Switchover Methods with Application Mismatch
Original instructions
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Switchover can be performed using one of two methods:
NOTE:
If bits %SW60.1 and %SW60.2 are set to 0 simultaneously, a Switchover occurs:
  • Primary CPU controller goes RUN Offline, and
  • Standby CPU controller now operates as RUN Primary CPU.
Switchover Using Front Panel Keypad
To force a Switchover using the front panel keypad, do the following:
Step
Action
1
Access the front panel keypad of the Primary CPU controller.
2
Go to PLC Operation menu.
3
Go to Hot Standby submenu.
4
Go to Hot Standby mode
5
Modify Run to Offline.
Note: Verify that Standby CPU switched to Primary CPU.
6
Modify Offline to run.
Note: Verify that the LCD displays Run Standby.
Command Register Switchover
To perform the Switchover using Command Register system bit %SW60.1 or %SW60.2:
Switchover Using Command Register System Bit %SW60.1 or %SW60.2
To force a Switchover by setting the bits in the Command Register, do the following:
Step
Action
1
Open file 1 in Control Expert.
2
Connect Control Expert to the Primary CPU.
3
Verify the A/B controller order of the Primary CPU.
4
Set correct bit in %SW60:
  • If the connected CPU is A, set Command Register bit %SW60.1 to 0.
  • If the connected CPU is B, set Command Register bit %SW60.2 to 0.
    NOTE: Ensure that the Standby CPU switched to Primary CPU.
5
Open file 2.
6
Connect Control Expert to the new Primary CPU controller.
7
Set Command Register system bit used in Step 4 to 1.
NOTE: Verify that the Standby PLC is now online.
8
Verify that both Primary and Standby CPUs are in Run Primary CPU and Run Standby CPU modes.