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S5-95F
14.4
Programmer Control Functions
For safety reasons, the programmer control functions are restricted in failsafe systems. In such
systems, only read-only programmer functions may be invoked. The only exception is the parameter
control DB, which can be both read out and modified via the programmer in failsafe STOP mode.
Parameter Control DB
In failsafe STOP mode, you may modify the parameter control DB via the programmer. The main
advantage of the parameter control DB is that it allows you to wait to initialize certain parameters
until the system is actually operating. It goes without saying that these parameters must be
subjected to range checks in a so-called filter routine, which must be part of your user program. This
filter routine must be approved just like any other user program block by the person conducting the
acceptance test.
You must enter the number of the parameter control DB in DB1 with the COM 95F software.
STOP per Programmer Request
Safety Note
There is no interlock on the switchover from STOP to RUN per programmer request,
and it requires only a simple keystroke on the programmer keyboard. For this reason,
you must not regard a programmer-induced STOP as safety condition. You should
therefore always switch the S5-95F off for maintenance via its own switch.
Lengthening the Cycle Time via Programmer Functions
Note
The execution of programmer functions increases the PLC cycle time. This applies
particularly to the STATUS function, as the S5-95F processes the blocks in a special
mode when this function is invoked. This, in turn, considerably increases the blocks'
runtime, which is operation-dependent.
EWA 4NEB 812 6210-02
Testing the User Program and Storing It on the Memory Submodule
14-13
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