YASKAWA G7 Modbus Communication Manual page 12

RS-485 2-Wire Network
RS-485 2-wire networks can be either single or multi-drop networks, with each slave device on the network assigned a unique node address. A
maximum of 31 devices may reside on any network segment before a repeater is required. The maximum segment length is 4000 ft (1200 m).
Set the Termination Resistor S1 switch to ON (slide the switch to the right) on the last device on the network. RS-485 2-wire communication
requires RTS (request to send) control. See parameter H5-07.
Figure 1.5 RS-485 2-Wire Network Connection
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