Auto Zero does not zero in Signal Express.

[OKors]

This is frustrating to have an Auto Zero option in SigEx and have it do nothing. Regardless if I set it to NONE or ONCE, it simply does nothing to the offset found in my transducer- be it a load cell, stick pot, or string pot.

We do a lot of force/deflection tests here and it's important that after all specimen bolt ups are done we zero out any load and displacement offsets.

The only way I can zero any offest is to add a Y-intercept to the Linear Scale. Then if the y-intercept is too great I get errors about Min/Max values not being valid, so then I have to go through channel by channel and manually adjust my min/max inputs till the errors clear.

Example; I'm currently doing a slip test with bolted joint components, I'm measuring slip from 15 points along various bolt locations with Duncan stick pots (1.5" travel). I set my Min/Max input as 0 and 1.5, crate a linear scale with a slope of .15 @ 10Vex.

However I want the ZERO of my stick pot to be someplace mid stroke so I mount them to the surface accordingly.

Now I have to run a 'pretend' data plot, monitor the offsets and manually enter this as my intercept of each channel. Now my Min/Max ranges are not longer valid because I'm at mid-stroke, so every channel gives me errors. I have to then manually re-adjust my min/max ranges till they clear.

10 channels later, and over 45 minutes to set up what should be a "slam-dunk" test.

Auto Zero anyone???

[Scott-M]

The Auto Zero in SignalExpress shorts the input channel to ground and then subtracts the obtained measurement from all subsequent samples. So Auto Zero is not going to zero your signal, its going to zero out any offset in your system (not out side it) and then reattach your signal, this is why you were only seeing small changes in your reading.

As far as I know you are going to have to adjust the range and Y intercepts for each new test you run. Sorry for the confusion, let me know if you have any further questions.

Thanks
Scott M.

[OKors]

Hmm... that's discouraging to say the least. Autozeroing a transducer offset is a pretty common function in almost every piece of DAQ hardware I've used; Somat eDAQ, HBM, AVL, IOtech, MTS FlexTest, even the old Megadac.

Will there ever be an option for this?

To zero out 10-20 channels of displacement transducers manually by entering a y-intercept in the scale is a complete time-suck.