Schneider Electric 840 USE 106 0 Using CHS Instruction Block, Hot Standby Command Register Hazard

Using a Quantum 984 HSBY System

Using CHS Instruction Block

CHS Instruction The command register is defined in the top node of the CHS instruction block. The

Blockbits in this register are used to configure and control various parameters of the Hot Standby system.

The command register must be a 4x register in the portion of the state RAM transfer area that is transferred from the Primary to the Standby controller on every scan. It also must be outside of the nontransfer area.

Disables keyswitch override = 0

Enables keyswitch override = 1

Sets Controller A to OFFLINE mode = 0

Sets Controller A to RUN mode = 1

Sets Controller B to OFFLINE mode = 0

Sets Controller B to RUN mode=1

Forces standby offline if there is a logic mismatch = 0

Does not force standby offline if there is a logic mismatch = 1

Allows exec upgrade only after application stops = 0

Allows exec upgrade without stopping application = 1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

0 = Swaps Modbus port 1 address during switchover

1= Does not swap Modbus port 1 address during switchover

0 = Swaps Modbus port 2 address during switchover

1 = Does not swap Modbus port 2 address during switchover

0 = Swaps Modbus port 3 address during switchover

1 = Does not swap Modbus port 3 address during switchover

CAUTION

Hot Standby Command Register Hazard

Take precautions to be sure the register you select as the Hot Standby command register is reserved for this purpose and not used for other purposes in ladder logic.

Failure to follow this precaution can result in injury or equipment damage.

The values set for the bits in this register determine the system parameters at startup. The register can be accessed while the system is running using a reference data editor (RDE) or a Zoom screen on the CHS instruction in ladder logic.

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