Voltage for sensors connected to AI ports?

knebb

Hi,

I am thinking of using such a device to get the level of water in a tank:
4–20 mA 0–5 V, 0–10 V RS485 Intelligente Liquid Level Transmitter Druck Wandler Wasser Level Sensor Druck

It is supposed to give 4-20mA which I could read on my AI of my M103. Well, I will have to set the AI to get current instead of voltage by setting register 1024 to 1.

My question now: I have to use an external power source for this device. It is designed for 24V. Will this be an issue as the AI usually only can measure up to 10V?

Will it break my Neuron when using 24V as source?

Thanks a lot!

/KNEBB

Martin Kudláček

Hi @knebb,
typically it doesn't pose any problem. But be aware, that when the sensor malfunctions and creates a short circuit, the 24V will apear across the AI terminals. The AI has protection for voltages larger that 15V, which will probably get damage.

Best regards,
Martin

knebb

@Martin-Kudláček :

Thanks. I guess I will take the risk. Mainly because I have no clue how I can prevent any damage :\

Greetings

/KNEBB

Martin Kudláček

@knebb Try running it on lower voltage, or put another resistor in series and do the recalculation in the software.

Martin