Standardizing Blocks; Standardizing Sensor Evaluation - Siemens SIMATIC S7-1200 Safety Programming Manualline

3 Methods for Safety Programming
3.5

Standardizing blocks

Aside from the actual evaluation of a sensor / control of an actuator, the same
conditioning of input and output parameters is often necessary (e.g., edge
evaluation, time functions, acknowledgment, etc.).
To this end, it is useful to create and reuse modular blocks.
Siemens Industry Online Support provides block libraries you can use in your
project, for example "LDrvSafe":
https://support.industry.siemens.com/cs/ww/en/view/109485794
Recommendation
Create modular blocks you can reuse:

Blocks for typical fail-safe sensors

Blocks for typical fail-safe actuators

Blocks for frequently used functions (e.g., reintegration, operating mode)
Advantages

Reused blocks have to be accepted only once

Quick programming of additional functions and projects

Versioning possible with the TIA Portal library concept

Standardization of formal parameters across projects and programmers,
resulting in easy readability and testability
Note The following block programming shows examples. The actual function depends
on the application's risk assessment or the project requirements.
3.5.1

Standardizing sensor evaluation

Recommendation
Create a separate function block for each sensor type (e.g., emergency stop
command device, safety door, light curtain, etc.) that combines the evaluation of
the sensor and the necessary auxiliary functions. Use this sensor block for other
sensors of the same type.
Create F-data types for complex sensors.
Auxiliary functions for a safe sensor include, for example:

Reset

Restart interlock

Time functions

Edge evaluation

Startup test

Provision of diagnostic information
Safety Programming Guideline
Entry ID: 109750255, V1.0, 10/2017
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