Rockwell Automation AADvance Controller Configuration Guide - Manual (Page 235)

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Document: 553633
ICSTT-RM405f-EN-P
Issue 07
10-1
AADvance provides SNCP and supports both variable bindings functionality and IXL
communication over a safety control network. This chapter describes the process for
setting up SNCP networks and variable bindings.
In This Chapter
SNCP Safety Networks ................................................................................... 10-1
SNCP Safety Networks
SNCP (Safety Network Control Protocol) is the Safety Protocol that allows
elements of an AADvance System to exchange data. AADvance SNCP is a SIL 3
certified protocol which provides a safety layer for the Ethernet network making it a
"Black Channel". Data is exchanged by creating a relationship between variables in
different AADvance controllers; this is called "Binding Variables". Once variables are
bound between controllers the SNCP protocol provides a transparent SIL 3 Certified
layer allowing safety related data to be passed between AADvance controllers.
The bindings are based on a producer/consumer model. The controller consuming the
data establishes a binding link with the Controller producing the data, and manages the
entire exchange of data, including scheduling the data exchange, providing the
diagnostics, managing the safety response in the event of faults and managing the
communications redundancy.
SNCP Networks can be configured as Simplex (Fail Safe) or Redundant (Fault tolerant),
the choice of network configuration is dependent on the applications safety and
availability requirements. The data exchange is independent of the physical; network
configuration as the connection between the controllers is treated as a logical
network.
The physical network is considered a "Black Channel" so the design of the Ethernet
network and the equipment used does not impact the SIL rating of the
communications interface, but the design of the network does affect the reliability of
the network and does impact the spurious trip rate. SNCP Network data can be
combined on a common network resulting in safety and non-safety data sharing in a
common physical network; this does not compromise the SIL rating of the network
but again does introduce failure modes and possibly security risks which can increase
the spurious trip rate, careful consideration should be given to the network topology
during the applications specification and design phase.
Chapter 10
SNCP and Variable Bindings