Omron 3G3RX Series, User Manual

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4-158
4-4 Communication Function
4
Functions
ModBus-RTU Method
Follow the procedures below in regards to communication between the external controller and the
Inverter.
(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.
Response from the Inverter (Frame 2) is output as return after the Inverter receives the query
(Frame 1), not output independently.
External controller
Inverter
(1)
(2)
(1)
Wait time (silent in C078)
(3) Communication error timeout C077
(Operates according to
communication error selection
C076 when reception times out.)
Time
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.
⎯