GE Industrial Solutions Entellisys 5.0 Integrator's Guide - Manual (Page 14)

Control Features 14
1.4 CPU External Control Transfer
Entellisys is designed with redundant CPUs - both CPUs run protection functions simultaneously,
however, the CPU control redundancy scheme utilizes primary/hot backup redundancy
approach. By default, CPU A is the primary and CPU B is the backup.
The primary runs as the active CPU and the backup runs as the inactive CPU. The active CPU has
contact outputs and circuit breaker control commands actuated, and the inactive CPU has
contact outputs and circuit breaker control commands blocked. Only one CPU can be active at
any given time. Modbus register
FlexLogic Active , address 9588, holds 1 when the CPU is active
and holds 0 when the CPU is inactive.
Internally Entellisys, depending on the system state, will determine which CPU should be running
as the active CPU and, if necessary, automatically hand off control to optimize the performance
of the gear.
In an application with a supervisory control structure, the 3rd party Modbus TCP supervisory
client will communicate to both CPUs but in the event that it cannot communicate to one of the
CPUs, it will need to force the remaining CPU to operate as and continue to operate as the active
CPU.
Figure 1-4 Typical 3rd party redundant network configuraton
C
Contact GE for additional information on a specific redundant network application.
To effectively employ the CPU External Control Transfer into a supervisory control schema, the
supervisory controller must continuously monitor the state of the communication and issue
commands based on the guide lines in
section 1.4.2 on page 16 .
CAUTION: Redundant I/O must be used if contact inputs or outputs are being used in a
FlexLogic control application.
Events:
• CPU External Control Transfer Command Received: CPU received a “CPU External
Control Transfer” command.
• CPU Control Transfer Return to Auto Command Rcvd: “CPU Return To Auto Control
Transfer” command