12: M
ODBUS
ASCII/RTU C
OMMUNICATION
12-8
FC5A M
ICRO
S
MART
U
SER
’
S
M
ANUAL
FC9Y-B1268
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
Bit +0
Master
Bit +1
Bit +2
Internal Relay (M)
Bit +0
Slave
Bit +1
Bit +2
Modbus Address
Master Device Address: Data Register
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
b0
b2
b15 b14
. . .
b1
b0
b2
Word Data at Slaves (Function Codes 03, 04, 06, and 16)
Master Device Address: Internal Relay
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
Master Device Address: Data Register
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
b0
b2
b15 b14
. . .
b1
b0
b2
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