Mitsubishi MELSEC-A Series Reference Manual page 241

8. PROCEDURES TO OPERATION
(2)
(3)
Test procedure
The following flowchart shows the operation procedure for self-loopback test.
Test result
The LEDs on the link module indicate the test result.
The descriptions of the LEDs are as follows.
(a) Normal....... The following LEDs flash in order:
CRC, OVER, AB.IF, TIME, DATA, UNDER
(b) Error...........The corresponding LEDs turn ON and the test is discontinued.
1) When the F.LOOP, R.LOOP and TIME LEDs turn ON:
a) The forward loop cable is broken.
b)The sending and receiving ends of the forward loop are not
connected with a cable.
c) The sending end of the forward loop is connected to the
sending end of the reverse loop, and the receiving end of the
forward loop is connected to the receiving end of the reverse
loop.
(2) When the F.LOOP, R.LOOP, and DATA LEDs turn ON:
a)The reverse loop cable is broken.
b)The sending and receiving ends of the reverse loop are not
connected with a cable.
(3) When an ERROR LED other than 1) and 2) turns ON:
a)Hardware error
b)The cable was disconnected during the test.
c) A cable was broken during the test.
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