SLLA595A October   2022  – January 2023 THVD1424

 

  1.   Abstract
  2.   Trademarks
  3. 1Typical RS-485 Networks and the Need for Termination
  4. 2Network Length, Data Rate, and Stubs
  5. 3Discrete Solution for Switchable Termination and Duplex Switching
  6. 4Discrete Solution for Duplex Switching
  7. 5THVD1424 Flexible RS-485
  8. 6Application Diagrams with THVD1424
  9. 7Experimental Results from Four Node Testing of THVD1424
  10. 8Conclusion
  11. 9Revision History

Abstract

RS-485 has been the most used wired communications interface in industrial applications for more than two decades now. Balanced differential signaling of RS-485 allows for rejection of common mode noise and facilitates communications over long distances in noisy industrial environments. RS-485 is a common communications port in most industrial applications such as factory automation, protection relay, solar inverter, energy meter, motor drives and building automation.

Based on the needs of the end-equipment, RS-485 networks have to be designed for different bus supply, logic interface supply voltage, network length and throughput. As a result, customers have to select, test and qualify multiple RS-485 transceivers available in the market to meet unique application requirements. Additionally, system designers develop different printed circuit boards (PCBs) for end nodes and middle nodes in a network because the end nodes usually require termination resistor to improve signal quality. This process consumes significant design bandwidth and resources, increasing the system design time and cost and delaying the time to market.

THVD1424 provides the flexibility to system designers to use the same device at any node location (end-node and middle-node) in any network, two wire (half duplex) or four wire (full duplex), slow or fast. Thus, by using THVD1424, a common PCB can be designed and configured via software for various application needs, saving considerable development time and effort.