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+/- 15 VDC analog Input Possiblities


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#1 VHD

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Posted 16 January 2014 - 07:27 PM

Greetings Labjack Community:

 

I have a pressure transducer that has a +/- 15 VDC analog output.  Is there a configuration or a third party device that can be connected to a U6/U9 or T7 that allows me to read those values?

 

Thanks.

 

VHD



#2 LabJack Support

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Posted 17 January 2014 - 10:11 AM

To measure +/-15V with the U6, UE9, or T7, you could get an LJTick-Divider with the custom BIP25V option:

 

http://labjack.com/s...vider/datasheet

 

 

+/-15V is a strange output range.  Can you provide a link to technical specs?

 

Are you expecting to use the full range?  For example, say you need to measure to 100psi.  If you buy the 200psi sensor, then 100psi will be 7.5 volts.



#3 VHD

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Posted 21 January 2014 - 08:25 AM

I was mistaken, the two pins for power are +/-15 V while the anolog out is 0-10 volts.  With that being said is it possible that there may be a spike in voltage temperarly where the analog out in some instances is 0-13?

 

I also wanted to power my barometer using the labjack and a power supply, is that possible or do I need:

 

http://labjack.com/s...-1040/datasheet

 

Thanks.



#4 LabJack Support

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Posted 21 January 2014 - 11:37 AM

If they say the analog signal is 0-10V, I would expect it to not go much over 10 volts.  If it does spike to 13 volts that will not cause damage.

 

Can you provide a link to technical specs for your barometer?  What is the supply range?  How much current?

 

Perhaps the following is what you want:

 

http://www.digikey.c...-2447-ND/920407

 

That is the TDK CC1R5-0512DF-E, which takes a 5V input and produces dual +/-12-15V outputs.



#5 VHD

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Posted 21 January 2014 - 01:07 PM

The technical specs is:

 

http://www.mksinst.c...s/UR/627Dds.pdf

 

MKS Model 627 Absolute Capacitance Manometer, Heated to 45 °C., with ±15 VDC power input and 0 to +10 VDC output and RoHs compliant. ±15 VDC ±5% @ 0.25 Amps (max.)

This instrument will have the following configuration:

Range: 20 Torr

Fitting:  8 VCR female

Accuracy: ± 0.12% of reading

Options: none

Connector: 15-pin Type”D” w/thread lock

 

Ideally I'd like to use, http://labjack.com/s...-1040/datasheet.  Do I still need an external power supply?



#6 LabJack Support

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Posted 21 January 2014 - 01:14 PM

To convert 5 volts to +/-15 volts, you are doing a 6x increase so the 5 volt current will be at least 6 times the +/-15V current.  Your sensor says +/-15V @0.25A, so that means it would draw 1.5A from 5 volts, which is way too much.  You will need to provide an external supply.



#7 VHD

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Posted 21 January 2014 - 01:33 PM

So if I want to connect this to a T7 or U6, I should be able to connect this to one of  the AIO pins and provide an external power supply for the manometer, is this correct?  Or do you recommend a simpler or more elegant solution?



#8 LabJack Support

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Posted 23 January 2014 - 09:55 AM

Yes you can connect the signal directly to the U6 or T7, and with this particular sensor you will need to provide a power supply for the sensor.  To avoid the external power supply you need to find a sensor that does not use so much current, and preferably that runs off 5 volts.

 

I am not familiar with this particular type of "manometer" sensor.  If you can use a general pressure sensor, consider looking at options from Omega or the "integrated" sensors from Freescale:

 

http://www.omega.com...ransducers.html

 

http://www.freescale...=01126990368716




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