27 TROUBLESHOOTING
27.1 Checking Module Status
453
27
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.
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.
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
: 0619 command
*1 When performing communication test with 2C/3C/4C frame, refer to the following manual.
MELSEC Communication Protocol Reference Manual
Parameter setting item Setting contents
Communication protocol setting MC protocol (Format 1)
Communication speed setting 9600 bps
Transmission setting Operation setting Independent
Data bit 7
Parity bit Yes
Odd/even parity Odd
Stop bit 1
Sum check code Yes
Online change Disable
Setting change Disable
Station number setting 0
To Next Page
Loading...
