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4-20 mA signal from Hanna transmitter


Jungletron

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Hi,

I was hoping to use URA-0800O (AI08O)  or URA-0400O (AI04O) to get  the 4-20 mA signals from Hanna transmitter (EC and pH).

From the Hanna transmitter manual

HI 98143-20  is 4-20 mA passive

and HI 98143-22 is 4-20 mA active

and in the last page:

image.thumb.png.d51f0199948df9ad022a748bc4f17071.png

Questions:

1 - Is the HI 98143-22 compatible with Unitronics sink type analog inputs ? (and the HI 98143-20 not compatible ? )

2 - Is the 2 Input Common(AGND) to 4 Input Common(AGND) difference between the URA-0800O (AI08O) and URA-0400O (AI04O) relevant for this choice?

Already found info in the forum about double sinking and I really do not want to mess this ...

Thanks for any help in advance!

JT

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@Isakovic-  Because the -20 is not a two-wire transmitter.  It's a powered device with two outputs - pH and conductivity.  You have to zoom into the above diagram to see the rest of the story:

image.png.2653d2e06a0b2b5f6ae366b0e2c75e26.png

 

The power supply negative is connected to the loop negatives.  This is a sinking loop output and absolutely ridiculous.  In your diagram, take the negative of your 24V power supply and connect it to the 0 on the HI 98143-20.  You'll immediately see the problem.

If we had isolated analog inputs this could be made to work.  But, alas, we do not.

 

Joe T.

 

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Oh I see it now!

If the PLC and Hama are powered from the same supply both CH1 and GND on the PLC module will effectively be on the ground potential.

Now I suspect AI08O also has GND and negative power terminal connected, so switching terminal places would not work. But will it work if separate power supply is used only to power Hama (not referenced to the ground), and other supply is used for current loop and PLC?

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  • 7 months later...

Hi...In the event that the simple data sources are secluded, simply wire in arrangement.On the off chance that they are not secluded, wire to one as 4-20 mA, wire to the next as Voltage in equal.Wire to one PLC as a 4-20 mA contribution, from that PLC wire a simple Output to a contribution on the other.Before PLCs became basic collectors were wired in arrangement constantlyTransmitter, Controller, Chart-recorder, Alarm unit and so forth

Wiring in arrangement you simply must be cautious you don't run out of force supply Voltage, study the transmitter manual.

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