Siemens S7-300 Cycle control at the scan cycle check point CCP, Process Diagnostic Time-of-day

Cycle and reaction times 5.2 Cycle time

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 functions

•Transfer and deletion of blocks, compressing user program memory

•Communication

•Read/write access to the MMC, using SFC82 to 84

Table 5-6	Operating system processing time at the scan cycle checkpoint
CPU		Cycle control at the scan cycle check point (CCP)
312C		500 μs
313C		500 μs
313C-2		500 μs
314C-2		500 μs
312		500 μs
314		500 μs
315		500 μs
317		150 μs

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	Extended cycle time due to nested interrupts
Interrupt type		Process	Diagnostic	Time-of-day	Delay interrupt	Watchdog
		interrupt	Interrupt	interrupt		interrupt
312C		700 μs	700 μs	600 μs	400 μs	250 μs
313C		500 μs	600 μs	400 μs	300 μs	150 μs
313C-2		500 μs	600 μs	400 μs	300 μs	150 μs
314C-2		500 μs	600 μs	400 μs	300 μs	150 μs
312		700 μs	700 μs	600 μs	400 μs	250 μs
314		500 μs	600 μs	400 μs	300 μs	150 μs
315		500 μs	600 μs	400 μs	300 μs	150 μs
317		190 μs	240 μs	200 μs	150 μs	90 μs

The program runtime at interrupt level must be added to this time extension.

CPU 31xC and CPU 31x, Technical data	5-7
Manual, Edition 08/2004, A5E00105475-05