Jump to content

4-20 mA signal from Hanna transmitter


Recommended Posts


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:



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!


Link to comment
Share on other sites

  • MVP 2023

@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:



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.


  • Like 1
Link to comment
Share on other sites

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?

Link to comment
Share on other sites

  • 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.



Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...