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LabJack U3 or other model recommendation

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#1 madmax81

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Posted 01 October 2014 - 05:05 PM



I'd like to connect up to 8 sensors (Broadband Lambda sensor, RPM Sensor, Temperature sensor...) to LabJack and write my own software which does realtime monitoring of the sensor data. All sensors are monitored simultaneously. Is the U3 model sufficient for that purpose or would you recommend another model?


Thank's in advance!



#2 LabJack Support

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Posted 02 October 2014 - 07:43 AM

Most new applications use a device from the U3, U6, or T7 family.


How fast do you need to sample the 8 sensors?


What sort of output do you get from your "broadband lambda" sensor?  Variable voltage output?  What is the max & min voltage?


Please provide a link to technical details for your RPM sensor so we can see what kind of output signal it provides.


What type of temperature sensor are you using and what range of output do you expect from it?



#3 madmax81

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Posted 02 October 2014 - 10:52 AM

Thank you for your answer!


I have to admit that this is my first project where electronic is involved. Therefore I'm not sure about the sample rates I will finally need. The idea is to built a motorcycle dynamometer. The RPM sensor measures the drum which is running with up to 5000 rpm. The LabJack interface must be able to process the sensordata fast enough for a accurate and fast responding realtime monitoring. I'm sure that I can trust in your experience.


Below are links to the technical datasheets of the sensortypes I plan to use.




Lambda sensor




RPM sensor






Temperature sensor



#4 LabJack Support

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Posted 02 October 2014 - 03:56 PM

The lambda sensor is an unknown for us.  It looks like perhaps you give it 7.5V excitation and it then provides a +/-2mA signal, but other language on the datasheet makes me think it is not that simple, including:


"This lambda sensor operates only in combination with a special LSU-IC"


... which makes it sound like the sensor is very special and requires a special IC to excite it and measure from it.  If you do research and get to the point where you can read the sensor with a DMM, then we can translate that to how to read with a LabJack.



For the first rpm sensor, you would have to provide a 12V supply and then it provides 7mA when low and 14mA when high.  You would need a load resistor, and then also a comparator IC to get a nice voltage pulse signal.


The second rpm sensor looks better.  You can just give it 5V from the LabJack and it outputs a voltage pulse that will connect directly to a digital input.


Once you have an RPM pulse train, you will use a counter or timer to count or time the pulses in hardware, so you do not have to read from the LabJack fast.



The sensor you linked has an I2C output.  The LabJack can talk I2C, but I would consider it an advanced topic so if you are not comfortable with I2C I suggest a different sensor.



#5 madmax81

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Posted 03 October 2014 - 01:37 AM

I found a converter for the lambda sensor. The converter controls all the functions of the sensor and can deliver the data analog and digital. I hope we can get the lambda sensor working with LabJack using this converter.


Here the link to the datasheet of the converter.


http://www.breitband...de V4.0 12V.pdf



With the temperature sensor I'm flexible so it's no problem to choose another one.


So do you think that the U3 Labjack is ok for my plan?

#6 LabJack Support

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Posted 03 October 2014 - 08:46 AM

The signal conditioner for the lambda sensor looks good.


If you use a silicon type sensor you should be good with the U3.  If you use something else let us know what you are looking at.

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