RS-485 is long standing interface that has proliferated industrial based communication applications for almost three decades. Championed for its simplicity and its technical benefits, namely a differential wire communication interface with relatively high data rates and a large common mode range which enables accurate communication across long busses in multi-point networks, has made RS-485 the most used wired communication standard in industrial applications. With a relatively minimal set of requirements, RS-485 systems have much variability and each system, as well as RS-485 transceiver, needs to be carefully designed to best provide the specific application needs. This leads to considerable design effort for each RS-485 system and with many RS-485 transceivers being designed for specific niches within the overarching RS-485 standard which can further compound the complexity of the design and qualification processes. However, with TI’s new Flexible RS-485 Transceivers, the THVD1424 and the THVD1454, one IC can now cover a wide array of RS-485 based applications which designers can leverage into multiple systems – removing the need to select and qualify multiple devices for each new design. This application report briefly explain: the RS-485 use case domain to see the vast differences possible between RS-485 systems; a quick look at the traditional design flow of RS-485; finally, an overview of how Flexible RS-485 overcomes problems that exist in the traditional RS-485 system design.
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The RS-485 standard defines a differential, bi-directional, and multipoint wired communication interface. The standard is published jointly by the Telecommunications Industry Association (TIA) and the Electronic Industries Alliance (EIA). It defines the electrical characteristics of the interface circuits, but does not define cabling, connectors, nor data protocol(s) used.