PURPOSE: To connect a printer to any type of high-order devices by installing a data buffer to the printer device and variably controlling a BUSY signal outputting period, during which a BUSY signal is outputted to a high-order device, depending on the number of printing data stored in the data buffer.

CONSTITUTION: A microcomputer (μCM) 3 installed to a printer device 2 stores printing data in a data buffer memory 5 by controlling an input-output controlling section 4 when receiving printing data from a high-order device 1. The memory 5 has a capacity which is sufficient to store printing data of plural lines by considering the shortest time-out time of the high-order device 1, the minimum time of the printer device 2 for receiving 1-byte printing data, and the maximum time required after starting the printing of the 1st line until the next line printing is started. The μCM3 variably controls a BUSY signal outputting period outputted to the device 1 depending on the number of printing data stored in the memory 5. In such a way, the occurrence of time-out in a normal operation time is suppressed even when the printer device is connected with any type of higher rank devices.