Rockwell-automation 1775-MX_S4A,D17756.3.1 User Manual PLC-3 BACKUP CO Manual de usuario descargar pdf (Pagina 8)

Chapter

1-1

Choosing a Backup Configuration

The information in this chapter can help you:

understand backup concepts

evaluate different backup configurations

choose a switchover method

A backup system consists of two processors configured in such a way that

the backup processor will take control of outputs if the primary processor

faults. Figure 1.1 shows the basic concept of a backup system.

Figure 1.1

Basic

Backup System

PRIMARY

PROCESSOR

BACKUP

PROCESSOR

TO/FROM I/O

I/O I/O

BACKUP

COMMUNICATION

10971I

A second processor, which is identical to the first, is connected to the main

processor. During normal operation, the backup processor operates in a

listen-only mode. If the primary processor encounters a major fault, the

backup processor takes control of the outputs. This transfer of control also

can occur due to a loss of power to the primary processor or a broken

cable.

Chapter Objectives

Backup Concepts

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Rockwell-automation 1775-MX_S4A,D17756.3.1 User Manual PLC-3 BACKUP CO Manual de usuario Pagina 8