A method of signal transmission is to be implemented by a control module of an electronic device. The control module includes a first input/output (I/O) port to be coupled to an input module, a second I/O port to be coupled to an output module, and a control unit. In the method, the control unit is configured to electrically interconnect the first I/O port and the second I/O port such that the input module is able to communicate with the output module, or to open a specific channel and to temporarily stop transmission within other channels, based on a signal or instruction received from the input module.