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Koncept

Koncept


Produkter: RP-C, RP-C-EXT-KNX
Funktionaliteter: Maskinvara
Produktversion: 3.2, 3.3
2023-02-26

RP-C Modbus

The RP controller Modbus RTU (RS-485) subnetwork allows standard Modbus devices and the KNX Modbus gateway (RP-C-EXT-KNX) to be connected to the controller.

For the KNX Modbus gateway, the RP-C controller provides both 24 VDC power supply and communications through the Modbus network connection.

For standard Modbus devices, a separate power supply unit (PSU) is needed to power the Modbus devices on the network.

The Modbus RTU protocol is used for the communication. The RP-C controller acts the Modbus master and the connected devices act as slaves.

The Modbus communication parameters can be freely configured regardless of which RS-485 port on the RP-C controller that is used for the Modbus network. Mer information finns i RP-C Communication Ports .

The maximum total length of the Modbus (RS-485) network is 72 m (236 ft). The Modbus network uses a Cat 5 (or higher) unshielded, straight-through wired cable with eight conductors (four twisted pairs) and RJ45 connectors. The wire size (cross-sectional area) should be 22 to 26 AWG (0.34 to 0.14 mm²). When the RP-C controller is installed in a space that handles conditioned air or return air, the Modbus network cables and IP network cables frequently must be plenum-rated to meet applicable building codes. Mer information finns i Wiring .

Obs!

LOSS OF COMMUNICATION

  • Ensure that the total length of the Modbus network does not exceed 72 m (236 ft).

  • Use a Cat 5 or higher unshielded twisted pair cable with eight conductors (four twisted pairs), a cross-sectional area of 22 to 26 AWG (0.34 to 0.14 mm 2 ), and a rating that meets the requirements of the target environment.

Failure to follow these instructions can result in loss of communication.

You need to configure which RS-485 (RJ45) port on the RP-C controller to use for the Modbus network. You can configure to use either the Sensor Bus port (RS-485 Com A) or Room Bus port (RS-485 Com B). Mer information finns i RP-C Communication Ports .

 
action_zoom_plus_stroke Location of the Sensor Bus port (RS-485 Com A) and Room Bus port (RS-485 Com B) on the RP-C controllers
Figur: Location of the Sensor Bus port (RS-485 Com A) and Room Bus port (RS-485 Com B) on the RP-C controllers

The maximum number of Modbus devices that can be connected to an RP-C controller depends on the type of Modbus device and the number of Modbus registers.

The maximum number of Modbus registers that can be connected to and managed by an RP-C controller depends on the communication capacity of the controller's Modbus network.

The RP-C Modbus network supports up to 10 connected Modbus devices with the following restrictions:

  • Maximum of one KNX Modbus gateway (RP-C-EXT-KNX)

  • Maximum of 250 Modbus registers per network

The RP controller Modbus network does not support 64-bit Modbus registers.

 
action_zoom_plus_stroke Examples with one KNX Modbus gateway and several standard Modbus devices connected to an RP-C controller in a daisy-chain configuration
Figur: Examples with one KNX Modbus gateway and several standard Modbus devices connected to an RP-C controller in a daisy-chain configuration

The KNX Modbus gateway has the default Modbus address 1. The address can be configured through the ETS. Mer information finns i Configuring the Modbus Device Settings in the KNX Modbus Gateway .

Se även

  • Hardware Overview
  • RP-Cs
  • Wiring
  • RP-C Communication Ports
  • RP-C
  • KNX Modbus Gateway RP-C-EXT-KNX
  • RP-C-EXT-KNX
  • Configuring the Modbus Device Settings in the KNX Modbus Gateway
  • ETS Database for the KNX Modbus Gateway