Page 314 - Programmable Logic Controllers, Fifth Edition - Mobile version

Output device troubleshooting guide
Output device Output module Monitor display
condition status indicator status indicator Fault(s)
True
ON None - correct indication
Energized — ON

False
OFF None - correct indication
De-energized — OFF

True Output instruction and status indicator
ON agree but the field device does not.
De-energized — OFF Open field device or wiring.
Module circuit or fuse.
True Field device status and status indicator
OFF agree but the output condition does not.
De-energized — OFF Module circuit or fuse.

Output module
status indicator Output module
ON L1

Open in wiring
VAC
OUT 0
OUT 1
OUT 2
Open in field device
OUT 3
OUT 4
OUT 5
OUT 6
OUT 7
AC COM L2

Figure 13-23 Output troubleshooting guide.
Source: Photo courtesy Guardian Electric, www.guardian-electric.com.

– Errors
Program Files
–
File 2
–
Ring 1 Ins 3: ERROR: Unconfigured I/O (I:20/6)
Verify Results
Figure 13-24 Sample of verifying program errors.

Certain diagnostic instructions may be included as part
of a PLC’s instruction set for troubleshooting purposes.
The temporary end (TND) instruction, shown in Fig-
ure 13-26, is used when you want to change the amount of Figure 13-25 Indication of enabled forces.
logic scanned to progressively debug your program. The Source: Courtesy of TheLearningPit.

PLC Installation Practices, Editing, and Troubleshooting Chapter 13 295

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