Reusing nulling properties

[falkpl]

I have a scxi application with many channels (100+) of various sensory including strain gauges using a 1521b and 1317 front end.  I null the sensors when they are unstrained then perform the shunt calibration and use the sensors and all is well.  If I close the program and start over I want to sometimes reuse this previous nulling so that I dont get a rew reference zero point.  What properties (using labview and daqmx 8.7) are set for this nulling so I can save this to file and then rewrite the property nodes if this is desired by the user.  This is a quarter bridge I connection with a 3 wire strain gauge.  I find that the initial bridge voltage and fine potentiometer do not give enough to use these and pick up where I left off.

I did this with a load cell and it workied using the fine, coarse and initial Voltage to get the bridge settings back to the zeroed state.

[HeatherBaker]

Hi Paul,

Are you referring to the process in this knowledge base article?  This second article also indicates the Initial Bridge Voltage property is the way to go about re-using the information.  Can you elaborate on "I find that the initial bridge voltage and fine potentiometer do not give enough to use these and pick up where I left off."? 

[falkpl]

In my application I have many strain gauges, when they are setup using daqmx (not max)  add a strain gauge channes to my task and based on a configuration file that looks up all the parameters about the gauge (gauge factor, lead resistance.....).  Before collecting the data I need to null the bridge (optionally) and then do a shunt calibration.  The Null works fine and so does the shunt calibration and the data looks great.  An additional runs (ie the used terminated the program and restarted)  I want to pickup where I left off, so I do not want to renull the channels but reuse the previous measurments. 

When i nulled the gauges, I saved the channel parameters bridge initial voltage and fine pot setting.  I write these properties back to my task channel but I do not get a correct strain.  Im I missing something. 

I did this for load cells without an issue, saving the initial voltega and the fine and course pot settings.  Just can not get this working with the strain channels.

[HeatherBaker]

Hi Paul,

I have verified with colleagues that it should work with only those settings.  If you are still having issues with this, then please post a small piece of working code where this is not functioning as expected- thanks.