Siemens SIMATIC S7-1500 System Manual page 147

Configuring
7.11 Configuring the clock system
6. Assign the configured output under "Output".
Figure 7-37 Assigning a channel to the output cam
7. Use the "Device configuration" button to switch back to the CPU settings and check the
settings under "DI/DQ 8x24VDC [X142]" > "I/O addresses".
The following settings must be configured for the input and output addresses:
– "Isochronous mode" is enabled.
– The organization block "MC Servo" is selected.
– The process image "OB Servo PIP" is selected.
Automatic settings
Isochronous mode is mandatory for certain operating modes of the X142 technology I/O
channels.
As soon as you set one of the following operating modes for a technology I/O channel, STEP
7 automatically selects the option "isochronous mode".
● Timer DI
● Timer DQ
● Oversampling DI
● Oversampling DQ
● Event/period measurement
If you assign an output cam, cam track or measuring input technology object to an X142 I/O,
STEP 7 automatically sets the process image "OB Servo PIP".
In all other cases, you set the process image manually. If isochronous mode is mandatory for
at least one technology I/O, you must set the process image of the "MC Servo" OB (OB91)
or an isochronous mode interrupt OB (OB6x).
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SIMATIC Drive Controller
System Manual, 11/2019, A5E46600094-AA