Fieldbus or analogue: how to connect a sensor
4–20 mA isn't obsolete, and knowing when it's the right answer saves money.
A 4–20 mA loop carries one value, is immune to most electrical noise, and every PLC in the world can read it. For a single measurement feeding a single control loop it is still the right engineering choice.
When to move to fieldbus
Fieldbus earns its cost when you need more than one value per sensor, diagnostics, or synchronisation between sensors. Thickness calculated from two heads, or profile data, can’t travel over an analogue loop at all.
