9
.
Program
38
9.1.1. Outline of Processing
The following figure shows the data flow from when PLC (SCU) issues command data to
Destination Device by using serial communications (Modbus-RTU communication) until when
it receives the response data from Destination Device.
(1)The ladder program executes the deliver command instruction (CMND instruction) for
which Modbus-RTU communication is specified.
(2)The command data of Total Power ON Time Monitor is sent to Inverter by Modbus-RTU
communication.
(3)The Inverter executes the command by receiving the command data from PLC and returns
the response data to PLC.
(4)The PLC receives the response data from Inverter and stores in the specified address.
PLC
RS-485
Inverter
CPU Unit
Serial Communications Unit
Ladder program
CIO 5020 to 5023
Command Data
setting area
Serial Gateway
function
Command data
Response data
From CIO 5500
Response data
storage area
(2)Sends the command data
(Modbus-RTU communication)
(3)Executes the
command and
returns the
response data.
(4)Receives the
response data and
stores it in the
specified memory.
CMND
(1) Executes the send
command instruction.
(CMND Instruction)
(The Modbus-RTU
Communication is specified.)
Summary of Contents for CJ2*-CPU Series
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