Mitsubishi MELSEC LJ71C24, User Manual

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6 SETTING AND WIRING
6.4.2 Self-loopback test
The Self-loopback test checks the communication between the C24 and CPU modules
and the operation of the communication function of the C24.
Also, tests two interfaces of the C24 at once.
Follow the procedure below to perform an Self-loopback test.
(Procedure 1) Connecting cable
Connect cables to two interfaces as follows.
• Connect cables to the RS-232 interface within the connector and install it to the
interface.
• Connect cables to the RS-422/485 interface on a terminal block.
(Procedure 2) Communication protocol setting and transmission setting (refer to Section 7.3)
(1) In the switch setting, set the communication protocol setting of both interfaces to
"Self-loopback test".
(2) Set transmission settings and communication rate setting of the two interfaces
according to the transmission specification for data communication with an
external device.
(3) Set the CPU module to STOP status and write the parameters to the
Programmable controller.
(Procedure 3) Performing the Self-loopback test
Restart or reset the CPU module. The test starts automatically in about one second.
(Set the CPU module to STOP status.)