#134 - TIA Portal Safety Programming Blocks tips and examples

It is recommended that the Safety Program follows a set of guidelines in order to ensure it properly works. Here below some of the points to remind when programming a Safety PLC:

Tips:

> Isolate the Access to the Safety Program via DBs (optimized block access), such as DataFromSafety and DataToSafety.

Source [1]

Note that only a Standard FB can write/read to/from these DBs. This means that HMI direct access is not recommended but also any other device in the project (PUT/GET partner, external devices, etc).

> For a Safety Input signal only use Safety signals (yellow marked)

> Use only one instruction per network

> "In case of passivation (card fault or comms fault), the F-I/Os will switched into in the fail-safe state. After fault correction, the F-I/Os can be reintegrated." [4] Note: Depending on the F-I/O it is possible to set the reintegration to be done automatically. Also it is possible to reset ACK_BLOB during the first scan of the PLC.

Example:

References:

[1] Siemens: What should you do if the F-CPU goes into STOP mode and the message "Data corruption in the safety program ..." appears in the diagnostics buffer?

[2] Siemens: How can an overflow of arithmetic operations in the fail-safe program be intercepted?

[3] Siemens: SIMATIC Industrial Software SIMATIC Safety - Configuring and Programming

[4] Siemens: Safety: Passivation and Reintegration of F-I/O

[5] Siemens: Protective Door with Spring-loaded Interlocking

[6] Siemens: Safety Programming Guideline for SIMATIC