Fast Forwarding - Siemens SIMATIC ET 200AL System Manual

Functions
5.6 PROFINET with performance upgrade
The following figure shows how fragmentation works.
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②
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Figure 5-57
Note
The PROFINET IO interface of the IO controller supports fragmentation if all the ports except
one are deactivated.
5.6.3

Fast forwarding

To be able to decide whether a frame should be forwarded or used, a PROFINET IO device
requires the frame ID. It previously took 1440 ns until the frame ID was present in the IO
device.
The performance upgrade uses the fast forwarding procedure in which the frame ID is
located nearer the front of the frame. The throughput time in the device is reduced to 320 ns.
With fast forwarding, the throughput time of the frame is reduced in your PROFINET IO
system. This results in decisive performance advantages, particularly in line, ring and tree
topologies.
192
A standard Ethernet frame with TCP/IP data is up to 125 µs.
During fragmentation, the standard Ethernet frame is divided into frame segments.
The frame segments are divided into multiple short send clocks.
Fragmentation
PROFINET with STEP 7 V15
Function Manual, 12/2017, A5E03444486-AH