Communication Via Uss; Basic Settings For Communication - Siemens Sinamics G120P Operating Instructions Manual

Operation
6.8 Communication via RS485
Communication with the controller even when the supply voltage on the Power Module is
switched off
You must supply the Control Unit with 24 VDC at terminals X9:1,2 on the Power Module if
you wish to maintain communication with the controller even when the line voltage is
switched off.
In the case of short interruptions of the 24 V voltage supply, the inverter may report a fault
without communications with the controller being interrupted.
6.8.2

Communication via USS

The USS protocol is a serial-data connection between one master and one or more slaves. A
master is, for example:
● A programmable logic controller (e.g. SIMATIC S7-200)
● A PC
The inverter is always a slave.
A maximum of 31 slaves is possible.
The maximum cable length is 100 m.
Information about how to connect the inverter to the USS fieldbus is provided in Section
Integrating inverters into a bus system via the RS485 interface (Page 217).
6.8.2.1

Basic settings for communication

Setting the address
You set the bus address of the inverter using the
address switches on the Control Unit, using parame-
ter p2021 or in STARTER.
Valid address range:
If you have specified a valid address using the ad-
dress switches, this address will always be the one
that takes effect, and parameter p2021 (factory set-
ting: 0) will not be able to be changed.
The positions of the address switches are described
in Section: CU230P-2 HVAC Control Unit (option
K98) (Page 87).
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Inverter cabinet units
Operating Instructions, 12/2014, A5E32923362A