Emerson Redundancy SLS 1508 Logic Solver modules

Redundancy

The redundant SLS 1508 Logic Solver modules are connectedto the field at the redundant

terminal block. No control strategy configuration is required to take advantage

of SLS 1508 Logic Solver redundancy, as the system’s auto-sense capability

automatically recognizes the redundant pair of Logic Solvers.

An integrity error alarm in a redundant SLS 1508 Logic Solver pair will notify

the operator of a failure. Both SLS 1508 Logic Solvers in a redundant pair

are monitored for integrity alarms at all times.

Events that can cause integrity alarms include:

• Hardware failure within a SLS 1508 Logic Solver

• Communications failure between a SLS 1508 Logic Solver and the SISNet

• Communications failure between a redundant pair of SLS 1508 Logic Solvers

• Communications failure between a SLS 1508 Logic Solver and an DeltaV Controller

• Removal of a SLS 1508 Logic Solver from the carrier

The health and status of both SLS 1508 Logic Solvers and their channels are

available in the diagnostics explorer.

When one of a redundant pair of SLS 1508 Logic Solversis removed online there

is no disturbance to the process.

When the missing SLS 1508 Logic Solver is replaced with another SLS 1508 Logic Solver,

the new SLS 1508 Logic Solver completes its power-up self-tests before the

active Logic Solver cross-loads the current database.

In safe areas, failed SLS 1508 Logic Solvers can be replaced under power.

In hazardous areas,appropriate installation procedures must be followed.

Automatic proof testing can be selected on a redundant pairof SLS 1508 Logic Solvers.

The desired proof-test interval is set in the configuration and the SLS 1508 Logic Solvers perform

the proof test automatically. A warning is given to the operator before

the automatic proof test is started.