Loopback Test - Mitsubishi Electric MELSEC iQ-R Series User Manual

Loopback test

A loopback test is a test to perform communication with the loopback test function of the MC protocol in order to check the
connection between C24 and the target device, the communication function of each device, and the operation of the
communication program of the target device.
Operating procedure
1.
Connecting C24 to a target device
Turn OFF the power for the station with C24 and connect a communication cable to communicate with the target device in
order to perform data communication using the MC protocol.
MELSEC iQ-R Serial Communication Module User's Manual (Startup)
2.
Setting the parameter with Engineering tool
• Configure the parameter settings with Engineering tool, and write the parameters to the CPU module in order to perform
data communication using the MC protocol.
• The following shows an example of the settings when performing the loopback test on the interface on the CH1 side.
Parameter setting item
Communication protocol setting
Communication speed setting
Transmission setting
Station number setting
3.
Performing loopback test
• By restarting or resetting the CPU module, the communication is enabled in approximately one second. (Set the CPU
module in the STOP state.)
• Create a program for the loopback test on the target device side and send a command message as shown below to C24.
For communication test with 1C frame: TT command
For communication test with 2C/3C/4C frame
*1 When performing communication test with 2C/3C/4C frame, refer to the following manual.
 MELSEC Communication Protocol Reference Manual
Operation setting
Data bit
Parity bit
Odd/even parity
Stop bit
Sum check code
Online change
Setting change
*1
: 0619 command
Setting contents
MC protocol (Format 1)
9600 bps
Independent
7
Yes
Odd
1
Yes
Disable
Disable
0
27 TROUBLESHOOTING
27.1 Checking Module Status
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