Configuring
7.1 Configuring the CPU
Automation system
System Manual, 12/2017, A5E03461182-AE
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7.1.3
Process images and process image partitions
7.1.3.1
Process image - overview
Process image of the 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 in this memory
area. At the start of the cyclic program, the CPU transfers the signal states of the input
modules to the process image input. At the end of the cyclic program, the CPU transfers the
process image output as a signal state to the output modules.
Advantages of the process image
A process image allows you to access a consistent image of process signals during cyclic
program execution. If a signal state at an input module changes during program processing,
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 S7-1500 accesses the data of each submodule as
consistent data. The maximum data width that is accessed as consistent data for each
submodule is dependent on the IO system. For PROFINET IO, for example, this data width
is 1024 bytes.
32 process image partitions
By means of process image partitions, the CPU synchronizes the updated inputs/outputs of
particular modules with defined user program sections.
In the S7-1500 automation system, the overall process image is subdivided into up to 32
process image partitions (PIP).
The CPU automatically updates PIP 0 (automatic update) in each program cycle and assigns
it to OB 1.
You can assign the process image partitions PIP 1 to PIP 31 to the other OBs during
configuration of the input/output modules.
After the OB has been started, the CPU updates the assigned process image partition for
inputs and reads in the process signals. At the end of the OB, the CPU writes the outputs of
the assigned process image partition directly to the peripheral outputs by the system without
having to wait for the completion of the cyclic program processing.
Summary of Contents for Simatic S7-1500/ET 200MP
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