Changing The Safety Program - Siemens SIMATIC S7 F Manual

Operation and Maintenance
6.4

Changing the Safety Program

Rules for Changes to the Safety Program
•
Changes to fail-safe input parameters are only possible in safety mode by
using or downloading changes in the standard user program with the help of
conversion blocks F_BO_FBO, F_R_FR, etc. and a plausibility check
programmed with fail-safe blocks.
The simplest form of plausibility check is when a range is specified with fixed
upper and lower limits. The on-site technical expert must always be consulted
about a plausibility check.
Not all the input parameters can be checked for plausibility in a sufficiently
simple way. You can't change these input parameters during operation.
•
The following changes to the Safety Program can be made during operation
(RUN) only if safety mode is deactivated:
- Changing the CFC charts, compiling and downloading the changes to the
CPU.
- Changing fail-safe constants in CFC test mode.
Changing the Safety Program
After making changes to the Safety Program, proceed as follows:
1. Compile the modified Safety Program.
2. Test the Safety Program.
3. Check whether the signatures of the blocks in the block container and the CFC
charts are the same.
4. Check the safety parameters.
5. Carry out acceptance of the changes.
6. Download the entire program or the changes only to the CPU.
7. Archive the entire modified project. The accepted Safety Program must be
saved.
Batch Programming
Parameters that are not safety-related can be changed in the standard program in
a batch process. Safety-related checks of these parameters (e.g. permissible
range, consistency of parameter sets, etc.) must be carried out in the Safety
Program.
Fail-Safe Systems
A5E00085588-03
6-3