Siemens CPU 31 Series - Different Cycle Times

Cycle and reaction times
5.2 Cycle time
CPU 31xC and CPU 31x, Technical Data
Manual, 01/2006 Edition, A5E00105475-06
5-7
Extension of the cycle time due to error
Table 5-8 Cycle time extension as a result of errors
Type of error Programming errors I/O access errors
312C 600 μs 600 μs
313C 400 μs 400 μs
313C2 400 μs 400 μs
314C-2 400 μs 400 μs
312 600 μs 600 μs
314 400 μs 400 μs
315 400 μs 400 μs
317 100 μs 100 μs
319 19 μs 23 μs
The interrupt OB processing time must be added to this extended time. The times required
for multiple nested interrupt/error OBs are added accordingly.
5.2.3 Different cycle times
Overview
The cycle time (T
cyc
) length is not the same in every cycle. The figure below shows different
cycle times T
cyc1
and T
cyc2
. T
cyc2
is longer than T
cyc1
, because the cyclically executed OB1 is
interrupted by a time-of-day interrupt OB (here: OB 10).
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