Operating instructions

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
143
6.2.4 Communication via BACnet MS/TP
BACnet properties
In BACnet, components and systems are considered to be black boxes which contain a
number of objects. BACnet objects only define behavior outside the device, internal functions
are not determined by BACnet.
Each component is represented by a series of object types and their instances.
Each BACnet device has precisely one BACnet device object. A BACnet device is clearly
identified by an NSAP (Network Service Access Point - comprising network number and
MAC address; MAC: Medium Access Control). This address is BACnet-specific and must not
be confused with the Ethernet MAC address.
Data exchange with the client
The inverter receives control commands and setpoints via service instructions from the
control and transmits its status back to the control. The inverter can also send telegrams
automatically itself, respectively execute services, e.g. I-Am.
Communication settings
● The Control Unit supports BACnet via RS485 (BACnet MS/TP)
● The maximum cable length is 1200 m (3281 ft).
Protocol Implementation Conformance Statement
You will find the Protocol Implementation Conformance Statement (PICS) in the Internet
under the following link: BACnet files
(http://support.automation.siemens.
com/WW/view/en/38439094)
CAUTION
It is not permitted to change over the units!
The "Unit changeover (Page 219)" function is not permissible with
this bus system!