How to switch from voltage device to current device

[cmorrow8]

Hello.  I have an existing LabView program that needs some updating and I'm not quite sure how to do this.  

I have a water tank that I measure the conductivity with using a Hanna Instruments conductivity probe with a 0-5V output.   The problem is the probe broke and Hanna doesn't make them any more.  In fact, I've had to switch to an Okton K=10 probe that has a 0-20mA output which will be read with a NI 9208 DAQ.  

I expected that I would be able to reconfigure the DAQ assist to accomidate my new device, but I can't seem to find how the existing program is aquiring the 0-5V signal, so I don't know how to change it.  

The existing program is receiving the 0-5V signal through a NI-6009 DAQ via the subVI called "Aquire Conductivity Data Loop".  I am attaching that VI here.  Can someone help me figure out how to change from the old conductivity probe to the new probe?

[Bob_Schor]

I'm wondering if an undergraduate EE (or maybe a clever high school student who knows Ohm's Law) can give you a clue ...

Bob Schor

[Mikirius]

Hi,

Please take a look on this information: http://digital.ni.com/public.nsf/allkb/143D1830D99CD40C86257D69007EB302

Its goig to be pretty much the same as with your device.

Regards

[crossrulz]

5V / 20mA = 250 Ohms.  So you will want a 250 Ohm resistor to sink the current and then measure the voltage drop across it.  That will give you a 1:1 equivalent to what you were already measuring and you do not have to change any software.

[RavensFan]

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@BOB Schor wrote:

I'm wondering if an undergraduate EE (or maybe a clever high school student who knows Ohm's Law) can give you a clue ...

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@crossrulz wrote:

5V / 20mA = 250 Ohms.  So you will want a 250 Ohm resistor to sink the current and then measure the voltage drop across it.  That will give you a 1:1 equivalent to what you were already measuring and you do not have to change any software.

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So Crossrulz,

Are you an undergraduate EE, or a clever high school student?

[crossrulz]

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RavensFan wrote:

So Crossrulz,

Are you an undergraduate EE, or a clever high school student?

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Formerly a clever high school student and formerly an undergraduate EE.  Does that count?