Efficient Networks Siemens Sinamics S120 - Manual (Page 446)

Communication PROFIBUS DP/PROFINET IO
10.3 Communications via PROFINET IO
Drive Functions
446
Function Manual, (FH1), 07/2007 Edition, 6SL3097-2AB00-0BP4
Refresh time
The refresh time is in the range of 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.
10.3.3.3 PROFINET IO with IRT - Overview
Overview
PROFINET IO with IRT distinguishes itself through the separate time domains for IRT, RT
and TCP/IP communication. This is ensured by high-precision hardware-supported cycle
monitoring.
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PROFINET IO with IRT is available in two versions:
● IRTflex (flexible) with fixed bandwidth reservation (not available in FW2.5 SP1)
● IRTtop (top performance) with planned IRT communication
Time synchronization and isochronous mode on PROFINET IO with IRTtop
In addition, a high-performance and isochronous connection to the application with low load
on the application CPU is also ensured. Isochronous data transfer with cycle times well
below one millisecond and with a deviation in the cycle start (jitter) of less than a
microsecond provide sufficient performance reserves for demanding motion control
applications.
In contrast to standard Ethernet and PROFINET IO with RT, the message frames for
PROFINET IO with IRT are transmitted as scheduled.
Sync domain
The sync domain can be configured in the HW Config. SINAMICS S120 is an IO device and
must be assigned to a sync master as a sync slave.