Mitsubishi Electronics A1SJ71AP23Q ユーザーズマニュアル

5

5.5.3

Forward loop test/reverse loop test

The forward loop test/reverse loop test checks a forward or reverse loop side line of the 
MELSECNET after connecting all stations via a cable. (Not provided for the 
MELSECNET/B data link system)

 • Forward loop test

The line is judged by whether the data sent from a forward loop send side of the 
master station can be received by a forward loop receive side of the master 
station.

 • Reverse loop test

The line is judged by whether the data sent from a reverse loop send side of the 
master station can be received by a reverse loop receive side of the master 
station.

(1) Execute a forward or reverse loop line test, setting a Q series local station to 

the RUN status (Y10=ON).
If the test is conducted in STOP status (Y10=OFF), the master station treats 
the Q series local station as a faulty station (relevant bit in D9228 to D9231 is 
turned ON).However, the test is normally conducted.

(2) Set link parameters for the master station when executing a forward or 

reverse loop back test.(At least set the total number of slave stations)

(a) MELSECNET(A1SJ71AP23Q)

An optical fiber cable connects the OUT and IN of all stations.

Master station

Station

No.02

Station

No.01

Station

No.00

OUT

IN

Local station

No.1

Local station

No.2

OUT

IN

OUT

IN

Front

Front

Front

Data flow of forward loop

Data flow of reverse loop

Optical fiber
cable

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