PMA KS 98, Manual

Page: 55 / 246

12.8 STEP (step function for sequencing)
The STEP function realizes the individual steps for sequencing.
The function starts with RESET at step 1 and remains at this step, until the relevant condition input d
1
or the skip input
is set from 0 to 1. This is followed by switch-over to step 2. The procedure for all further steps is identical.
The step number is output as a value at output Step.
Example:
Switch-over from step 3 (
Step
= 3) to step 4 (
Step
= 4) is only after the condition at
d3
was met (
d3
= 1). The condi-
tion at
d4
is checked only when calling up the function for the next time. Thus immediate switch-over is prevented. As
long as d3 = 0, the value of output Step remains 3.
Alternatively, a positive flank at input skip also leads to switch-over to the next step (independent of the status at
input
d1
..
d10
).
a
The function has a ‘memory’. This means: after power-on, it continues operating with the step at power-off,
provided that the RAM data are still unchanged.
When several switch-over conditions are 1 simultaneously (e.g.
d1
,
d2
,
d3
,
d4
and
d5
), only the instantaneously
effective input is handled. I.e. in each calculation cycle, switch-over is only by one step.
For realizing a sequencing with more than 10 steps, the STEP function can be cascaded:
The wiring example shows how 2 STEP functions are cascaded. With cascading, step number 1...n is output always as
a value at output
Step
of the last follow-up step.
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Logic functions
55 STEP (step function for sequencing)