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Hi,

I am trying to wire a 2 wire 0/4-20 mA analog output Flow Meter to a UIA-0204N I/O module, but It doesn't seem I get the correct reading.

The output of the sensor is active. From this I understand that I don't need to supply any DC voltage to the two wires of the sensor, thus one goes to 0V and the other to the input of my card. I also have 0V for the common on my card.

  • Do I also need to include a resistor between the wires of the sensor?

Also, being an active output from the sensor the card needs to act like a current sink.

  • How is that achieved? 

One last thing:

  • how can I easily determine if its 0-20 mA or 4-20 mA if it doesn't clearly specify it on the datasheet of the sensor?

Thanks

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Hi Sanyc

If it is an active transmitter then the transmitter has a separate power input.

Make sure the 0v of the transmitter power supply is linked to 0v of the unitronics input.

you should not put a resistor across the wires.

If you still have trouble please post a sketch of your wiring and the transmitter details.

Regards

Denis

 

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11 hours ago, sgull said:

If it is an active transmitter then the transmitter has a separate power input.

Make sure the 0v of the transmitter power supply is linked to 0v of the unitronics input.

Thanks Denis,

Indeed the transmitter has a separate 230V AC power supply. 

The common on my expansion module is connected to the 0V DC.

Then a wire from the (-) of the transmitter goes to the current input on the 0204n card.

The positive from the transmitter I 've tried both connected to the (+) and the (-) of the 24V DC supply with no success.  

Attached is a photo showing what I did

 

unnamed.jpg

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Hi Sanyc

From the document it says that the output can be passive or active.

If it is passive the output is 4-20ma and you should connect the positive of your 24v supply to the + of the instrument (terminal 26) and the - of the instrument (terminal 27) should go to the input of you analog input card.

If you select active than the - of the transmitter (terminal 27) is wired to the 0 common of the analog input and the + of the instrument (terminal 26) is wired to the input of the analog card. in this case you can select 0-20 or 4-20ma.

Regards

Denis

 

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Thanks everyone, problem solved and I am now reading very good values.

The problem turned out to be in the linearization, I set my Y limits to Y1 = 0 and Y2 = 18000, because I read in the manual that at 1'' the Flow Meter could read up to 18000 kg/h.

Eventually I scrolled the screen inside the Meter and found out that at 20 mA it gives maximum 6000 kg/h. 

So setting the linearization to Y1 = 1 and Y2 = 6000 solved the problem.

Thanks again

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