Rs-485 Half-Duplex Wiring Example - Campbell SDM-SIO1A Instruction Manual

As with all RS-485 configurations, the use of termination resistors
NOTE
is optional. They tend not to be required with shorter cable runs
and with modern slew-rate-limited driver technology (as used in
the SDM-SIO1A).

6.2.1.3 RS-485 Half-Duplex Wiring Example

This shows how to connect a single device, but RS-485 half-duplex networks
are the most common multi-drop configuration. If wiring for multiple devices,
make the three wire connections in parallel, similar to that shown in the full-
duplex multi-drop example.
As with all RS-485 configurations, the use of termination resistors
NOTE
is optional. They tend not to be required with shorter cable runs
and with modern slew-rate-limited driver technology (as used in
the SDM-SIO1A).
SDM-SIO1A and SDM-SIO4A Serial Input/Output Modules
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