Table 16-3 Allocation Of The Process Image Transfer Time, Cpu 412-3H - Siemens SIMATIC S7-400H System Manual

S7-400 cycle and reaction times
16.2 Calculating the cycle time
Process image update
The table below shows the time a CPU requires to update the process image (process
image transfer time). The specified times only represent "ideal values", and may be
extended accordingly by any interrupts or communication of the CPU.
Calculation of the transfer time for process image update:
C+ portion in the central unit (taken from row A of the table below)
+ portion in the expansion unit with local link (from row B)
+ portion in the expansion unit with remote link (from row C)
+ portion via the integrated DP interface (from row D)
+ portion of consistent data via the integrated DP interface (from row E1)
+ portion of consistent data via external DP interface (from row E2)
= Transfer time for process image update
The tables below show the various portions of the transfer time for a process image update
(process image transfer time). The specified times only represent "ideal values", and may be
extended accordingly by any interrupts or communication of the CPU.
Table 16-3 Allocation of the process image transfer time, CPU 412-3H
Allocation
n = number in bytes in the process image
m = number of accesses to process image
K Base load
A In central unit
**)
Read/write byte/word/double word
B In expansion unit with local link
**)
Read/write byte/word/double word
C In expansion unit with remote link
**)***)
Read/write byte/word/double word
D In the DP area for the integrated DP interface
Read byte/word/double word
D In the DP area for the external DP interfaces
Read/write byte/word/double word
E1 Consistent data in the process image for the integrated DP
interface
Read/write data
E2 Consistent data in the process image for the external DP
interface (CP 443–5 extended)
read/write data
The module data is updated with the minimum number of accesses.
*)
(e.g.: 8 bytes result in 2 double word accesses, and 16 bytes in 4 double word accesses.)
In the case of I/O inserted into the central unit or into an expansion unit,
**)
the specified value contains the execution time of the I/O module
Measured with IM460-3 and IM461-3, at a link length of 100 m
***)
262
CPU 412-3H
stand-alone mode
*)
13 µs
m * 9.5 µs
m * 24 µs
m * 48 µs
m * 2.0 µs
m * 6.0 µs
n * 1.4 µs
n * 3.0 µs
CPU 412-3H
redundant
16 µs
m * 40 µs
m * 52 µs
m * 76 µs
m * 35 µs
m * 40 µs
n * 4.4 µs
n * 6.5 µs
System Manual, 09/2007, A5E00267695-03
S7-400H