Siemens SINAMICS S150, Руководство по эксплуатации

Страница: 257 / 520

Operation
6.8 PROFINET IO
Drive converter cabinet units
Operating Instructions, 07/07, A5E00288214A
257
Compatibility
A sync domain can only contain either IRTtop devices or IRTflex devices.
The communication between and through different sync domains over PROFINET RT is
possible. If no topology is configured, it is not necessary to observe a topology when
assembling the devices, as opposed to IRTtop, where devices must connected one to
another according to the configured topology.
6.8.4.6 PROFINET IO with IRTtop
The performance capability is significantly increased with PROFINET IRTtop for motion
control applications. A hardware support enables a significant increase in performance
compared with the present field bus solutions. By planning the telegram traffic in time for
IRTtop, a considerable data traffic optimization is achieved compared with IRTflex.
IRTtop is particularly suited for:
●
The control and synchronization of axes via PROFINET
● A fast, isochronous I/O integration with short terminal-terminal times
For PROFINET IO with IRTtop, the synchronization of all devices on a shared Sync master
is necessary. All synchronized devices combined form a sync domain.
Send clock/Refresh time
Within this time all cyclic and acyclic data (IRTtop data) is transferred. The send clock of 500
µs (planned as of FW2.5 SP1)/1 ms - 4 ms is the maximum range in which the send clock
can be set. The actual send clock that can be set depends on various factors:
●
The bus traffic load
● The type of devices used
● The computing power available in the controller
● The supported send clocks on the PROFINET devices involved in a sync domain.
A typical send clock is, for example, 1 ms. It can be set in a 125 µs grid within the limits of
500 µs (planned as of FW2.5 SP1)/1 ms to 4 ms.
Time-scheduled data transmission
Scheduling is the specification of the communication paths and the exact transmission times
for the data to be transferred. The bandwidth can be optimally utilized through
communication scheduling and therefore the best possible performance achieved. The
highest determinism quality is achieved through the scheduling of the transmission times
which is especially advantageous for an isochronous application connection.
The communication scheduling is performed by the engineering system. An IRT planning
algorithm is available for this. The schedule results must be transferred to each IO controller
through a download. The IO controller then loads the schedule results into the IO devices
during ramp-up. The communication with IRTtop is performed on the basis of these schedule
data.