is grasped by the logical operation to select an actuator to be stopped emergently. Suppose that a terminal device T2 is a machine tool operated in interlocking with the terminal device T1 for example, the gate array 17 applies logical operation to stop emergently the interlocking device and transmits a signal representing it to an output module 35. The output module 35 decodes the signal to activate a relay RL or an electromagnetic coil MC interlocked with a prescribed actuator.