Siemens CPU 31 Series - Factors Extending Cycle Time

Cycle and reaction times
5.2 Cycle time
CPU 31xC and CPU 31x, Technical Data
Manual, 01/2006 Edition, A5E00105475-06
5-5
Table 5-4 CPU 31x: Data for calculating the process image (PI) transfer time
Const. Components CPU 312 CPU 314 CPU 315 CPU 317 CPU 319
C Base load 150 μs 100 μs 100 μs 50 μs 2 μs
A Per byte in the
rack 0
37 μs 35 μs 37 μs 15 μs 15 μs
B per byte in module
racks 1 to 3 *
- 43 μs* 47 μs* 25 μs* 22 μs**
D
(DP only)
Per word in the DP
area for the
integrated DP
interface
- - 2,5 μs 2,5 μs 2,5 μs
P
(PROFIN
ET only)
per WORD in the
PROFINET area
for the integrated
PROFINET
interface
- - 46 μs 46 μs 2,5 μs
* + 60 μs per rack
** + 21 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
319 1,05