Technical data

CU230P-2 Control Units, Getting Started
A5E02484096, 05/2009
7
3.4 Connecting the CU230P-2 HVAC via the RS485 interface
Description
This section describes how the inverter is physically connected to a serial bus
system over the RS485 interface. The communication settings are described in
the Control Unit operating instructions in the sections "Communication over USS"
and "Communication over Modbus RTU".
The Control Unit has a two-part terminal strip underneath the Control Unit which
allows the inverter to be integrated into a serial bus system over the RS485
interface. This connector has short-circuit-proof, isolated pins. You will find the
terminal assignments in the following table.
XXY
Z
56
FRQQHFWRU
3LQ
3LQ
%XV
WHUPLQDWLQJVZLWFK
Table 1 Assignments for the terminal strip of the RS485 interface
Contact Designation Description
1 0 V Reference potential
2 RS485P Receive and send signal (+)
3 RS485N Receive and send signal (-)
4 Shield Cable shield
5 --- ---
Communication settings
USS 4 = 2400
9 = 57600
5 = 4800
10 = 76800
6 = 9600
11 = 93750
7 = 19200
12 = 115200
8 = 38400
13 = 187500
Baud rate
p02020
Modbus RTU 5 = 4800 6 = 9600 7 = 19200
USS 0 … 30, factory setting = 8, maximum 31 Slaves Address
p2021
Modbus RTU 1 … 247, factory setting = 7, maximum 247 Slaves
Maximum cable length 1200 m (3281 ft)
General specifications and requirements for fault-free communication
NOTICE
When the bus is operating, the first and last bus station must be continuously connected to the supply.
Note
Communication with the controller, even when the supply voltage on the Power Module is switched off
You will have to supply the Control Unit with 24 V DC on terminals 31 and 32 if you require communication to take place with
the controller when the line voltage is switched off.
For the first and last stations, you must connect the bus terminating resistor using the DIP switches to the right of the RS485
terminal strip.
You can disconnect one or more slaves from the bus (by unplugging the bus connector) without interrupting the
communication for the other stations, but not the first or last.