Programming / parameter assignment
Instruction Manual PROTECT-PSC
V 2.6R01 / 04.19
6-31
6.10
Programming
The programs are created exclusively graphically in the form of a ladder diagram.
Since the PROTECT-PSCsw programming software is primarily intended for the
creation of user programs for the safety-orientated use of the PROTECT-PSC only
those instructions and functions of IEC 61131 are available which can be checked
in terms of safety using simple means. The statement list programming language
used to check the user program contains a few necessary additions which are not
a part of the IEC 61131.
It is assumed that the programmer has already gathered appropriate experience
with the programming languages of ladder diagram (LD) and statement list (STL). If
the requisite basic know-how does not exist, intensive familiarisation with the
theme is necessary before creating the program. Even if the PROTECT-PSC con-
troller satisfies the highest safety requirements in machine / man protection, this is
no protection against faulty (from a safety point of view) user programs. The inte-
grated program check can merely test the logical structure of the user program.
6.10.1
Basic program flow
Before executing the user program, the states of the inputs are queried and stored.
The inputs are not queried during execution of the user program.
The user program is subdivided into several numbered contact blocks. Each block
can consist of several lines. A line constitutes the equivalent of an electrical con-
nection from the input (left) to the output (right). An input is always a contact (read-
ing of an address) and the output is always a coil/function (writing of an address).
A block consists of at least one line with at least one coil. The starting point of a
block is always 1/high. A block can consist of a maximum of 22 lines and a total of
256 symbols (contact, coil, function). The number of blocks is only restricted by the
maximum admissible program size or run time.
Please bear in mind during program creation that the user program is always
worked through from top to bottom. The unfavourable placement of the individual
program blocks has a very negative effect on the reaction time. This applies in par-
ticular to the use of flags. Therefore always switch safety enables (coils) directly
and ensure that the safety enables are shut down after a change in level at the in-
put in the same program run.
Summary of Contents for PROTECT-PSC
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