Siemens SINAMICS Configuration Manual page 138

Communication
A.1 Communication
Cyclic communication using PROFINET IO with IRT or using RT is possible on all drive units
equipped with a PROFINET interface. This means that error-free communication using other
standard protocols is guaranteed within the same network.
Note
PROFINET for drive technology is standardized and described in the following document:
PROFIBUS profile PROFIdrive - Profile Drive Technology
Version V4.1, May 2006
PROFIBUS User Organization e. V.
Haid-und-Neu-Straße 7
D-76131 Karlsruhe
Internet: (http://www.profibus.com)
Order no. 3.172, spec. Ch. 6
● IEC 61800-7
Note
For CU320-2 DP with inserted CBE20, the cyclic PZD channel for PROFIBUS DP is
deactivated. When setting parameter p8839 = 1, the PZD channel can be reactivated (see
chapter "Parallel operation of communication interfaces (Page 90)").
Real-time (RT) and isochronous real-time (IRT) communication
Real-time communication
When communication takes place via TCP/IP, the resultant transmission times may be too
long and not defined to meet the production automation requirements. When communicating
time-critical IO user data, PROFINET IO therefore uses its own real-time channel, rather than
TCP/IP.
Real time means that a system processes external events over a defined period.
Determinism
Determinism means that a system will react in a predictable ("deterministic") manner.
With PROFINET IO with IRT, it is possible to precisely determine (predict) transmission times.
PROFINET IO with RT (Real Time)
Real-time data is treated with a higher priority than TCP(UDP)/IP data. Transmission of time-
critical data takes place at guaranteed time intervals. RT communication provides the basis
for data exchange with PROFINET IO.
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Configuration Manual, 08/2017, A5E36912609A
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