ABB | E-kit
10 | © 2022 ABB | - 1SDH002203A1002 RS-485 serial communication interface (COM1 port)
Connection among devices
The Modbus RS 485 network is of the “daisy-chain” type (also called in-out) where all the devices in the
network are connected in serial mode. Connection among devices is direct, without ever crossing the cables.
Examples of incorrect connections are illustrated in the next figure
The first setup below is the correct one. Cabling examples are given in the figure below.
The next figure shows examples of incorrect connections.
Maximum distance and
maximum number of devices
The main cable can be up to 700 m in length. This distance does not include branches (which, however, must
be short). Up to 15 devices (besides E-kit) can be connected to a main cable.
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