Siemens SINAMICS DCM Operating Instructions Manual page 384

Descriptions of functions
10.3 PROFINET IO
2) It is generally only possible to set a reduction ratio of 1:1 between the update time and
send cycle for IO devices (ET200S IM151-3 PN HS, SINAMICS S) which are operated in the
isochronous mode. In this case, the update time mode must always be set to "fixed factor"
(under "I/O device" properties, "IO cycle" tab, "Mode" pulldown menu). This means that
STEP 7 will not automatically adjust the update time and, therefore, that the update time will
always correspond to the send cycle.
3) The send cycles from the "uneven" range can be set only if a synchronization domain
does not include any IO devices with RT class "RT". Likewise, only the reduction ratios from
the "uneven" range can be set for a send cycle setting from the "uneven" range.
4) Isochronous operation is not compatible with IRT "high flexibility".
5) Uneven send cycles can be used only if the IO systems assigned to the synchronization
domain do not include any RT or IRT "high flexibility" devices.
Furthermore, the send cycles which can actually be set are determined by the intersection
between the send cycles supported by all the devices in the synchronization domain.
The reduction ratio between the update time of an IO device and the send cycle is set in the
"Properties" of the PROFINET interface for the relevant device.
Send cycles for SINAMICS drive units
A SINAMICS drive unit with PROFINET interface which supports IRT permits send cycle
settings of between 0.5 ms and 4.0 ms in a 250 µs time frame.
Topology rules
Topology rules for RT
● A topology can be configured for RT, but does not need to be. If a topology has been
● Apart from this stipulation, the devices can be wired in any way you wish.
Topology rules for IRT
● Mixed operation is not supported by STEP 7 V5.4 SP4, i.e. IRT "high performance"
● A synchronization domain with IRT "high performance" can contain a maximum of one
● IRT "high flexibility" is subject to the same topology rules as IRT "high performance", the
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configured, the devices must be wired in accordance with the topology.
cannot be combined with IRT "high flexibility" in the same synchronization domain.
IRT "high performance" island. An "island" refers to the fact that the devices must be
interconnected to match the configured topology. A synchronization master must be
positioned in the relevant island.
only exception being that a topology does not need to be configured. However, if a
topology has been configured, the devices must be wired to match the topology.
Operating Instructions, 1.2012, C98130-A7066-A1-05-7619
SINAMICS DCM DC Converter