You may need to be careful here — it sounds as if this terminal may possibly be marked / identified as 'SENSOR IN', and if so, you really need to ask your customer if they intend to localize the markings on the equipment istelf; if not, you might need to retain the source text, and just give a translation in brackets afterwards, for example.
In most situations like this, 'sensor in' would be shorthand for 'input from the sensor', and refer to the input (to the equipment) coming from the sensor — just as you might have 'audio in' on an amplifier, say.