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The RS-485 Unit Load and Maximum Number of Bus Connections


The TIA/EIA-485 (RS-485) standard defines a Unit Load and confines bus configurations to 32. This report explains the Unit-Load concept and how it relates to the maximum number of bus connections. Fractional Unit-Load devices, such at the 1/8th Unit-Load SN65HVD21 and SN65HVD06, allow up to 256 devices on a single bus segment.