Efficient Networks Siemens Sinamics S120 - Manual (Page 445)

Communication PROFIBUS DP/PROFINET IO
10.3 Communications via PROFINET IO
Drive Functions
Function Manual, (FH1), 07/2007 Edition, 6SL3097-2AB00-0BP4
445
RT class RT IRTtop
Maximum switching depth (number of
switches in one line)
10 at 1 ms 20
Synchronization accuracy - Forwarding of the sync message frame
in software.
Accuracy <1 µs
Possible transmission cycle clocks
(observe any device-specific
restrictions)
500 (as of FW2.5 SP1), 1,000, 2,000,
4,000 µs
500 (as of FW2.5 SP1), 1,000 – 4,000
µs in increments of 125 µs. The
increment depends on the controller.
Set RT class
The IO controller determines which RT class its IO system supports, by setting the real time
class at its controller interface. If IRTtop is set, it is not possible to operate any IRTflex
devices on the IO controller and conversely. RT devices can always be operated, even if IRT
classes are set.
You can set the RT class in the HW Config for the associated PROFINET device.
1. Double-click on the PROFINET board entry in the module in HW Config.
The "Properties" dialog box is opened.
2. Select the realtime class for RT class in the Synchronization tab.
3. Confirm with "OK".
10.3.3.2 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 message frames have priority over IT message frames in accordance with
IEEE802.1q. This ensures the required determinism in the automation technology.
Data exchange
Communication is possibly only within a network (subnet).