Endress+Hauser RB223 Mode D'emploi page 28

Input - Connecting transmitter
No additional components are needed to supply passive transmitters. If
energy-rich transients are anticipated in long signal lines, we
recommend the use of overvoltage protection e.g. HAW562/562Z.
Output - Connecting evaluation unit
If the communication resistor is looped into the current loop, the drop
in voltage must be taken into account.
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