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Configuring

7.2 Configuring the CPU

Distributed I/O system

140 System Manual, 09/2019, A5E03576849-AJ

7.2.3.2 Automatically updating process image partitions

You can assign one process image partition to each organization block. In this case, the user

program automatically updates the process image partition. The exceptions are PIP 0 and

isochronous OBs.

Updating the process image partition

The process image partition is divided into two parts:

● Process image partition of the inputs (PIPI)

● Process image partition of the outputs (PIPQ)

The CPU always updates/reads the process image partition of the inputs (PIPI) before

processing of the associated OB. The CPU outputs the process image of the outputs (PIPQ)

at the end of the OB.

The figure below illustrates the updating of the process image partitions.

Figure 7-8 Updating process image partitions

7.2.3.3 Update process image partitions in the user program

Requirements

Alternatively, you can also use the following instructions for the process image update:

● "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 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

Update of PPI 0

PIP 0 (automatic update) cannot be updated with the "UPDAT_PI" and "UPDAT_PO"

inst

ructions.

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