Operating And Changing Safety-Related Parameters On A Pcs 7 Os; Safety Data Write (Sdw) - Siemens SIMATIC PCS 7 Operating Manual

Configuring the safety program

7.10 Operating and changing safety-related parameters on a PCS 7 OS

7.10 Operating and changing safety-related parameters on a PCS 7 OS
Changes to fail-safe parameters on a PCS 7 OS can be made using the following options:
● Safety Data Write (SDW)
● Safety Matrix
● F_QUITES for fail-safe acknowledgment
● Maintenance Override Switch (MOS)
7.10.1

Safety Data Write (SDW)

Introduction
The "Safety Data Write" function enables safety-related changes to be made to F-
parameters in the safety program of an F-CPU via an OS.
A special safety protocol is used to make changes to F-parameters in safety mode. This
meets Safety Integrity Level requirements up to SIL3 in accordance with IEC 61508.
Modified values of F-parameters can also be retained following a restart (warm restart) of
F/FH systems.
S7 F-systems offers the following for SDW:
● Two F-blocks, which you integrate into the CFC charts in your safety program
– F_CHG_R: SDW for F_REAL data type F-parameters
– F_CHG_BO: SDW for F_BOOL data type F-parameters
● Associated faceplates, which you integrate into your OS. Two identification values
(Safe_ID1 and Safe_ID2) are used to uniquely assign each faceplate to a block in an AS.
Transaction for SDW
You can use SDW to modify an F-parameter in the safety program of an F-CPU if you
execute a specific sequence of operations on the OS within a specified period of time. The
entire change operation is known as a "transaction".
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Compendium Part B - Process Safety (V8.2)
Operating Manual, 07/2016, A5E35031794-AB