GFK-1527A 3-1
Configuration Requirements
This chapter defines the special configuration requirements of an Enhanced Hot Standby CPU
Redundancy system.

Programmer Connection for Configuration

In a Hot Standby CPU Redundancy system, one CPU is configured as the Primary CPU and the
other as the Secondary CPU. The Prim ary Unit and the Secondary Unit must be con figured
separately. The programmin g devi ce m ust be connected directly to eit h er the Primary or the
Secondary Unit to configure that unit. For a new system, STORE configuration first, then logic.
C
P
U
C
P
U
B
T
M
R
C
M
G
B
C
30
Secondary Unit Primary Unit
31
P
SP
S
B
T
M
R
C
M
G
B
C
Genius Bus
To Pro
g
rammer

One Application Program in Both PLCs

Although it is not necessary to use the same application program logic for both PLCs, it is difficult
to maintain a system that uses t wo di ffer ent programs. If the programs ar e n ot th e same, logic
changes made in one system must be hand-keyed into the program folder for the other PLC. Other
than visual inspection, there is no way to tell if changes made in one system have been
appropriately made in the oth er.

Program Folders in Control Programming Software

With the Control programming software, a single folder may be used if the logic is identical for
both CPUs.
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Chapter