Common communication faults include the following:

•        No response is returned.

•        The VFD returns an exception response.

Possible causes of no response include the following:

•        The serial port is set incorrectly. For example, the converter uses the serial port COM1, but COM2 is selected for the communication.

•        The settings of the baud rates, data bits, end bits, and check bits are inconsistent with those set on the VFD.

•        The positive pole (+) and negative pole (-) of the RS485 bus are connected reversely.

•        The resistor connected to RS485 terminals on the terminal block of the VFD is set incorrectly.