Network Device and Communication Method

A communication method implemented by a network device, wherein the communication method comprises:

• controlling a current conversion circuit of a hybrid interface circuit of the network device to output a probe current, wherein probe current comp i sinusoidal alternating current or a direct current less than a minimum value in a current range in an analog input (AI) mode;
• detecting, using a detection circuit of the hybrid interface circuit, a voltage at the hybrid interface;
• determining, based on the voltage, whether an interface of an instrument device is in the AI mode;
• controlling the hybrid interface circuit to operate in an analog out (AO) when the in ace is in the AI mode;
• controlling the current conversion circuit to output a first current in a power over data line (PoDL) mode when the interface is not in the AI mode;
• detecting, using the detection circuit, a voltage range at the hybrid interface;
• determining, based on the voltage range whether the interface is in the PoDL mode;
• controlling the hybrid interface circuit to operate in the PoDL mode when the interface is in the PoDL mode;
• controlling the current conversion circuit to output a second current in the AO mode when the interface is not in the PoDL mode;
• detecting, using the detection circuit a changing voltage at the hybrid interface;
• determining, based on the changing voltage, whether the interface is in the AO mode;
• and
• controlling the hybrid interface circuit to operate in the AI mode when the interface is in the AO mode.