Operation
6.8 PROFINET IO
Drive converter cabinet units
252 Operating Instructions, 07/07, A5E00288214A
6.8.4.2 PROFINET IO with RT
PROFINET IO with RT is the optimal solution for the integration of I/O systems without
particular requirements in terms of performance and isochronous mode. This is a solution
that also uses standard Ethernet in the devices and commercially available industrial
switches as infrastructure components. A special hardware support is not required.
Not isochronous
Because standard Ethernet does not support any synchronization mechanisms, isochronous
operation is not possible with PROFINET IO with RT!
The realtime capability is comparable with the present PROFIBUS DP solutions with 12
MBaud, whereby a sufficiently large bandwidth portion is available for the parallel
transmission of IT services on the same line.
PROFINET IO telegrams have priority over IT telegrams in accordance with IEEE802.1q.
This ensures the required determinism in the automation technology.
Data exchange
Communication is possibly only within a network (subnet).
Refresh time
The refresh time is in the range 1 ms, 2 ms and 4 ms. The real refresh time depends on the
bus load, the devices used and the quality structure of the I/O data. The refresh time is a
multiple of the send clock.
6.8.4.3 Configuring RT communication on Simatic
RT communications with GSDML v1.0
Requirement
For example, a Simatic 300 CPU version <2.5 is configured with a PROFINET sub-network,
and a drive is inserted via the GSD file SINAMICS S120 CBE20 Pilot RT.
Now, drives and drive objects (DOs) are to be parameterized. For this version of the drive,
the telegrams must be inserted step-by-step. To start, a Parameter Access Point must be
inserted, then a telegram and then again another Parameter Access Point - and so on.
Note
The sequence in which the telegram is created must be the same as the sequence of the
drive objects in the configuration screen for the drive in STARTER.
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