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S5-115F Manual
10
Rules Governing the Use of the S5-115F in
Safety-Related Applications
In Chapter 9 you will have learnt the principles of the safety-related structure of the S5-115F. In
Chapter 10 you will find all those rules that must be observed when using that part of the S5-115F
requiring official approval.
These rules must be observed in order to avoid
•
Danger to life and limb and
•
Controller malfunctions.
10.1 The User Memory
•
Both subunits, A and B, require the same memory configuration.
If you use memory submodules, they must both have the same order number.
•
The S5-115F automatically operates in safety mode when EPROM or EEPROM submodules are
plugged in. You can, however, only use EEPROM submodules with the express consent of the
inspector at the individual acceptance test. If you operate the S5-115F without memory
submodules or with a RAM submodule, it automatically switches to test mode.
•
The backup batteries are essential. Error information can be lost without battery backup for
the RAM.
Replace the backup batteries every year.
•
Nonsafety-related programs must be reaction-free:
- Operations which change the memory must have no effect on safety-related data.
- The degree to which the system is reaction-free can be demonstrated using data flowcharts
or cross-reference lists.
10.2
The Logical Program Counter
Using the logical program counter (LPLZ), the operating system can check that the same number
of program sections have been processed in both subunits.
The following sequence of operations increments the LPLZ
L
FW 0
L
KF
+1
+
F
T
FW 0
EWA 4NEB 811 6148-02
Rules Governing the Use of the S5-115F
10-1
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