Azbil F4Q, User Manual

Page: 35 / 76

5-1
Chapter 5. Modbus Communication (RTU Mode)
5 - 1 Communication Procedure
The following is the RS-485 communication procedure in its simple form:
(1) The master station sends an instruction message to slave stations specifying
the station it wishes to communicate with.
(2) The slave station receives the instruction message, and performs read or write
processing according to the content of the message.
(3) Also, the slave station sends a message corresponding to the processing
content as a response message.
(4) The master station receives the response message.