Different Cycle Times - Siemens SIMATIC S7-400H System Manual

S7-400 cycle and response times

19.3 Different cycle times

19.3 Different cycle times
The cycle time (T
cycle times T
interrupted by a TOD interrupt OB (here: OB 10).
Figure 19-2
Fluctuation of the block processing time (e.g. OB 1) may also be a factor causing cycle time
fluctuation, due to:
● conditional instructions
● conditional block calls
● different program paths
● loops, etc.
Maximum cycle time
In STEP 7 you can modify the default maximum cycle time (scan cycle monitoring time). OB
80 is called when this time expires. In this block you can specify the CPUs response to this
time error. If you do not retrigger the cycle time with SFC 43, OB 80 doubles the cycle time
at the first call. In this case the CPU switches to STOP mode when OB 80 is called a second
time.
The CPU switches to STOP mode if OB 80 does not exist in its memory.
364
) length is not the same in every cycle. The figure below shows different
cyc
and T . T is longer than T
cyc1 cyc2 cyc2
Different cycle times
because the cyclically executed OB 1 is
cyc1
System Manual, 03/2012, A5E00267695-11
S7-400H