Omron CP1E CPU UNIT SOFTWARE - Modbus-RTU Easy Master Function; Overview; Flow of Operation

14-11
14 Serial Communications
CP1E CPU Unit Software User’s Manual(W480)
14-4 Modbus-RTU Easy Master Function
14
14-4-1 Overview
14-4 Modbus-RTU Easy Master Function
The Modbus-RTU Easy Master Function can be used only with the CP1E N/NA-type CPU Unit.
Using the Modbus-RTU Easy Master enables easy control of Modbus-compatible slaves, such as
inverters, using serial communications. The serial communications mode is set to Modbus-RTU Easy
Master.
Modbus-RTU commands can be sent simply by turning ON a software switch after setting the Modbus
slave address, function, and data in the DM fixed allocation words for the Modbus-RTU Easy Master.
The response when received is automatically stored in the DM fixed allocation words for the Modbus-
RTU Easy Master.
14-4-1 Overview
14-4-2 Flow of Operation
1
Connect the CP1E CPU Unit and Modbus-RTU Slave
using RS-422A/485 ports.
2
Select Built-in RS232C Port or Serial Option Port in the
PLC Setup and transfer the PLC Setup from the CX-Pro-
grammer to the CP1E CPU Unit. (Set the serial communi-
cations mode to Modbus Easy Master, and set the
communications conditions.)
3
• Set the Modbus-RTU frame in the DM Fixed Allocation
Words.
• Turn ON the Modbus-RTU Master Execution Bit
(A640.00 or A641.00).
Modbus-RTU
15 08 07 00
D1200
--
D1201
--
D1202
D1203
Communications are easily achieved
by simply turning ON A640.00 after
setting the Modbus-RTU command in
the DM fixed allocation words.
Modbus-RTU Master Execution
Bit for Port 1 A640.00
CP1E N/NA-type CPU Unit
Slave address
Slave address
Slave address
Function code
Function code
Function code
Communications data
Communications data
Communications data
OMRON Inverters
3G3JX, 3G3MX, 3G3RX,
3G3JV, 3G3MV, or 3G3RV
Number of communications data bytes
~
Wiring communications
PLC Setup
Create
ladder
Program
Cyclic tasks
Interrupt tasks