RTD-DSX: Our Modbus gateway

Description

The RTD-DSX gateway is a Modbus monitoring and control interface for our products that support the D-Bus and Modbus protocols. The RTD-DSX gateway allows the connection of a Modbus Master to a network of devices without interfering with inter-device D-Bus communications (e.g. RTD-10 Duty/Standby mode, RTD-20 Retail mode).


The gateway allows access to the Modbus registers on all attached D-Bus network devices through a series of mapped Modbus addresses. Multiple RTD-DSX - proxies can be networked together to map a large number of D-Bus network devices onto a Modbus network.

 

Typical use

  • Allows use of RS232 standard (uses 6/6 RJ11 port), as well as of RS485 (supported by our other products) for communication with to the external BMS system. 
    • The RTD-DSX has two ports acting as 'Port 1' for external communication. One of these supports the RS232 standard and the orther supports the RS485 standard. Only one may be used at any time.
    • 'Port 2' supports only the RS485 and is for the local ('internal') communication, e.g. for communication with other RTD interfaces.
    • Note that ports 'Port 1' and 'Port 2' cannot be inverted, it is not possible to use 'Port 1' for local ('internal') communication.
    • The protocol used is Modbus. For further information, please see the article Using Modbus with our interfaces. The Modbus commands are those used for the connected devices.
    • For information on the how many RTD-DSX interfaces can be networked to an external master, as well as supported network topology, please see the attached installation instructions.
  • Some of our products operate in modes in which these products are the network master (e.g. RTD-10 in Duty/Standby mode, RTD-20 in Retail mode). In such cases a Modbus gateway is required to gain access to the Modbus registers. The RTD-DSX allows access to these stand-alone networks.
  • Large networks:
    • Several of these stand-alone networks can be connected to the main network.
    • Address mapping: Some products only offer a limited address range. Using the RTD-DSX this can be overcome.

Please see the attached installation instructions for detailed information.