Rockwell-automation 1775-MX_S4A,D17756.3.1 User Manual PLC-3 BACKUP CO Manual de usuario descargar pdf (Pagina 105)

Chapter

6-1

Diagnosing Faults

This chapter describes how to diagnose faults in a PLC-3 backup system

using:

status indicators on the front panels of processors and on the front

panels of modules in the processors

system status words.

Also, it describes a simple diagnostic technique that can help you identify

the program section and rung number of faults when they occur.

Before discussing fault diagnosis, however, you should review what

happens when a processor encounters a major fault.

If the primary processor determines that a major fault exists while it is in

run mode, the primary processor will:

display the message DEACTIVE on the front panel of the primary

processor if a 1775-S4A or -SR is scanner number one; or display the

major fault on the front panel of the primary processor if a 1775-S5 or

-SR5 is scanner number one.

switch to program load mode

pass control to the backup processor

cause a fault message to appear on the screen of a programming

terminal, if one is being used.

Chapter Objectives

How the Backup System

Behaves When a

Major Fault Occurs

1 2 ... 100 101 102 103 104 105 106 107 108 109 110 ... 118 119

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Rockwell-automation 1775-MX_S4A,D17756.3.1 User Manual PLC-3 BACKUP CO Manual de usuario Pagina 105