| 摘要 |
PROBLEM TO BE SOLVED: To perform the connection check of a device without using a dedicated hard line for connection check for the device by providing a detecting means detecting the connection state of the device by using a prescribed communication channel. SOLUTION: The CPU 401 of a main control substrate 901 first instructs a communication controller 402 to perform reset frame transmission when power is supplied, and each slave communication IC is made to be in a reset state. After that, the CPU 401 instructs the controller 402 to perform connection check. Then, the controller 402 individually transmits a connection check signal to three serial lines. Since the three slave communication ICs (addresses 7 to 5) should be connected to the line of a paper feeding side, in the case returned data is to be '00011111', the connection is decided as normal, and when a value other than the above value is returned, the connection is decided as abnormal to define the connection as an error state, and all image formation operations are inhibited.
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