How do I zero out a voltage?

[bradle95]

I am reading a voltage change, but my initial value at when I run my program is not always zero. I am looking for a way to "zero out" my voltage. I tried right clicking on the analog-in vi and selecting "invoke node", changed this to "reinit to dflt", but it doesn't seem to work. Any ideas?

[BJD1613]

could you post an example? Are you trying to zero out the device or the LV code?

[tbob]

If you connect your voltage source to ground, that will "zero" it out very quickly! Just joking!!!
It seems like the vi is remembering the last reading. Is your reading connected to an uninitialized shift register? That will make the vi remember the last reading. If so, just wire in a 0 numeric constant into the shift register. If it is a simple control or indicator, you should check to see if 0 is the default value.

[bradle95]

I am trying to zero out an analog input

[bradle95]

I am not really sure what a shift register is, so I am going to have to say no. What I am doing is reading an LVDT voltage (it shows me the displacement of a part). This part is not going to be exactly at zero displacement every time that I start the program, (it will be giving me a voltage say -0.35Volts to begin). I need to be able to take the analog input that it gives me(-0.35Volts) and make this be my point of of zero deflection (which would read 0Volts).

[tbob]

I am not quite sure what you want to do but it sounds like you want to make your first reading the reference point, and then track any changes on subsequent readings with reference to your first reading. If so, then create an indicator (call it ref), and put it in a case structure. Wire the loop iteration (i) to the case question mark. For case 0 (first time), wire in the LVDT reading into the ref indicator. All other cases will do nothing to change the ref. Now your first reading is stored as a reference, and your next reading can be subtracted from the reference to find the amount of change. Hope this is what you want.

[bradle95]

Perfect!