Siemens SIMATIC ET 200AL, System Manual

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Functions
5.6 PROFINET with performance upgrade
PROFINET with STEP 7
214
Function Manual, 05/2021, A5E03444486-AL
Requirements for the fragmentation process (example CPU 1518-4 PN/DP)
If you use the following combinations for send clock and bandwidth settings, the devices in
the IO system use the fragmentation process.
•
Send clock cycle 125 µs: Always fragmentation irrespective of the bandwidth setting.
• Send clock cycle 187.5 µs: Fragmentation with the bandwidth settings "Maximum 50%
cyclic IO data. Balanced proportion." and "Maximum 90% cyclic IO data. Focus on cyclic
IO data."
The PROFINET IO interface of the controller supports fragmentation if all the ports except one
are deactivated.
Optimizing port settings for low send clocks
You can further optimize the bandwidth use in your PROFINET IO system by using cables with
a short cable length (< 20 m) or a short signal delay (max. 0.12 µs) between the devices.
To configure cables with a shorter length or signal delay in STEP 7, follow these steps:
1.
Select the port in the topology view of STEP 7.
2. Navigate in the Inspector window to "Port interconnection" in the "Partner port" box.
3. Select the option "Cable length" or "Signal delay:".
4. Select the cable length or enter the signal delay.
Figure 5-67 Optimizing port settings for low send clocks