Response Electronics CL6011B Dokumentacja Pobierz pdf (Strona 73)

3Ć53 Theory of Operation: Redundancy

Original Ć June 1990 CE4.2:CL6211

3.6 Redundancy

Interactive and Computing controllers can be applied in a redundant

physical configuration. The user's application configuration can be

directly applied to a redundant controller set, as long as the redundant

controller loading is not exceeded. That is, there is nothing specific that

the user must configure in order to apply his control strategy to a

redundant controller application.

PROVOX Redundancy is designed to maintain system availability (both

control and operator interface) under any single point failure condition.

Any single failure in the redundant system will cause the PROVOX

system to automatically switch in a redundant unit, if necessary, to

recover from the fault. System availability under multiple failure

conditions is not specifically guaranteed. However, no design constraints

have been applied to preclude the system functioning at an optimum

level under multiple failure conditions.

3.6.1 Redundancy Architecture and Definition of Terms

The physical connection and installation of the redundant controllers

determines the PRIMARY and SECONDARY controller assignments. The

PRIMARY controller refers to the controller normally intended to have

control of the output channels. The SECONDARY controller is normally

intended to be following the action of the PRIMARY controller, awaiting to

resume the control functions on demand.

The terms ACTIVE and STANDBY refer to which controller is currently

operating the output channels. An ACTIVE controller has control of the

output channels, and is performing its normal control algorithm. A

STANDBY controller does not have control of the output channels, and is

being forced to track the current operating conditions of the ACTIVE

controller.

Although it makes no difference to the operation of a PROVOX control

system, the PRIMARY controller is normally intended to be the ACTIVE

unit (controlling the output channels). The SECONDARY controller is

normally intended to be the STANDBY unit (tracking the ACTIVE unit,

prepared to resume control operations).

For clarity, SWITCHOVER refers to the transition from the PRIMARY

controller in the ACTIVE state, to the SECONDARY controller assuming

the ACTIVE state. Similarly, SWITCHBACK refers to the transition from

the SECONDARY controller in the ACTIVE state, to the PRIMARY

controller assuming the ACTIVE state.

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Response Electronics CL6011B Dokumentacja Strona 73