Siemens SIMATIC S7-300 Series

Cycle and Reaction times
3-10
PLC S7-300, CPU Specifications CPU 312 IFM to CPU 318-2 DP
A5E00111190-01
Extending the Cycle by Nesting Interrupts
Table 3-6 shows typical extensions of the cycle time through nesting of an
interrupt. The program runtime at the interrupt level must be added to these. If
several interrupts are nested, the corresponding times need to be added.
Table 3-6 Extending the Cycle by Nesting Interrupts
Interrupts
312 IFM 313 314 314 IFM 315 315-2 DP 316-2DP 318-2
Hardware
<FJ>interr
upt
approx.
840 s
approx.
700 s
approx.
700 s
approx.
730 s
approx.
480 s
approx.
590 s
approx.
590 s
approx.
340ms
Diagnostic
interrupt
– approx.
880 s
approx.
880 s
approx.
1000 s
approx.
700 s
approx.
860 s
approx.
860 s
approx.
450 s
Time–of–d
ay
interrupt
– – approx.
680 s
approx.
700 s
approx.
460 s
approx.
560 s
approx.
560 s
approx.
350 s
Delay
interrupt
– – approx.
550 s
approx.
560 s
approx.
370 s
approx.
450 s
approx.
450 s
approx.
260 s
Watchdog
interrupt
– – approx.
360 s
approx.
380 s
approx.
280 s
approx.
220 
approx.
220 
approx.
260 s
Programm
ing/
access
error/
program
execution
error
– approx.
740 s
approx.
740 s
approx.
760 s
approx.
560 s
approx.
490 s
approx.
490 s
approx.
130/ 155/
285 s
3.3 Calculation Examples for Cycle Time and Response Time
Component Parts of the Cycle Time
As a reminder: The cycle time comprises:
 process image transfer time +
 operating system processing time +
 user program processing time +
 Processing time of S7 timers