GE Industrial Solutions Entellisys 5.0 Integrator's Guide - Manual (Page 15)

CPU External Control Transfer 15
• CPUx Assumes Control Logic By External Command: CPU has executed the “CPU
External Control Transfer” command and assumed active control.
• CPUx Relinquishes Control Logic By External Cmd: CPU relinquishes control after the
client issues “CPU Return To Auto Control Transfer” command or other CPU requests this
CPU to relinquish control.
Function Enable
The CPU External Control Transfer function can only be enabled by the factory. When disabled,
the associated modbus command registers and FlexLogic elements remain low and ignore all
write operations.
1.4.1 Operation
The only interface the user has for this function is through Modbus TCP.
Command Registers
• CPU External Control Transfer - Writing a “1” to this register will force the CPU to
become the active CPU and begin executing FlexLogic. This process will take up to 150ms
(180ms for 50Hz system).
• CPU Return To Auto Control Transfer - Writing a “1” to this register will return the CPU
back to normal operation. Return to automatic control transfer process will take up to
250ms (300ms for 50Hz system).
Status Registers
• CPU External Control Transfer Mode Enable: Indicates that the function is enabled and
ready.
• Main Task Heart Beat: This is a new register to indicate that the main task is running.
Every time the main task is executed (every half cycle), this register value is incremented
by one, from 1 to 65535. When the register overflows, it will reset to 1. If the main task is
not running, this register is not incremented but a client can still read the register value. If
the main task was never started, this register will remain zero.
• Active FlexLogic Control: Indicates the active CPU.
• FlexLogic Redundancy Mode: Indicates the CPU control transfer mode. There are two
modes: CPU Auto Control Transfer Mode (“0”) and CPU External Control Transfer Mode
(“1”).
Details:
• When a CPU receives an External Control Transfer command, it will request the other CPU
to relinquish control. Once the other CPU relinquishes control, the commanded CPU will
assume control and set the Active FlexLogic Control state high.
• Any External Control Transfer command requires a complementary Return to Auto
Command to resume normal operation.
• If both CPUs have received an External Control Transfer command, normal operation will
only resume after both CPUs have received the Return to Auto command.