Month: November 2025

LSN Hardware Includes:

• NextGen DeltaV SIS Smart Switches

• Ethernet Isolation Ports on the SZ Controller

•  SNPs on the CSLS carrier

•  LSNB to communicate with other LSNs through a GSN.

A redundant CSLS communicates over the LSN with up to

15 other CSLSs, 1 SZ controller, and 1 LSNB allowing great

flexibility and ease of system expansion.

Only DeltaV SIS Smart Switches are supported on the LSN.

The LSN is certified according to the concept of black channel

per IEC61508-2. Therefore, the LSN hardware components

are considered as an interference free hardware component of the SIS.

The SZ controllers and CSLSs can be physically connected

as a star topology (the LSN does not support network

ring topologies).

Starting with DeltaV SIS v13. the LSN Bridge (LSNB) allows

communication across multiple LSNs. The LSNB connect

to the LSN following a star topology.

For Use in Safety Integrity Level

(SIL) 3 Applications

The LSN is certified for use in SIL 3 applications.

Wiring

The LSN requires the use of Category 5e screened (ScTP)

cable for the 100/1000 BaseT/TX safety network.

The maximum twisted-pair cable length for the LSN for any

device is 100 meters (328 feet).

The CSLS, LSNB, and SZ controller carriers contain Ethernet

ports to provide the redundant communication for the LSN.

Fiberoptic Wiring

Safety network ports (SNP) on the CSLS are available for

copper only. DeltaV SIS Smart Switches can be connected

using fiberoptic cables.

Because fiberoptic cables do not conduct electricity,

they should be used in connections between buildings

or in plant areas where electromagnetic interference is present.

Fiberoptic cabling must be used where cable runs are longer

than 100 meters (328 ft.).

LSN Description and Specification

The SZ controllers and CSLSs can be physically connected

as a star topology (the LSN does not support network

ring topologies).

Starting with DeltaV SIS v13. the LSN Bridge (LSNB) allows

communication across multiple LSNs. The LSNB connect

to the LSN following a star topology.

Refer to the latest DeltaV SIS Installation and Planning Guide

for details of network layouts and network cable shielding

requirements and power and grounding requirements for

the overall DeltaV SIS system.

A redundant CSLS communicates over the LSN with up to

15 other CSLSs, 1 SZ controller, and 1 LSNB allowing great

flexibility and ease of system expansion.

Only DeltaV SIS Smart Switches are supported on the LSN.

The LSN is certified according to the concept of black channel

per IEC61508-2. Therefore, the LSN hardware components

are considered as an interference free hardware component of the SIS.

Scalable in small increments. You can expand the system

readily and economically by adding hardware incrementally

to your system. Just plug another CSLS into the LSN and it is

recognized by the system. Online addition of new CSLSs will

not interrupt your process.

Fully redundant communications. The safety networks are

fully redundant communication networks. The carriers for all

nodes have redundant safety network ports for communication

with primary and secondary network connections.

Port mirroring functionality. Port Mirroring can be

configured on the NextGen Safety Network Switches

either with an “administrator” role or a “engineer” role.

These switches have the capability to mirror the traffic of

several source ports, in a read only manner, to a destination port (probe port).

Benefits

Dedicated to safety. Some systems from other

vendors use the same networks for both control and

safety. The DeltaV SIS LSN and GSN are dedicated to safety,

carrying only safety-rated signals and isolated from the

control network. They are therefore immune to any failure

of the control network.

Fifty millisecond update time. All the data broadcast on the

LSN is available to every CSLS on the same LSN every

50 milliseconds. Combined with the speed of the CSLS,

the 50 millisecond update time guarantees input-to-output

time of less than 300 milliseconds anywhere on the LSN

when the CSLS is configured for 50-millisecond scan rate.

Plug-and-play components. As a dedicated safety network

with predictable communications traffic, Emerson has done all

of the system testing so you only have to plug the components

together to create the safety networks.

Standards compliance. Network components are compliant

with standards such as IEEE, CE, and CSA.

• Dedicated to safety – no possibility

of common-cause control and safety

communication failures

• Required update time supported on

the DeltaV SIS™ local safety network

• Scalable and cost-effective

• Fully redundant networks

Introduction

The local safety network (LSN) is the communication backbone

of the DeltaV SIS™ process safety system. The LSN is a standard

Ethernet network dedicated to the DeltaV SIS system that

enables communication between CHARMs smart logic solvers

(CSLS) and a single SZ controller. The CSLSs communicate

secure parameters and input data to other CSLSs over the LSN.

SZ controllers connect to both the area control network and

the LSN to isolate the CSLSs from the process control system.

Starting with v13. the global safety network (GSN) enables

safety-rated communication among LSNs while allowing

functional segregation on different LSNs. A typical example is

separation of fire and gas (F&G) and emergency shutdown

(ESD) applications over separate LSNs while allowing safe and

secure communication across both applications. Starting with

v14.LTS, the GSN can be logically separated in domains which

are a group of LSNs.