Concept
KNX Modbus Gateway Screw Terminals and Connector
The KNX Modbus gateway (RP-C-EXT-KNX) is equipped with two 3-position pluggable screw terminal blocks for connection to the RP-C Modbus (RS-485) network and a 2-pole PCB connector for connection to the KNX bus.
You need to configure which RS-485 port (RJ45) on the RP-C controller to use for the Modbus network. You can configure to use either the Sensor Bus port or Room Bus port. For more information, see RP-C Communication Ports .
Screw terminals and connector, KNX Modbus gateway
The upper and lower screw terminal blocks are used as follows:
Upper: Power input from the RP-C through the controller's RS-485 port
Lower: Communication with the RP-C over the controller's Modbus network
|
Terminal number |
Designation |
Usage |
RP-C RS-485 Port RJ45 Pin |
|
Power input |
|
|
|
|
1 |
– |
Ground connection for supply voltage from the RP-C. |
5 a |
|
2 |
– |
Ground connection for supply voltage. Not connected to the RP-C. |
- |
|
3 |
+ |
Positive connection for supply voltage (24 VDC) from the RP-C. |
4, 7 |
|
Modbus |
|
|
|
|
4 |
– |
Ground connection for Modbus communication with the RP-C. |
8 a |
|
5 |
A |
Data line A (RS485+) for Modbus communication with the RP-C. |
3 |
|
6 |
B |
Data line B (RS485–) for Modbus communication with the RP-C. |
6 |
- RJ45 pins 5 and 8 are internally connected.
The KNX Modbus gateway uses a 4-conductor, 2-pole KNX connector for connection to the KNX bus.
|
Connector color |
Designation |
Usage |
|
Red |
+ |
Positive connection to KNX bus |
|
Dark gray |
– |
Ground connection to KNX bus |
KNX Modbus Gateway RP-C-EXT-KNX
Wiring
Wire Sizes and Lengths for the KNX Modbus Gateway
RP-C Communication Ports