PURPOSE: To perform test printing without fail prior to the reception of normal data, by inhibiting data transmission from a center automatically until the completion of the test printing even when a power source is turned on.

CONSTITUTION: A terminal controller 2 is provided with a control part 21, a buffer 22, a circuit control part 23, etc., and data DATA from a center 3 is sent to a printer 1 via the circuit control part 23 and buffer 22. Once receiving a select (SELECT) signal from the center 3, the circuit control part 23 returns a wait (WAK) or ready-for-reception (READY) signal according to whether reception is enabled or not, but a request SI signal is OR-ed with the full signal of a buffer 22 to generate a WAK signal, thereby enqueuing the data transmission of the center 3. Further, when the buffer 22 is empty and there is no request SI, the READY is sent back.