Process Images And Process Image Partitions; Process Image - Overview - Siemens Simatic S7-1500R System Manual

6.5

Process images and process image partitions

6.5.1

Process image - overview

Process image inputs and outputs
The process image of the inputs and outputs is an image of the signal states. The CPU
transfers the values from the input and output modules to the process image inputs and
outputs. At the start of the cyclic program, the CPU transfers the process image output as a
signal state to the output modules. The CPU then transfers the signal states of the input
modules to the process image inputs.
Advantages of the process image
A process image accesses a consistent image of the process signals during cyclic program
execution. If a signal state at an input module changes during program execution, the signal
state is retained in the process image. The CPU does not update the process image until the
next cycle.
Consistency of the process image
When the process image is updated, the S7-1500R/H redundant system accesses the data
of each submodule as consistent data. This behavior is identical to that of S7-1500 CPUs.
The maximum data width that is accessed as consistent data for each submodule depends
on the IO system. For PROFINET IO, for example, this data width is 1024 bytes.
S7-1500R/H redundant system
System Manual, 10/2018, A5E41814787-AA
6.5 Process images and process image partitions
Configuration
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