Siemens SINUMERIK 840D sl Configuration Manual page 93

4. In the "Cable length" dropdown list, enter the length of the actual cable in order to
minimize the signal run time.
5. Switch in the sector tree of the inspector window to the "PROFINET interface > Extended
options > Isochronous mode" entry.
6. Activate the "Isochronous operation" checkbox.
The isochronous operation of the device is activated and concurrently the synchronization
role of the device set to "sync slave" and the RT class set to "IRT" in the sync domain.
7. In the "Ti/To values" dropdown list, select "From the OB".
This causes the value to be taken automatically from the setting of the isochronous alarm
OB "NCK".
8. Activate the isochronous mode individually for the desired modules of the device in the
"Detail overview" table.
Figure 4-4 Settings for the isochronous mode using the example of a SINAMICS S120/S150 CU320-2
SINUMERIK STEP 7 Toolbox V14 SP1
Configuration Manual, 05/2017, A5E41846325
Configuring networks
4.5 Configuring PROFINET IO with IRT
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