Siemens CPU 948, Programming Manual

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Cyclic timed interrupts On the CPU 948, you can process 9 different time-controlled
programs, each being called at a different cyclic interval.
Triggering
The basic clock pulse for timed interrupt processing is set to 100 ms.
Using a special parameter in data block DX 0, you can adjust this in
steps of 10 ms (basic clock pulse = yy
*
10 ms where: 01H
≤
yy
≤
FFH).
You can base the setting of the clock pulse on the shortest time
required by your application for cyclic processing.
Time interval Cyclic timed interrupts are processed at fixed intervals with 9 possible
intervals (periods). Each interval is assigned to a specific organization
block. You can select between two sets of intervals. You select the
sets of intervals using a special parameter in data block DX 0.
the following table illustrates the two sets of intervals with the
assignment of the different intervals to organization blocks.
Interval set 1
(default )
Interval set 2 OB called
1x basic clock pulse
2 x basic clock pulse
5 x basic clock pulse
10 x basic clock pulse
20 x basic clock pulse
50 x basic clock pulse
100 x basic clock pulse
200 x basic clock pulse
500 x basic clock pulse 1 x basic clock pulse
2 x basic clock pulse
4 x basic clock pulse
8 x basic clock pulse
16 x basic clock pulse
32 x basic clock pulse
64 x basic clock pulse
128 x basic clock pulse
256 x basic clock pulse OB 10
OB 11
OB 12
OB 13
OB 14
OB 15
OB 16
OB 17
OB 18
Note
The first TIMED INTERRUPT OB call following the start-up
takes place within the time assigned to the OB.
If, for example, the interrupt time "500 s" is set for OB 18 (basic
clock pulse setting in DX 0 = 1 s and time base = 1), then the first
OB 18 call takes place after approximately 20 s following a
COLD RESTART. All further calls are then at intervals of 500 s.
Table 4-5 Sets of intervals and intervals of the TIMED INTERRUPTS
RUN Mode
CPU 948 Programming Guide
C79000-G8576-C848-04
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