S5-95F
Rules for Failsafe Operation of an S5-95F
Decide on Which Timers and Counters are Relevant to Failsafety
The inspector decides which timers and counters are relevant to failsafety. This decision includes
values for system parameters which must be initialized with COM 95F, such as
•
Maximum discrepancy times
•
The OB13 interval
Stipulate system-specific values, such as
•
The maximum total response time (response time of the PLC+the response time of sensors and
actuators)
•
The maximum permissible number of firing attempts (in the case of heating systems)
Hardware Requirements
All modules and subracks which can be used in conjunction with an S5-95F are prototype-tested by
the Bavarian Technical Inspectorate, and require no further hardware tests. The modules are
subdivided into failsafe modules and non-interacting modules.
Care must be taken that all electrical resources have the necessary properties. Among other things,
the inspector tests the following:
•
Whether the electrical resources are failsafe or non-interacting
•
Whether the technical specifications meet with the required ambient conditions, e.g. EMC,
temperature and humidity rating
Communication with Other Components
If you plan communications to other components, answer the following questions:
•
Who are the partners in the communications link?
•
Should data transfer be unidirectional or bidirectional?
•
Are safety-related data to be transferred?
•
Could data transfer result in falsification of safety-related data in the S5-95F?
Data interchanges with partners in a communication link must in no way impair the failsafety of
functions or subprocesses. For this reason, be sure to check all interfaces in a
•
Point-to-point connection (e.g. link via a CP 521)
•
Bus system (e.g. SINEC L1)
If you want failsafe postprocessing of failsafe data, you always require a failsafe communications
link, such as a link via SINEC L1.
The transfer of non-failsafe data requires, at the very least, non-interacting hardware.
Documents for the Pre-Acceptance Inspection
Ask the inspector which documents you are expected to supply at the pre-acceptance inspection.
EWA 4NEB 812 6210-02
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