Manual

159
10. Troubleshooting
10.6 Specific Problems
z I/O signals cannot be exchanged with the PLC.
Cause: [1] The 24-V I/O power supply is connected in reverse.
[2] If the problem is with an output circuit, a circuit component may have been damaged due to a
large load that caused the current flowing into the circuit to exceed the maximum current.
[3] Contact failure in the connector or relay terminal block on the PLC end.
[4] Contact failure between the female pins in the flat cable connector and the male pins on the
controller due to expanded female pins.
Action: Check the connection condition of the power supply and connector, as well as the load on the
output side.
If the cause is identified as [1] or [2], the controller must be replaced. If there is a possibility of [4],
the flat cable must be replaced. Please contact IAI.
Warning: When performing a continuity check of the flat cable, pay due attention not to expand
the female pins in the connector. It may cause contact failure and disable normal
operation of the controller.
z The ALM lamp illuminates when the power is input.
(An alarm is present, or an emergency stop has been actuated or the motor power cut off.)
* If the ALM output signal is OFF, an alarm is present. Connect a PC or teaching pendant to check the
nature of the error and then remove the cause.
* If the ALM output signal is ON, the emergency stop circuit has been actuated. Check the following points,
among others:
[1] Is the emergency-stop switch on the operation panel pressed or any necessary interlock released?
[2] Is the emergency-stop switch on the teaching pendant pressed?
[3] If multiple controllers are connected, is the crossover wiring correct?
z The SV lamp does not illuminate when the servo ON signal is input after the power was input.
(The servo does not turn ON.)
Cause: [1] Contact failure of the flat cable
[2] Faulty controller
Check the servo ON signal (SON) on the I/O monitor screen of the PC or teaching pendant.
If the signal is input, probably the controller is faulty. Please contact IAI.
[3] Is parameter No. 42 (Enable function) enabled by mistake by connecting a teaching pendant not
supporting the enable switch?