Communication 
 
FPΣ User's Manual 
244 
8.8  Modbus RTU Communication 
The Modbus RTU protocol enables the communication between the FPΣ and other devices 
(including the Panasonic FP-e PLCs, touch terminals of the GT series and KT temperature 
controllers). The master station sends instructions (command messages) to the slave stations 
and the slave stations respond (send response messages) based on the instructions received. 
The master station has read and write access to a maximum number of 99 slave stations. 
 
 
Modbus RTU connection between the FPΣ and an external device 
1
 
Command message 
2
Response message 
 
NOTE
 
The Modbus protocol supports both ASCII mode and RTU binary mode. 
However, the PLCs of the FP Series only support the RTU binary mode. 
Modbus RTU master function 
Write and read access to various slaves is possible using the F145_WRITE and F146_READ 
instructions. Individual access to each slave as well as global transmission is possible. 
FP-e
FP-e
FP-X
KT KT
FP Σ
 
1
 
Master 
2
 
Slave