PURPOSE: To improve the working efficiency of a printer interface circuit by printing out plural pieces of print-out information needed for monitor via a series of operations with high efficiency.

CONSTITUTION: The print-out information to be monitored such as the sensor information, the load information, the sequence program information, the timing chart information, etc. are collectively supplied to a CPU 5 and then stored in a data memory 7 via the CPU 5. When a print-out start signal is supplied from an external input part 8, the CPU 5 sends the 1st print-out information to a sequence controller 1 out of the memory 7 via a communication interface 4. Thus the controller 1 sends the data corresponding to the required print-out information to the CPU 5 via the interface 4.