Siemens Welding System ST PCS 7 Manual De Usuario

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Automation systems
 
Safety-related automation systems
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Siemens ST PCS 7 · Update November 2008
10
Function
Safety functions
The safety functions of an application are implemented by the 
safety-related program executed in the CPU of the F/FH systems 
together with the safety-related F-modules of the ET 200 distrib-
uted I/O systems or directly by failsafe transmitters connected 
via the fieldbus. 
The PROFIsafe profile is used for the safe PROFIBUS DP com-
munication between CPU and process I/O. PROFIsafe expands 
the message frames by additional information with which the 
PROFIsafe communications partners can recognize and com-
pensate transmission errors such as delays, incorrect se-
quences, repetitions, losses, faulty addressing or data falsifica-
tion.
Standard modules can be used in F/FH systems in addition to 
safety-related F-modules - mixed in a remote I/O station or in 
separate stations, in a common PROFIBUS segment or in sepa-
rate PROFIBUS segments. Basic process control (BPCS) appli-
cations and safety applications can be automated in such mixed 
configurations with one and the same system and configured 
with uniform standard tools. 
One CPU processes BPCS and safety functions in parallel. 
Mutual interference during processing is prevented by ensuring 
that the BPCS programs and the safety-related programs are 
kept strictly separate and that the data exchange is by means of 
special conversion function blocks. The safety functions are pro-
cessed twice in different sections of a CPU by means of redun-
dant, diverse instruction processing. Potential errors are de-
tected by the system during the subsequent comparison of 
results.
The S7 F Systems engineering tool as a component of the 
SIMATIC Manager allows parameterization of the F/FH systems 
and the safety-related F-modules from the ET 200 series. It sup-
ports configuration by means of functions for:
• Comparison of safety-related F-programs
• Recognition of changes in the F-program using the checksum
• Separation of safety-related and standard functions.
Access to the F-functions can be password-protected.
The F-block library integrated in S7 F Systems contains pre-
defined function blocks for generation of safety-related applica-
tions with the CFC or the SIMATIC Safety Matrix based on it. The 
certified F-blocks are extremely robust and intercept program-
ming errors such as division by zero or out-of-range values. They 
avoid the need for diverse programming tasks for detecting and 
reacting to errors.
Options
Ordering information
An AS 412H, AS 414H or AS 417H system is required as the 
hardware for a safety-related automation system.
The following H systems can be used depending on the type 
and structure of the safety-related automation system:
• For single-channel AS 412F, AS 414F or AS 417F safety-re-
lated systems: one each of AS 412-3-1H, AS 414-4-1H or 
AS 417-4-1H
• For fault-tolerant and safety-related AS 412FH, AS 414FH or 
AS 417FH systems: 
- With both subsystems in one rack: one each of AS 412-3-2H, 
AS 414-4-2H or AS 417-4-2H
- With the two subsystems in different racks: two each of 
AS 412-3-1H, AS 414-4-1H or AS 417-4-1H
You require the following components in addition:
• S7 F Systems
F programming tool with F block library for programming 
safety-related user programs on the engineering system (see 
Chapter "Engineering system")
• F Runtime license
For processing safety-related user programs, for one 
AS 412F/FH, AS 414F/FH or AS 417F/FH system
• Option: SIMATIC Safety Matrix 
The convenient safety lifecycle tool for configuration of opera-
tion and servicing (see Chapter "Engineering system")
© Siemens AG 2008