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
217
5.7 Isochronous mode
5.7.1 What is isochronous mode?
Objectives of isochronous operation
The advantages of the isochronous mode function in automation engineering can be seen in
an example from everyday life.
The transmission of data corresponds to the transport of people on public transport.
Assuming public transport were to operate at maximum speed while reducing stop times at
the passenger terminals to absolute minimum, the last thing many potential passengers
would notice of the departing contraption are its red tail lights. The overall travel time is,
however, decided by the train, bus or underground-railway clock, because well adjusted
timing is essential to a good service. This also applies in automation engineering. Not only
fast cycles but also the adaptation and synchronization of the individual cycles result in
optimum throughput.
Just-In-Time
Figure 5-70 System cycle