Special function unit with interrupt latches for programmable controller

A special function unit for a programmable controller, which controls external equipments in response to at least one controller output signal from said programmable controller, said special function unit comprising:

• plural flip-flop means, each for latching a respective one of said controller output signals from said programmable controller and providing a respective latch output signal;
• OR circuit means for generating an interruption input signal in response to each of said latch output signals from said flip-flop means;
• an input circuit for distinquishing among said controller output signals latched in said flip-flop means;
• an output circuit for resetting said flip-flop means;
• a microprocessor for performing an interruption processing according to said interruption input signal and an output of said input circuit in order to control said external equipments through an external equipment interface, and after the interruption processing, said microprocessor generating a reset control signal to said output circuit to reset said flip-flop means.