Siemens SIMATIC ET 200pro - Update Process Image Partitions in the User Program

Configuring
5.2 Configuring the CPU
CPU 1516pro-2 PN (6ES7516-2PN00-0AB0)
Operating Instructions, 11/2019, A5E35873416-AC
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5.2.3.3 Update process image partitions in the user program
Requirements
Alternatively, you can also use the following instructions to update process images:
● "UPDAT_PI" instruction
● "UPDAT_PO" instruction
You will find the instructions in STEP 7 in the "Instructions" task card under "Extended
instructions". The instructions can be called from any point in the user program.
Requirements for updating process image partitions with the "UPDAT_PI" and "UPDAT_PO"
instructions:
● The process image partitions must not be assigned to any OB. This means the process
image partitions are not automatically updated.
Note
Updating PIP 0
PIP 0 (automatic update) cannot be updated with the "UPDAT_PI" and "UPDAT_PO"
instructions.
UPDAT_PI: Update 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 process image partition of the outputs
With this instruction you transmit the process image partition of the outputs to the output
modules.
Isochronous mode interrupt OBs
In synchronous cycle interrupt OBs you use the "SYNC_PI" and "SYNC_PO" instructions to
update the process image partitions. Additional information on isochronous mode interrupt
OBs is available in the STEP 7 online help.
Direct I/O access to the inputs and outputs of the module
You also have direct read and write access to the I/O, as an alternative to access via the
process image, should direct access be required for programming reasons. A direct (write)
I/O access also writes the process image. This prevents a subsequent output of the process
image from again overwriting the value written by direct access.
Reference
Additional information on process image partitions is available found in the function manual,
Cycle and response times (https://support.industry.siemens.com/cs/ww/en/view/59193558
).