Emerson DM6352 Analog input Thermocouple Type K High

While the SLS 1508 Logic Solver is rated suitable for use in SIL 3 applications

in simplex mode, it is installed in redundant pairs for increased process availability.

Redundant SLS 1508 Logic Solvers run in parallel at all times.Both read the inputs

from the I/O terminals, both execute the logic and both drive the outputs at the I/O terminals.

There is no concept of primary and backup or master and slave,which is unlike any other SIS.

The only difference between the two is that one communicates with both the engineering

and operator workstations and the dedicated safety network (SISNet);

this is the one with the Active light on the bezel.The other (Standby) is

communicating only on the SISNet.In the event that a failure is detected in

one of the SLS 1508 Logic Solvers, it automatically goes to a failed state. 

In this condition, all its output channels are de-energized;

this has no impact on the other SLS 1508 Logic Solver or the physical

outputs because the other SLS 1508 Logic Solver continuesto read inputs

execute logic and drive outputs. The transition from redundant to simplex

mode is therefore completely bumpless.

Control Network: The DeltaV Control Network providescommunication between

the nodes in the DeltaV network.Refer to the Installing Your DeltaV Digital

Automation Systemmanual for complete information on the Control Network.

Local Bus: The Local Bus provides communication between DeltaV controllers

and SLS 1508 Logic Solvers and between DeltaV controllers and SISnet Repeaters.

Local Peer Bus (SISNet): SLS 1508 Logic Solvers communicatewith other SLS 1508

Logic Solvers and with local SISNet Repeaters through the carriers over

a 2 channel local peer bus.

The same message is broadcasted over both channels. The localpeer bus must

be terminated at both ends. The local peer bus is terminated at the left

end through the 2-wide power/controller carrier and at the right end

through a terminated 1-wide carrier.