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Basic Operating Procedure Section 1-9
Modbus-RTU Slave Mode
The following example is for the default (standard) communications condi-
tions, with the Modbus slave address set to 1 and the default allocation areas
for Coils, Input Registers, and Holding Registers.
m = D30000 + 100
× unit number
Validate the New Settings Make the new settings in the Setup Area valid by performing one of the follow-
ing.
• Turn the power OFF and then ON again. The Setup Area allocated in the
DM Area will be read when the power is turned ON.
• Restart the Board by turning ON the Inner Board Restart Bit (A60800) or
restart the Unit turning ON one of the CPU Bus Unit Restart Bits (A50100
to A50115, where the bit number corresponds to the unit number). (See
following table.)
• Restart the port on the Serial Communications Board by turning ON one
of the Communications Board Port Settings Change Bits (A63601 for port
1 and A63602 for port 2) or restart the port on the Serial Communications
Unit by tuning ON one of the Communications Unit Port Settings Change
Bits (A620 to A635: The word will be A620 + unit number and the bit will
be bit 01 for port 1 and bit 02 for port 2).
Board
(CS Series only)
Unit
(CS/CJ Series)
Bit Setting Meaning
Port 1 Port 2 Port 1 Port 2
D32000 D32010 m m+10 15 0 Defaults
Parity: Even
Stop bits: 1 bit
Baud rate: 19,200 bps
(Start bits: 1 bit, Data length: 8 bits)
11 to 08 A hex Modbus-RTU slave
D32001 D32011 m+1 m+11 03 to 00 0 hex Disabled for default communications condi-
tions (baud rate: 19,200 bps)
D32006 D32016 m+6 m+16 15 to 08 1 hex Modbus slave address: 1
D32020 D32030 m+20 m+30 07 to 00 0 hex Coils allocation area: CIO Area
D32021 D32031 m+21 m+31 15 to 08 0 hex Input Registers allocation area: CIO Area
07 to 00 0 hex Holding Registers allocation area: DM Area
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