Siemens SINAMICS S120 Function Manual page 720

Communication
11.3 Communication via PROFINET IO
Modules
The following S110/S120 modules support the IRT "high performance":
● S120 CU320 together with the CBE20
● S120 CU320-2 DP together with the CBE20
● S120 CU320-2 PN
● S120 CU310 PN
● S120 CU310-2 PN
● S110 CU305 PN
Comparison between RT and IRT
Table 11- 13 Comparison between RT and IRT
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"
720
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
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), 04/2014, 6SL3097-4AB00-0BP4
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.
Always when the topology or
the communications
relationships change.
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