Concept
Wire Sizes and Lengths for the KNX Modbus Gateway
This section provides recommendations on wire sizes and lengths for the KNX Modbus gateway (RP-C-EXT-KNX).
The recommendations are for guidance only. Other wire sizes and lengths may be used, depending on wiring rules and when appropriate.
The recommended wire sizes in the following table apply to the multiconductor cable connecting the RS-485 Power Adapter to the KNX Modbus gateway screw terminals. The wire sizes do not apply to the Cat 5 UTP cable connecting to the RP controller. For more information, see Convert a BACnet/IP Controller RS-485 Interface .
|
Terminals |
Minimum Cross-sectional Area |
Maximum Cross-sectional Area |
Maximum Cable Length |
|
Power input terminals a |
0.34 mm² (22 AWG) |
2 mm² (14 AWG) |
72 m (236 ft) b |
|
Modbus terminals c |
0.34 mm² (22 AWG) |
2 mm² (14 AWG) |
72 m (236 ft) b |
- Upper 3-position screw terminal block.
- Maximum total length, that is, Cat 5 UTP cable plus multiconductor cable.
- Lower 3-position screw terminal block.
The KNX bus cable should be a KNX certified cable, which typically has a diameter of 0.8 mm (20 AWG), and comply with the length limits defined in the KNX standard, that is, a total length of 1,000 m (3,280 ft). For more information, see the KNX standard and manufacturer's guidelines for shorter maximum lengths between different types of devices.
For more information, see KNX Modbus Gateway Screw Terminals and Connector .
I/O Wiring
Wire Sizes and Lengths
KNX Modbus Gateway Screw Terminals and Connector
Wiring
Convert a BACnet/IP Controller RS-485 Interface