Self-Diagnostics Test; Self-Loopback Test - Mitsubishi MELSEC-A Series Reference Manual

8. PROCEDURES TO OPERATION
8.7

Self-diagnostics Test

(1) The self-diagnostics test checks link module hardware and link cables for wire break.
The following five items are checked with the self-diagnostics test:
Test name
Forward loop test
Reverse loop test
Station-to-station test
(Testing station)
Station-to-station test
(Tested station)

Self-loopback test

8.7.1 Self-loopback test
(1) Self-loopback test
(a) The self-loopback test checks the hardware of each link module, including the
(b) When the receive end cannot receive data sent from the send end in a given
For optical fiber cable
For coaxial cables
Description
Checks optical fiber cables or coaxial cables in the entire data link
system. This test also checks the forward loop, through which
data link is usually performed.
Checks optical fiber cables or coaxial cables in the entire data link
system. This test also checks the reverse loop, which is used for
loopback in the event of an error.
Checks line connection between two stations, by setting the
lower-numbered station as the testing station and another station
as the tested station.
Checks the hardware of each link module, including
the transmission and receive circuits.
transmission and receiving circuits in transmission system.
1) In the MELSECNET data link system, connect the send and receive ends on
the host station with an optical fiber cable or coaxial cables as shown in Fig
8.13.
2) In the MELSECNET/B data link system, perform this test to a single link
module.
(Connecting SDA/RDA and SDB/RDB are not required.)
time, the loop is determined to be faulty.
MELSECNET mode MELSECNET
MELSECNET
MELSECNET
Operating Mode
mode
mode
Applicability
Fig 8.13 Self-loopback test
8 - 17
MELSECNET/B
MELSECNET
MELSECNET MELSECNET MELSECNET
composite mode mode mode composite mode
MELSECNET MELSECNET/B
: Executable, : Not executable