Loop Test (Optical Loop System Only) - Mitsubishi Electric Melsec QJ71LP21 Reference Manual

4 SETUP AND PROCEDURES BEFORE STARTING THE OPERATION

4.8.1 Loop test (optical loop system only)

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This test checks the line status of the forward and reverse loops upon completion of
the wiring of the optical loop system. Also, when a loopback is being executed, it
checks the station that executes the loopback.
For example, in the system shown below, where the IN/OUT connectors of station
number 5 are connected in reverse, conduct a loop test using GX Developer
connected to station number 1.
The monitor screen shown below appears after the loop test has been executed, and
station No. 5 is detected as the station with a receiving direction error.
GX Developer
OUT
POINT
In the loop test, data link is stopped to check the wiring status.
To check the wiring status without stopping data link, check the status of SW009C
to 009F.
Refer to Section 8.2.10 for details.
Reserved station
Station Station
No. 1 No. 3
IN OUT IN OUT
IN OUT IN
Station
Station
No. 8 No. 7
Loopback
Station Station
No. 6 No. 4
IN OUT IN OUT
OUT IN IN OUT
Station Station
No. 2 No. 5
Loopback Faulty station
MELSEC-Q
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