Siemens SIMATIC ET 200AL, System Manual

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Functions
5.7 Isochronous mode
PROFINET with STEP 7
Function Manual, 05/2021, A5E03444486-AL
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5. If required, insert additional IO devices in the network view. Adapt the configuration and the
settings for the isochronous mode.
6. You want to retrieve information about calculated bandwidths or on adapting the send
clock. Select the sync domain in the network view and navigate to the corresponding area of
the domain management in the Inspector window.
Reference
You can find examples of parameter assignment and possible settings of isochronous mode
for distributed I/O and drives in STEP 7 in this FAQ on the Internet
( https://support.industry.siemens.com/cs/ww/en/view/109480489 ).
5.7.4.3 Setting the application cycle and delay time
Requirements
• You have created an isochronous mode configuration in STEP 7.
• You have created an isochronous mode interrupt OB Synchronous Cycle (OB 6x).
• The isochronous mode interrupt OB is open.
Setting the application cycle
The application cycle is a multiple of data cycle T_DC (send clock). You use the application
cycle setting to reduce the CPU utilization caused by execution of the isochronous mode
interrupt OB. In the following example, the OB is called only after every 2nd data cycle T_DC
in the CPU.
To set the application cycle for your isochronous mode application, follow these steps:
1.
Open the "Properties" dialog of the isochronous mode interrupt OB under consideration.
2. In the area navigation, click the "Isochronous mode" group .
3. Set the application cycle in "Application cycle (ms)". Open the drop-down list box and select
the application cycle. The drop-down list offers multiples of data cycle T_DC as possible
values for the application cycle. Data cycle T_DC is set to 2 ms in the following figure.
Figure 5-74 Setting the application cycle