Rockwell Automation 1747-L40 SLC 500 Fixed Hardware Style - Manual (Page 94)

Chapter 8
Troubleshooting
8–3
Replacing Fuses
When replacing a fuse, be sure to remove all power from the system.
Program Alteration
There are several causes of alteration to the user program, including extreme
environmental conditions, Electromagnetic Interference (EMI), improper
grounding, improper wiring connections, and unauthorized tampering. If you
suspect the memory has been altered, check the program against a previously
saved program on an EEPROM, UVPROM or Flash EPROM module.
To receive the maximum benefit of this troubleshooting section, we
recommend you follow these steps:
1. Match your processor LEDs with the status LEDs located in the first
column in the tables on the following pages.
2. Once the status LEDs are matched to the appropriate table, simply move
across the table identifying error description and probable causes.
3. Follow the recommended action steps for each probable cause until the
cause is identified.
4. If recommended actions do not identify the cause, contact your local
Allen–Bradley sales office or distributor.
Troubleshooting Your Fixed
Controller