Portions Of The Process Image Transfer Time - Siemens SIMATIC S7-400 Reference Manual

Process Image Updating
The table below shows the CPU times for process image updating (process image
transfer time). The times listed in the table are "ideal values" that may be increased
by the occurrence of interrupts and by CPU communications.
The transfer time for process image updating is calculated as follows
C + portion in central rack (from line A of the following table)
+ portion in expansion rack with local connection (from line B)
+ portion in expansion rack with remote connection (from line C)
+ portion via integrated DP interface (from line D)
+ portion of consistent data via integrated DP interface (from line E1)
+ portion of consistent data via external DP interface (from line E2)
= transfer time for process image updating
The following tables list the individual portions of the transfer times for updating the process
image (process image transfer time), once for standard CPUs and once for redundant CPUs.
The times listed in the table are "ideal values" that may be increased by the occurrence of
interrupts and by CPU communications.
Table 3-3

Portions of the process image transfer time

n = number of bytes in the process image
c= number of consistency areas
image
C Base load
*) **)
A In the central rack
B In the expansion rack with local connection
C In the expansion rack with remote connection
D In the DP area for the integrated DP interface
E Consistent data in the process image for the integrated DP
1 interface
E Consistent data in the process image for the external DP
2 interface (CP 443-5 extended)
*)
Also applies to the external DP interface (CP 443-5 extended)
**)
In the case of I/O modules that are plugged into the central rack or an expansion rack,
the specified value contains the runtime of the I/O module
***)
Measured with the IM 460-3 and IM 461-3 with a connection length of 100 m
****)
The areas set in HW Config that are written to or read from the I/O at once and are therefore
consistent.
Automation System S7-400 CPU Specifications
A5E00165965-01
Portions
****)
in the process
**)
**) ***)
Cycle and Reaction Times of the S7-400
CPU 412 CPU 414
CPU 417
30 ms 20 ms
n * 1.9 ms n * 1.9 ms
n * 5 ms n * 5 ms
n * 10 ms n * 10 ms
n * 0.5 ms n * 0.5 ms
k * 40 ms k * 27 ms
+ n * 0.5 ms + n * 0.5 ms
k * 40 ms k * 27 ms
+ n * 3.2 ms + n * 3.2 ms
CPU 416
18 ms
n * 1.9 ms
n * 5 ms
n * 10 ms
n * 0.5 ms
k * 22 ms
+ n * 0.5 ms
k * 22 ms
+ n * 2.1 ms
3-5