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BEST WAY TO READ 0-10VDC SIGNAL


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5 replies to this topic

#1 alanglynsmith

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Posted 02 September 2013 - 04:48 AM

Hi just wondering if anyone has any ideas about the best way to wire up a 0-10vdc signal (from a pressure sensor) to a U3HV?

 

I suppose we should use the LJ_ioGET_AIN_DIFF command

 

But not sure from the LabJack manual how to wire it up and to which ports?

 

Thanks

 

 

 



#2 LabJack Support

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Posted 03 September 2013 - 11:00 AM

Please provide a link to technical specs for the pressure sensor.

 

Will you power it using VS from the U3, or some external supply?

 

What are your plans for software?



#3 S Elliott

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Posted 24 September 2013 - 11:00 PM

I'm also trying to do this, we've had a system running which records 2 x 0-10V pressure sensors simultaneously, and now have the requirement to add 2 flow meters to the recording as well. We currently power the pressure sensors from a separate 24VDC power supply, and run the 0-10V outputs to the SGND and AIN0/1 inputs on the Labjack. Now I want to add 2 flow meters as well which are also 0-10V output and powered from the same 24VDC power supply as the pressure sensors. My question is, can I just connect all of the 0V outputs together and into 1 SGND, or would they all need a separate GND on the Labjack?

 

I tried to attach a schematic to show what I mean, but I can't work out how to do it?

 

Thanks



#4 LabJack Support

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Posted 25 September 2013 - 08:28 AM

I gather on all 4 sensors you get a single output connection which is referred to power supply negative?  Or if there is a - output connection, it is the same as power supply negative?

 

The best way is to run a single wire from negative on the 24VDC supply to SGND on the U3.

 

To avoid errors due to the resistance of SGND, you might need to use GND instead.  Tell us more about the 24VDC supply.  Is it an AC/DC supply?  Does it connect to anything besides these 4 sensors?  Do you think the negative of the supply is connected to earth/chassis/wall ground?



#5 S Elliott

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Posted 25 September 2013 - 03:44 PM

I gather on all 4 sensors you get a single output connection which is referred to power supply negative?  Or if there is a - output connection, it is the same as power supply negative?
 
The best way is to run a single wire from negative on the 24VDC supply to SGND on the U3.
 
To avoid errors due to the resistance of SGND, you might need to use GND instead.  Tell us more about the 24VDC supply.  Is it an AC/DC supply?  Does it connect to anything besides these 4 sensors?  Do you think the negative of the supply is connected to earth/chassis/wall ground?

Ok so I've just checked, the 0V output from each of the sensors is connected to the 0V of the 24VDC power supply, therefore I only need to connect the +10V output from the sensors to the Labjack (I assume AIN0-3 are the best inputs to use?) And then I will also connect the 0VDC from the power supply to either the SGND or GND of the Labjack.

 

The 24VDC power supply only powers the sensors, and will be ran from through a transformer which is connected to the same 230V AC power supply as the computer that we are using to power the Labjack.

 

Just out of interest what is the difference between SGND and GND on the Labjack? I notice that there are 2 SGND connections, and 5 GND? Are all GND's connected together internally, or are they there to provide separate GND's for signals etc?



#6 LabJack Support

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Posted 26 September 2013 - 02:03 PM

On the U3-HV, AIN0-AIN3 are the +/-10V inputs, so you want to use those if your signals go up to 10 volts.

 

Based on the information you have provided, are think you are fine to use GND, so make the one connection from power supply 0V to GND on the U3.

 

All GND terminals are the same.  GND is the main ground on the entire PCB, is the reference for single-ended analog inputs, and is the same as USB ground.

 

SGND has a series thermal fuse and then connects to GND.

 

http://labjack.com/s...users-guide/2.3

 

http://labjack.com/s...s-guide/2.6.3.4




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