Modbus-Rtu Easy Master Function; Overview; Flow Of Operation - Omron CP1E CPU UNIT SOFTWARE User Manual

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.

14-4-1 Overview

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.
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
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.

14-4-2 Flow of Operation

1
Wiring communications
2
3
Create
ladder
Program
CP1E CPU Unit Software User's Manual(W480)
CP1E N/NA-type CPU Unit
Connect the CP1E CPU Unit and Modbus-RTU Slave
using RS-422A/485 ports.
Select Built-in RS232C Port or Serial Option Port in the
PLC Setup
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.)
• Set the Modbus-RTU frame in the DM Fixed Allocation
Cyclic tasks
• Turn ON the Modbus-RTU Master Execution Bit
Interrupt tasks
14 Serial Communications
15 08 07
Slave address
D1200 - -
D1201 - - Function code
Number of communications data bytes
D1202
D1203
Communications data
Slave address Function code
Slave address Function code
Modbus-RTU
Words.
(A640.00 or A641.00).
00
Communications data
Communications data
OMRON Inverters
3G3JX, 3G3MX, 3G3RX,
3G3JV, 3G3MV, or 3G3RV
14-11
14