Abstract: A transmission timing control section latches operational data received from an operating section in timing corresponding to a channel set in a channel setting section, compares the latched operational data and last operational data stored in a temporarily storage section and judges whether or not the latched operational data is identical with the last operational data. In case of the judgment for those to be identical with each other, no transmission instructing signal is outputted, and the transmission of the communication data is stopped in that timing. In case of the judgment for those not to be identical with each other, a transmission instructing signal is outputted from the transmission timing control section to a transmitting section to transmit the communication data in that timing.