I'm working on a round duct system project that involves a damper on the duct outlet to control flow and pressure. ANSI 210-16 requires the damper hole to be symmetrical, so we plan on using sheet metal slides that decrease/increase in area by 10% or so, similar to an iris diaphragm. I need to create a medium that allows Labview and the selected slide to communicate. That way you don't have manually enter which slide you are using every time you change the damper. One of my bosses mentioned using resistors but I have no idea what he is talking about, I am intern who has just dipped his toes.

Q) How could I implement a resistor to tell labview which slide is being used? Should I even use a resistor?

  • 1
    \$\begingroup\$ Your question has too much mechanical information and not enough about the electronics problem. Is the computer permanently connected to several slides? If so, how, and why can't you tell them apart by the connections? Or are you plugging in one at a time? By serial? By USB? By some other hardware? You can edit your question to add these details, look at the bottom left just above this comment. \$\endgroup\$
    – Jack B
    Jun 26 '18 at 18:27
  • \$\begingroup\$ This is just a logic level switch when open a resistor biases to the “1” logic level and the other when closed = 0 \$\endgroup\$ Dec 19 '19 at 5:02
  • \$\begingroup\$ Ask your boss for a better explanation. Ask them to show you. When I was an intern I didn't ask enough questions and didn't do that well. At my first real job I asked every question and it led to a lot of good results (including more senior people questioning why they did things). In fact I'd say you should always ask coworkers first before coming here unless you're being asked to pioneer a new technique that nobody in your office knows. \$\endgroup\$
    – Matt
    May 25 at 2:23

One of my bosses mentioned using resistors but I have no idea what he is talking about

When connected to a voltage source, a resistor causes a voltage drop, which can be measured by an analog input.
I'm pretty sure your Labview environment can read analog inputs through some kind of interface card.
See any tutorial on "voltage divider", for instance here: enter image description here

Vin is a fix reference voltage, Vout is the voltage your Labview environment would have to measure. R1 is also fix.
What makes it work is that R2 has a specific value for a specific slide. What value is used for what slide is up to you.
So, you will get a specific Vout for each slide, which you can measure through your labview interface hardware.
Be careful:
Resistors have tolerances, the connector and the wires may also have significant resistance, aging may be a problem, ...
You will need a voltage margin high enough between all values to avoid misinterpretation.


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