Configuring the fieldbus
6.2 Communication via RS485
Frequency inverters with Control Units CU230P-2 HVAC, CU230P-2 DP, CU230P-2 CAN
Operating Instructions, 01/2011, FW 4.4, A5E02430659B AD
119
6.2.2
Communication via USS
Using the USS protocol (protocol of the universal serial interface), users can set up a serial
data connection between a higher-level master system and several slave systems (RS 485
interface). Master systems include programmable logic controllers (e.g. SIMATIC S7-200) or
PCs. The inverters are always slaves on the bus system.
Communication using the USS protocol takes place over the RS485 interface with a
maximum of 31 slaves.
The maximum cable length is 1200 m (3300 ft)
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 118).
6.2.2.1
Setting the address
You can set the inverter's USS address using either DIP switches on the Control Unit or
parameter p2021.
Valid USS addresses:
1 … 30
Invalid USS addresses:
0, 31 … 127
If you have specified a valid address using DIP switches, this address will always be the one
that takes effect and p2021 cannot be changed.
If you set all DIP switches to "OFF" (0) or "ON" (1), then p2021 defines the address.
The positions and settings of the DIP switches are described in Section Interfaces,
connectors, switches, control terminals, LEDs on the CU (Page 46).
CAUTION
A bus address that has been changed is only effective after the inverter has been switched
off and back on again.
Summary of Contents for SINAMICS G120 CU230P-2
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