- - - - - - - - - - - - - - - - - - - - - MELSEC·A
This section describes various procedures for establishing the nature of any
faults, and corrective action.
System reliability depends not only on reliable equipment but also on short
down-time in the event of faults.
The basic points to be kept in mind in troubleshooting are the following
(1) Visual checks
Check the following points.
(a) Machine motions (in stop and operating statuses)
(b) ON or OFF of power
(c) Status of I/O devices
(d) Condition of wiring (I/O wires, cables)
(e) Display states of various indicators (such as POWER LED, RUN
LED, and ERROR LED)
(t) States of various setting switches (such as extension base and
power failure compensation)
After checking (a) to (t), connect the peripheral devices and check the
running status of PC and the contents of program.
(2) Trouble check
Observe any changes in the error condition during the following.
(a) Set the RUN keyswitch to the ·STOP· position.
(b) Perform reset by the RESET keyswitch.
(c) Turn the power on and off.
(3) Narrow down the possible causes of the trouble.
Deduce where the fault lies i.e:
(a) Inside of outside of PC.
(b) I/O modules or other modules.
(c) Sequence program.