Manual

9: MODBUS TCP COMMUNICATION
9-6 WEB SERVER CPU MODULE USER’S MANUAL FC9Y-B1278
Processing Requests
The data for Modbus communication are processed between the client and servers as shown below.
Bit Data at Servers (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
Internal Relay (M) Modbus Address
Master Slave
Bit +0
Bit +1
Bit +2
Bit +0
Bit +1
Bit +2
Data Register (D)
Modbus Address
Master Slave
Bit +0
Bit +1
Bit +2
Word +0
Word +1
Word +2
b15
b15
b15
b14
b14
b14
...
...
...
b2
b2
b2
b1
b1
b1
b0
b0
b0
Internal Relay (M)
Modbus Address
Master Slave
Bit +0
Bit +16
Bit +32
Word +0
Word +1
Word +2
+31
+47
+14
+30
+46
...
...
...
+2
+18
+34
+1
+17
+33
+0
+16
+32
+15
Data Register (D)
Modbus Address
Master Slave
Word +0
Word +1
Word +2
Word +0
Word +1
Word +2
b15
b15
b15
b14
b14
b14
...
...
...
b2
b2
b2
b1
b1
b1
b0
b0
b0