I try to connect the DT800 with a pressure sensor which has 2 wires (+) and (-) , excitation 10-28Vdc, and output: 4-20mA (current loop).

I set differential in Delogger, and plug in 2 wires to + and -accordingly. It gives me a very tiny value (-0.1543) as the output. do you know what goes wrong? to make the value fall between 4-20mA.

Thank you very much
Paul

Good morning Paul,

Do you have a shunt resistor across the + and - terminals?
You should also connect the - to the AC terminal.

Cheers,
Roger

Roger,

Can I use a lab use resistor(with the color code on it) as a shunt resistor? Or I have to use a specific one?

Thank you very much
Paul

Good morning Paul,

Because Voltage = Current * Resistance, if we have a known resistor and the dataTaker measures the current we can calculate the current.

The maximum current flow for your device is 20 mA so a 100 Ohm resistor will have a 0.02 A * 100 Ohms = 2 VDC voltage drop across the resistor.

The more accurate the resistor the more accurate your measurements. E.g. If you choose a resistor that is +/- 5% then your readings can have an offset of up to that tolerance.

You can purchase Shunt resistors from any supplier of electronic components. If you think the resistors in your lab will be sufficient accuracy, temperature stability and have a good power rating then yes it will work.

Cheers,
Roger