Using the U6 to Measure Force

2 posts / 0 new

Thu, 10/01/2020 - 14:50

jshap

Hi! I am trying to use the Honeywell FSG005WNPB sensor connected to the LabJack U6 to measure force. The following are links relevant to the sensor:

Product page: https://www.mouser.com/ProductDetail/Honeywell/FSG005WNPB?qs=%2Fha2pyFad...

Data sheet: https://www.mouser.com/datasheet/2/187/honeywell-sensing-force-sensors-F...

The sensor has an output span of ~360 mV. I have 6 sensors - the positive leads are connected to AIN0, 2, 4, 6, 8 or 10, and the corresponding negative leads are connected to AIN1, 3, 5, 7, 9, or 11. I am trying to see if a pressure applied to the sensors changes the output voltage measured by the U6 using the LJLogUD. I am using the setting LJ_rgBIP10V. Unfortunately, I am not seeing significant, if any, changes in the voltages measured by the U6 when I apply pressure to the corresponding sensor (the channel with + terminal 0 and - terminal 1 does not display a significant/any change in voltage when I apply pressure to the sensor that is plugged into AIN0 and AIN1).

Could you please advise on which settings are best to measure the specified range of voltages? Is my setup appropriate? Any help would be appreciated, and I would be glad to provide more information if necessary. Thank you!

Thu, 10/01/2020 - 15:38

LabJack Support

Your sensor datasheet is a

Your sensor datasheet is a bit confusing with its specifications, but the sensor is described as ratiometric and appears to be a wheatstone bridge circuit, so that is what I am going to go off of.

I would recommend using the BIP1V range instead of the 10V range. The sensor has a typical sensitivity of 7.2mV/V/N, so that puts your full scale at 7.2mV*ExcVoltage*5N = 36*ExcVoltage. If you have a 10V excitation that puts you at the expected full scale output of 360mV. There is also an offset of around 30mV, so your output at full scale could be around 390mv, well within the +-1V range. If you are using 5V excitation the full scale should be 180mV +30mV = 210mV.

Another good way to look at your output is that you should be seeing a voltage reading of around 7.2*ExcVoltage per N of force applied. Is this around what you are seeing?

I would recommend looking over this forum topic and specifically post #13 here for some additional thoughts:

https://forums.labjack.com/index.php?showtopic=4376