Maximum number of node can be connected through one RS485 network
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128
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64
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32
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16
The RS485 standard specifies a maximum of 32 unit loads on a single network segment without repeaters. While modern transceivers with fractional unit loads can extend this to 128 or more devices, the classic RS485 specification defines 32 as the standard limit. Options A and B (128, 64) require special low-unit-load transceivers, and D (16) is below the standard capacity.
The RS-485 electrical standard supports up to 32 unit loads (nodes) on a single bus segment without repeaters, due to its specified driver output and receiver input impedance limits. Higher counts like 64 or 128 require special low-impedance transceivers and aren't part of the basic standard, and 16 understates the actual limit.