Siemens Simatic S7-300 Technical Data Manual page 89

Operating system processing time at the scan cycle checkpoint
The table below shows the operating system processing time at the scan cycle checkpoint of
the CPUs. These times are calculated without taking into consideration times for:
• Testing and commissioning routines, e.g. status/controlling of variables or block status
• Transfer and deletion of blocks, compressing user program memory
• Communication
• Read/write access to the MMC, using SFC82 to 84
Table 5-6
CPU
312C
313C
313C-2
314C-2
312
314
315
317
Extension of the cycle time as a result of nested interrupts
Enabled interrupts also extend cycle time. Details are found in the table below.
Table 5-7
Interrupt type
312C
313C
313C-2
314C-2
312
314
315
317
The program runtime at interrupt level must be added to this time extension.
CPU 31xC and CPU 31x, Technical data
Manual, Edition 08/2004, A5E00105475-05
functions
Operating system processing time at the scan cycle checkpoint
Extended cycle time due to nested interrupts
Process
interrupt
700 μs
500 μs
500 μs
500 μs
700 μs
500 μs
500 μs
190 μs
Cycle control at the scan cycle check point (CCP)
500 μs
500 μs
500 μs
500 μs
500 μs
500 μs
500 μs
150 μs
Diagnostic Time-of-day
Interrupt interrupt
700 μs 600 μs
600 μs 400 μs
600 μs 400 μs
600 μs 400 μs
700 μs 600 μs
600 μs 400 μs
600 μs 400 μs
240 μs 200 μs
Cycle and reaction times
5.2 Cycle time
Delay interrupt Watchdog
interrupt
400 μs 250 μs
300 μs 150 μs
300 μs 150 μs
300 μs 150 μs
400 μs 250 μs
300 μs 150 μs
300 μs 150 μs
150 μs 90 μs
5-7