Specifications

10–2 Troubleshooting
Publication 1747-6.2
When troubleshooting, pay careful attention to these general
warnings:
!
ATTENTION: Have all personnel remain clear of the
controller and equipment when power is applied. The
problem may be intermittent and sudden unexpected
machine motion could result in injury. Have someone
ready to operate an emergency-stop switch in case it
becomes necessary to shut off power to the controller
equipment. Also, see NFPA 70E Part II for additional
guidelines for safety related work practices.
Never reach into a machine to actuate a switch since
unexpected machine motion can occur and cause
injury.
Remove all electrical power at the main power
disconnect switches before checking electrical
connections or inputs/outputs causing machine motion.
If installation and start-up procedures detailed in chapters 6, 7, and 8
were followed closely, your SLC controller will give you reliable
service. If a problem should occur, the first step in the
troubleshooting procedure is to identify the problem and its source.
The SLC 500 controller has been designed to simplify
troubleshooting procedures. By observing the diagnostic indicators
on the front of the power supply, processor unit and I/O modules, the
majority of faults can be located and corrected. These indicators,
along with error codes identified in the programming device user
manual and programmer’s monitor, help trace the source of the fault
to the user’s input/output devices, wiring, or the controller.
Removing Power
Before working on a SLC 500 modular system, always remove the
power supply input power at the main power disconnect switch.
The power LED on the power supply indicates that DC power is
being supplied to the chassis. The LED could be off when incoming
power is present.
Tips for Troubleshooting
Your Control System