User Manual PLC-3 FAMILY I/0 Instruction Manual

Diagnostics Methods
Chapter 7
7-6
All PLC-3 modules have two self-test indicators. Table 7.A describes how
to interpret these indicators.
Table 7.A
Module
Selftest Indicators
Indicator and Status
PASS FAIL
Description
ON OFF Normal operation
OFF ON Module fault
ON ON Powerup or system reset
OFF OFF Processor shut off
The scanner modules have several indicators to monitor its status
(see Figure 7.3).
Figure 7.3
Indicator
Locations for 1775S5 and 1775SR5 Scanner Modules
PASS and FAIL indicators
Thumbwheel switch
Forces enabled indicator
I/O channel
status indicators
DH/DH+
status indictors
1775S5
Scanner
1775SR5
Scanner
18751
Diagnosing Faults with
Module Status Indicators