Siemens S7-300 Extending the user program processing time, + 60 μs per rack, Const Portions CPU

Cycle and reaction times 5.2 Cycle time

Table 5-4	CPU 31x: Data for calculating the process image (PI) transfer time
Const.	Portions	CPU 312	CPU 314	CPU 315	CPU 317
K	Base load	150 μs	100 μs	100 μs	50 μs
A	per byte in module	37 μs	35 μs	37 μs	15 μs
	rack 0
B	per byte in module	-	43 μs	47 μs	25 μs
	racks 1 to 3 *
D	per WORD in the DP	-	-	1 μs	1 μs
(DP only)	area for the integrated
	DP interface
P	per WORD in the	-	-	46 μs	46 μs
(PROFINET	PROFINET area for
only)	the integrated
	PROFINET interface

*+ 60 μs per rack

*+ 60 μs per rack

Extending the user program processing time

In addition to actually working through the user program, your CPU's operating system also runs a number of processes in parallel

such as timer management for the core operating system. These processes extend the processing time of the user program. The table below lists the multiplication factors required to calculate your user program processing time.

Table 5-5	Extending the user program processing time
CPU		Factor
312C		1,06
313C		1,10
313C-2DP		1,10
313C-PtP		1,06
314C-2DP		1,10
314C-2PtP		1,09
312		1,06
314		1,10
315		1,10
317		1,07

5-6	CPU 31xC and CPU 31x, Technical data
	Manual, Edition 08/2004, A5E00105475-05