IAI America SCON-C - Manual (Page 240)

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Appendix
5.6 Specific Problems
 I/O signals cannot be exchanged with the PLC.
Cause: [1] The 24-V I/O power supply is connected in reverse.
(In this case, the input circuits are not affected, but the output circuits will be damaged.)
[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.
 The ALM lamp illuminates when the power is input.
(An alarm is present.)
* An alarm is present. Connect the PC or teaching pendant, check the nature of the alarm, and remove the
cause.
 The EMG lamp illuminates when the power is turned on.
(This condition indicates that an emergency stop is actuated.)
[1] Check if the emergency stop switch on the operation panel is depressed.
[2] Check if pin 4 (EMG-) of the system I/O connector is unconnected.
(Refer to 2.2, “Name and Function of Each Part.”)
 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] The operation mode status is “MANU.”
[3] 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.