Assign Process Image Partitions To An Ob; Update Process Image Partitions In The User Program - Siemens SIMATIC S7-1500 System Manual

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 the process image partitions.
Figure 6-10
6.1.3.3

Update process image partitions in the user program

Requirements
As an alternative to the automatic updating and to updating by assignment to an OB, you
can use the instruction "UPDAT_PI" or the instruction "UPDAT_PO" at the start or the at the
end of the respectively assigned OB to update the process image. In STEP 7, these
instructions are available on the "Instructions" Task Card under "Extended instructions" and
may be called from any point in the program.
Requirements for updating process image partitions with the "UPDAT_PI" and "UPDAT_PO"
instructions:
● The process image partitions may not be assigned to any OB, i.e. they may not be
automatically updated.
● PIP 0 (automatic update) can likewise not be updated with the "UPDAT_PI" and
"UPDAT_PO" instructions.
UPDAT_PI: Update the process image partition of the inputs
With this instruction you read the signal states from the input modules into the process
image partition of the inputs (PIPI).
UPDAT_PO: Update the process image partition of the outputs
With this instruction you transmit the process image partition of the outputs to the output
modules.
Automation system
System Manual, 12/2014, A5E03461182-AC
Update process image partitions
Configuring
6.1 Configuring the CPU
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