Siemens SINAMICS S120 Series Function Manual page 127

IRT "high performance"
In addition to the bandwidth reservation, the telegram traffic can be further tuned by
configuring the topology. This enhances the performance during data exchange and the
deterministic behavior. The IRT time interval can thus be further tuned or minimized with
respect to IRT "high flexibility".
In addition to the isochronous data transfer provided by IRT, even the application itself
(position control cycle, IPO cycle) can be isochronous in the devices. This is an essential
requirement for closed-loop axis control and synchronization via the bus. 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 telegrams for PROFINET IO
with IRT are transferred according to a schedule.
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
Clock generation via PROFINET IO (isochronous communication)
SINAMICS S120 with CU310-2 PN/CU320-2 DP/CU320-2 PN can only assume the role of a
synchronization device within a PROFINET IO network.
For a CU310-2 PN/CU320-2 DP/CU320-2 PN with CBE20 module, the following applies:
● Transmission type IRT, IO device is synchronization slave and isochronous, send cycle is
applied to bus: Control Unit synchronizes with the bus and the send cycle becomes the
cycle for the Control Unit.
● RT or IRT (option drive unit "not isochronous") has been configured. SINAMICS uses the
local cycle configured in SINAMICS.
The following applies to a CU320-2 DP/CU320-2 PN for which a CBE20 is configured, but
does not actually exist:
● SINAMICS uses the local clock (clock configured in SINAMICS); if there is no data
exchange via PROFINET, alarm A01487 is output ("Topology: Comparison option slot
components missing in the actual topology").
Access via PROFINET is not available.
Communication
Function Manual, 12/2018, 6SL3097-5BD00-0BP0
Communication via PROFINET IO
5.2 RT classes for PROFINET IO
125