Siemens SIMATIC PROFINET Function Manual page 190

Functions
5.7 Isochronous mode
Procedure
To create an isochronous connection between the I/O and user program, follow these steps:
1. Select the "IM 155-5 PN HF" in the network view of STEP 7 and switch to the device
view.
2. Insert an IO module that can be operated in isochronous mode (module with the
extension "HF").
3. Go to the "I/O addresses" area in the Inspector window of the selected I/O module.
Figure 5-70 Configuring isochronous mode in STEP 7
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PROFINET with STEP 7 V14
Function Manual, 09/2016, A5E03444486-AG