Siemens Sinamics S120 Function Manual page 642

Communication
10.3 Communication via PROFINET IO
Comparison between RT and IRT
Table 10- 60 Comparison between RT and IRT
RT class
Transfer mode
Isochronous application
in the IO controller
Determinism
Reload the network
configuration after a change
Maximum switching depth
(number of switches in one
line)
For possible send cycles, see subitem "Send cycles and update cycles for RT classes" in table "Adjustable send cycles
and update cycles"
Set the RT class
The RT class is set by means of the properties of the controller interface of the IO controller.
If RT class IRT "high performance" is set, it is not possible to operate any IRT "high
flexibility" devices on the IO controller and vice versa. IO devices with RT can always be
operated, regardless of the IRT class setting.
You can set the RT class in the HW Config for the associated PROFINET device.
1. In HW Config, double-click on item PROFINET interface in the module.
2. Select the RT class under RT class on the "Synchronization" tab.
3. Once you have selected "IRT", you can also choose between option "high flexibility" and
4. Confirm with "OK".
640
RT
Switching based on the MAC
address; prioritization of the
RT telegrams possible using
Ethernet-Prio (VLAN tag)
No
Variance of the transmission
duration by started TCP/IP
telegrams
Not relevant
10 at 1 ms
The "Properties" dialog box is opened.
"high performance".
IRT "high flexibility"
Switching using the MAC
address;
bandwidth reservation by
reserving an IRT "high
flexibility" interval in which
only IRT "high flexibility"
frames are transferred but,
for example, no TCP/IP
frames
No
Guaranteed transmission of
the IRT "high flexibility"
telegrams in the current
cycle by the reserved
bandwidth.
Only when the size of the
IRT "high flexibility" interval
needs to be modified
(reservation of position is
possible)
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Function Manual, (FH1), 01/2012, 6SL3097-4AB00-0BP2
IRT "high performance"
Path-based switching
according to a topology-
based plan; no transmission
of TCP/IP frames and IRT
"high flexibility" frames in the
IRT "high performance"
interval.
Yes
Exactly planned transfer;
times for transmission and
receiving are guaranteed for
any topologies.
Whenever the topology or
the communication
relationships
change
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Drive functions