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Level Sensor Output Signal: 240-30Ω, Is it possible to measure with PXIe 4300?

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Level Sensor Output Signal: 240-30Ω, Is it possible to measure with PXIe 4300?

I'm going to buy NI PXIe 4300 with TB4300C for measuring current from many sensors.

One of the sensors has the level sensor that has 240-30 Ω output. I don't want to buy the DMM module.

Is it possible to use PXIe 4300 with TB4300C or TB4300?

 

Specifications:
Model: 878640
Material: Stainless Steel
Length: 550mm
Protection Rank: IP67
Output Signal: 240-30ohms
Resolution Range: 10-40mm
Operational Temperature: -40°F ~ +185°F (-40℃ ~ +85℃)

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Accepted by topic author JJ@TH
01-15-2019 12:49 AM

Re: Level Sensor Output Signal: 240-30Ω, Is it possible to measure with PXIe 4300?

At least a link to the datasheet of that sensor would be helpful Smiley Wink

What accuracy is needed?

 

IF that sensor resistor can carry ~20mA current, the easy way would be to add a constant 1.5V supply and use your current measurement. The current sensing resistor of the 4300C is 50Ohm (as far as I found the rigth spec) , so sensor and card input in series to a 1.5V source will give you a current range of 20mA (1.5V/(25Ohm+50Ohm) ) to ~5mA (1.5/(250+50)) .

Senorvalues with a little extention Smiley Wink

If you can 'steal' 3.3V- 5V (30mA .. again some buffer)  somewhere in your PXI chassis,  a low drop voltage regulator to 1.5V will do the job. If more accuracy is needed and you are not shure about the stability of your 1.5V source: Measure it Smiley Happy  another current channel and a stable 25Ohm Resistor (4 times a 100Ohm?) and a source supplying 40mA (+buffer) .. voila Smiley Very Happy

 

An other (more common) method: Use 'any' available AC or DC voltage source and a known reference resistor and spend two voltage input channels. Build a voltage divider with the two resistors (known and sensor) and measure the voltage across them.  

If the voltage source is known, only one voltage measurement is needed. 

 

 

Greetings from Germany
Henrik

LV since v3.1

“ground” is a convenient fantasy

'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ'


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Re: Level Sensor Output Signal: 240-30Ω, Is it possible to measure with PXIe 4300?

After a closer look into the 4300C spec .. input impedance is 92 Ohm,

so the supply voltage should be ~2,3 V.  

 

Greetings from Germany
Henrik

LV since v3.1

“ground” is a convenient fantasy

'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ'


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Re: Level Sensor Output Signal: 240-30Ω, Is it possible to measure with PXIe 4300?

Thank you for your suggestion Henrik.

Here are the details in the pdf I got from the website
https://goo.gl/9fPjnL

I don't need high accuracy +- 10 to 20 Ω is fine.

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Re: Level Sensor Output Signal: 240-30Ω, Is it possible to measure with PXIe 4300?

Output .. :WTF is Standard American  240-33 ohms ??  Smiley Very Happy

Migth work as  suggested with a 2.3V supply

 

The very simple version is a 5V supply and  a 150 Ohm , your sensor and the 20mA current input as a serial chain.

Still should show the discrete sensor values ...

The measured current is I= <Your voltage supply voltage> / (92 + <Sensor resistance>+<additional series resistor> )

 

Greetings from Germany
Henrik

LV since v3.1

“ground” is a convenient fantasy

'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ'


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Re: Level Sensor Output Signal: 240-30Ω, Is it possible to measure with PXIe 4300?

I think I will use voltage divider.

Thank you.

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