BBH SCU Series, Installation Manual

Page: 174 / 303

18
Information for design,
programming, validation and test
HB-37500-810-11-16F-EN SCU Installation Manual - Master and Slaves - SARC Page 174 of 303
Status: 09.06.2022
18.3.8. Hardware design and software design
The stipulations of the hardware design and the stipulations of the software design are
implemented in the design of the proper plant.
The stipulations for the components to be used and for their circuitry that are indicated in
the hardware specification must be observed just as the stipulations for the error
exclusions. The compliance with each of the above stipulations must be ensured and
documented by appropriate means.
In the software, also the stipulations of the software specification must be observed and
must be completely implemented.
Furthermore, here the subordinate stipulations for the software concerning safety-relevant
programming must be observed. Stipulations for safety-relevant programming are among
others:
• Clear and modular structure of the program
• Assignment of the functions to the safety functions
• Understandable presentation of the functions by:
o
Unique designations
o
Understandable comments
o
Use of tested functions or tested function block to the greatest possible
extent
• Defensive programming
18.3.8.1. Testing of the hardware design
After planning is completed, it must be checked if the hardware design complies with the
stipulations indicated in the hardware specification.
Furthermore, for every safety function the compliance with the specified safety level must
be checked by means of an appropriate analysis. The analysis procedures are described in
the relevant standards (e. g. EN13849-1).
18.3.8.2. Analysis of the circuit diagram
The complance with the safety-relevant stipulations must be checked by means of the
switch diagram and by means of the piece list. In particular, the following items must be
checked:
• The correct circuitry of the components according to the respective stipulations.
• The two-channel structure, if stipulated.
• The die Rückwirkungsfreiheit von parallelen, redundanten Kanälen.
• The use of the components according to the respective stipulations.
The audit is to be carried out by comprehensible analysis.