PURPOSE: To prevent the defect of data and to eliminate the temporary interruption of monitoring, talking operations by preserving information which is not displayed periodically in a memory according to an operator's hard copy request in an event, and reproducing it at the time of necessity.

CONSTITUTION: Hard copy information automatic recording means 7 stores a hard copy information automatic recording timing requested by a talking unit 1 in an internal memory. A plant signal for discriminating the recording timing of stored automatic recording data is input, and when the timing holds, a hard copy information preservation request is notified to hard copy information preserving means 8. The means 8 inputs display screen information and preserves it in a memory 10 when a hard copy information preservation request is delivered from the means 7. Hard copy information reproducing means 9 reads out the information preserved in the memory 10 by a hard copy information reproduction request requested by the unit 1, and starts a write hard copy unit 5 in the memory of a hard copying unit 5 to hard copy it.