Rockwell Automation 1775-MX_S4A,D17756.3.1 User Manual PLC-3 BACKUP CONC(OR.DU1 - Manual (Page 108)

Diagnosing Faults
Chapter 6
6-4
Table 6.B
Status Indicators for Backup Processor
Indicator Status Description
PROCESSOR GREEN Backup processor is active (normal operation in backup
mode)
RED Major fault occurred
OFF Power is off in the backup processor
OUTPUTS GREEN Not used
RED Major fault*
OFF Backup mode
PROGRAM GREEN Backup processor is in program load mode
RED Major fault 1
OFF Backup processor is not in program load mode
ACCESS GREEN A peripheral device is connected to a peripheral
communication channel and is onĆline (channel active).
RED A peripheral device is editing the program or major fault 1
OFF No peripheral communication channels are active.
1. When automatic switchover is selected, a major fault will turn all four status indicators red.
Diagnosing Faults with Module Status Indicators
All PLC-3 modules have two self-test indicators. Table 6.C describes how
to interpret these indicators.
Table 6.C
Module SelfĆTest Indicators
Indicator & Status
PASS FAIL Description
ON OFF Normal operation
OFF ON Module fault
ON ON PowerĆup or system reset
OFF OFF Processor shut off
Most PLC-3 modules have one or more indicators to help you pinpoint the
location of a fault. (See Figure 6.2 through Figure 6.4) Table 6.D through
Table 6.F describe how to interpret the indicators on each module.