4-4 Communication Function Modbus-RTU Method Follow the procedures below in regards to communication between the external controller and the Inverter. (1) (1) External controller Inverter Time Wait time (silent interval + C078) (3) Communication error timeout C077 (Operates according to communication error selection C076 when reception times out.) (2) 4 (1) : Frame to be sent from the external control device to the Inverter (Query) (2) : Frame to be returned from the Inverter to the external controller (Response) (3) :
Unless the Inverter completes reception of a query from the host within the time set in C077 after the Inverter completes a response (response transmission), the Inverter becomes ready to receive the first data again. In this case, the Inverter sends no response. Also, the Inverter's operation conforms to the setting of communication error selection C076. For details, refer to the following table. The receiving timeout monitor starts after the first transmission/reception is performed after power-on or reset. Receiving timeout is inactive until reception or transmission is performed.
Functions Response from the Inverter (Frame 2) is output as return after the Inverter receives the query (Frame 1), not output independently. 4-154 Parameter No. Function name Data Default setting Unit C076 Communication error selection 00: Trip (Trip after receiving timeout [E41]) 01: Trip after stop (Deceleration stop after receiving timeout. Trip after stop [E41]) 02: Ignored (No trip and no alarm output) 03: FRS (Free-run stop after receiving timeout. No trip and no alarm output) 04: Deceleration stop (Deceleration stop after receiving timeout. No trip and no alarm output) 02 C077 Communication error timeout 0.00 to 99.99:
Time before receiving timeout 0.00 C078 Communication wait time 0. to 1000.: Wait time until response starts after reception is completed (excluding silent interval) 0.