Assign Process Image Partitions To An Ob - Siemens SIMATIC S7-1500 System Manual

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).
PIP 0 (automatic update) is automatically updated in each program cycle and is assigned to
OB 1.
Process image partitions PIP 1 through PIP 31 can be assigned to the other OBs. In
STEP 7, this assignment occurs during configuration of the I/O modules.
After the OB has been started, the assigned process image partition of inputs is updated by
the system and the process signals are read in. At the end of the OB the outputs of the
assigned process image partition are written directly to the peripheral outputs by the system
without having to wait for the termination of the cyclic program processing.
6.1.3.2

Assign process image partitions to an OB

Update process image partition
You can assign a process image partition to an OB. In this case, the process image partition
is automatically updated.
The process image partition of the inputs (PIPI) is always read in/updated before the
processing of the associated OB. The process image partition of the outputs (PIPQ) is
always output at the end of the OB.
The following figure illustrates the updating of a process image partition.
Figure 6-10
Automation system
System Manual, 09/2016, A5E03461182-AD
Update process image partitions
Configuring
6.1 Configuring the CPU
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