S
MART
AXIS P
RO
/L
ITE
U
SER
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S
M
ANUAL
FT9Y-B1378 11-7
11: M
ODBUS
C
OMMUNICATION
Processing Requests
The data for Modbus communication are processed between the master and slaves as shown below.
Bit Data at Slaves (Function Codes 01, 02, 05, and 15)
• Master Device Address: Internal Relay
• Master Device Address: Data Register
Word Data at Slaves (Function Codes 03, 04, 06, and 16)
• Master Device Address: Internal Relay
• Master Device Address: Data Register
r
Bit +0
Master
Bit +1
Bit +2
Internal Relay (M)
Bit +0
Slave
Bit +1
Bit +2
Modbus Address
Word +0
b15
Master
Word +1
Word +2
Data Register (D)
b14
...
b1 b0
Bit +0
Slave
Bit +1
Bit +2
Modbus Address
b2
b15 b14
...
b1 b0b2
b15 b14
...
b1 b0b2
Bit +0
+15
Master
Bit +16
Bit +32
Internal Relay (M)
+14
...
+1 +0
Word +0
Slave
Word +1
Word +2
Modbus Address
+2
+31 +30
...
+17 +16+18
+47 +46
...
+33 +32+34
Word +0
b15
Master
Word +1
Word +2
Data Register (D)
b14
...
b1 b0
Word +0
Slave
Word +1
Word +2
Modbus Address
b2
b15 b14
...
b1 b0b2
b15 b14
...
b1 b0b2