GE Industrial Solutions Entellisys 5.0 Integrator's Guide - Manual (Page 16)

Control Features 16
NOTE: All protection relays will continue operating on both CPUs in a fully redundant fashion
independent of the External Control feature.
1.4.2 Application
The 3rd party supervisory control application must be programmed to monitor the health of the
communication and determine the active CPU.
1. Verify that “External Control Transfer is enabled: Read the CPU External Control Transfer
Enabled register (95A4). Ensure that this feature is enabled before proceeding.
2. Determine Communication Status: Continuously read the Main Task Heart Beat register
(02FF) from both CPUA and CPUB. If the “Main Task Heart Beat” is incrementing, the CPU is
online and running. If the “Main Task Heart Beat” is not incrementing, then the Entellisys
firmware is not running.
3. Determine the Active CPU: If the CPU is online and running, read the FlexLogic Active
register (9588) from both CPUs. The active CPU will return a “1.”
4. Determine the “External Control Transfer Mode”: Read the Flexlogic Redundancy Mode
register (959D) to determine the mode.
5. Command Case: There are four conditions that require the client to force a CPU to become
the active CPU.
a. If only CPU A is online and its FlexLogic is not active, then the client will command CPU A
to take control. After the system returns to normal, the client must command CPU A to
Return to Auto Control Transfer.
b. If only CPU B is online and its FlexLogic is not active, then the client will command CPU B
to take control. After the system returns normal, the client must command CPU B to
Return to Auto Control Transfer.
c. If both CPU A and CPU B are online and neither are active, then the client will command
either CPU A or CPU B to take control. This condition is only caused by a configuration
error and must be corrected by a GE field service engineer. After the system has been
restored to normal, the client must command the active CPU to Return to Auto Control
Transfer.
d. If both CPU A and CPU B are on-line AND if the Flexlogic Redundancy Mode register on
either CPU A or CPU B is greater than 0 then return to Auto by sending each CPU a Return
to Auto Control Transfer command.
1.4.3 FlexLogic
New protection elements have been added to FlexLogic to report the status of the Control
Transfer function.
• CPU Control Active CPU A: High when CPU A is the active CPU either by Entellisys or an
external device.
• CPU Control Active CPU B: High when CPU B is the active CPU either by Entellisys or an
external device.