Sensor output type

Hi All

Looking to connect the output of a omega infrared sensor to an arduino so that the arduino can be used to control the temperature of the object which the infrared sensor is..sensing! (Link for sensor here: Compact fixed infrared temperature sensor and Transmitter).

The accurate temperature range required will be between 20 and 400 degrees Celsius (possibly higher) so will probably choose the sensor which has the range of -18 to 538 degrees celcius.

My question is basically what output would be best for sending to the arduino in terms of maintaining the resolution and accuracy of the sensors measurements.

The outputs available on this sensor are : Outputs:
-MA: 4 to 20 mA
-V1: 0 to 5 Vdc
-V2: 0 to 10 Vdc
-K: K thermocouple
-MVF: 10 mV/°F
-MVC: 10 mV/°C

I spoke to an omega salesman and although he did not have much knowledge of connecting these sensors to an arudino (as usually these sensors are purchased with the control unit also) he did recommend the 4-20mA output, was just hoping for a second opinion on this?

If I have missed any points which might be handy to know please let me know!

Thanks in advance!

0 - 5V Would be easiest to connect to Arduino analog input, ADC result will be 0 - 1023 (10 bit).
Resolution will be about 0.543 C per step.

A current output is useful when there's a lot of EMI flying around as current, but voltage output is
more convenient otherwise.

Thank you both for your replies! Really helps!

One more quick question I have is would be be more feasible to chose a 4-20mA signal or 0-50mV signal?

The reason I ask this is because there is a sensor available which is significantly cheaper than the first one that I posted (link: http://www.omega.co.uk/pptst/OS210-150-300-800.html) however it only offers these 2 outputs (as well as thermocouple outputs).

Sorry to be repetitive in regards to my question but just want to make sure I chose the sensor with the most suitable output for the Arduino!

Thanks again.

new_to_this:
One more quick question I have is would be be more feasible to chose a 4-20mA signal or 0-50mV signal?

In order to use the 4-20mA signal, all you need to do is connect a current sinking resistor between the signal and common GND. You can then read it as an analog voltage signal. The 0-50mV signal will probably require you to use the Aref pin to get the sort of resolution you need.

I'd go with the 4-20mA output.

Hi Guys

Sorry for late reply, but thanks for the advice! Got the sensor connected and managed to take some readings using the arduino.

Just wanted to check, if I have my arduino connected to my laptop and I am sending a 4-20mA signal to analog pin of the arduino from the sensor, is this safe or is there any risk of damage to the arduino and laptop?

The power supply for the sensor required is 24V but will manage on slightly lower values of voltage too.

Thanks again.

You don't send current to an analog pin, you apply a voltage to the analog pin. It's the voltage that you care about, nothing else.

You can send the current through a 220 ohm resistor to ground, and the voltage across that will
be 0.88V to 4.40V for the 4…20mA range. The Arduino pin can just snoop that voltage.

Connect a 20mA current source directly to an Arduino analog pin will fry its protection diode.