8-2
Chapter 8. Modbus Communication Function
• These items can be displayed and configured if a model with RS-485
communication is used.
• When the communication type is set to MODBUS/RTU, the operation is fixed to
8-bit data regardless of the data format (data length) setting.
Handling Precautions:
• The settings can be configured using the keys on this device or using
Smart Loader Package model SLP-C1F. RS-485 communications cannot be
used for configuration.
Communication procedure
The communication procedure is as follows.
(1) The host device (master station) sends an instruction message to one C1M
unit (slave station).
(2) The slave station receives the instruction message and performs read or write
processing according to the content of the message.
(3) The slave station sends a response message appropriate for the type of
processing.
(4) The master station receives the response message.
Handling Precautions:
• Sending data using several protocols intermixed (CPL, Modbus/ASCII,
Modbus/RTU, PLC link) to the same RS-485 transmission line is not
allowed.
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