# LabVIEW

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## speedometre

Hello i am new in labview and i am trying to make a speedometre   using gauge and change it direction for an example when i start the program i'd give it a specific number to go to like 5 and it  starts going up till it reachs the number 5 then stops and then by a press of a button  it will start going down ,well  i'v been trying searching youtube  and reading about some examples in here but i still dont know how to make it if anyone can help me, at least on where to start from.

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## Re: speedometre

What does a speedometer measure?  What do you call the control (on a car) that makes the speedometer go up?

[Since I don't know your native language, only know it is not US English by your spelling, I'm going to provide the answers to the above questions.  The speedometer measures "speed", the magnitude of the vector called "velocity".  The control that changes the speed is an "accelerometer" (sometimes called the "gas pedal"), and calls to mind "acceleration", the (time-)derivative of velocity.

Do you know how to relate velocity and acceleration?  If you know the velocity now and the acceleration now, what can you tell me about the velocity one second from now?

If I assume acceleration is held constant, how will velocity change with time?

Did you know that time is an intrinsic "thing" in LabVIEW?  There's an entire Palette devoted to it.

How would you go about expressing a quantity that changes in a "regular" (undefined, but maybe you can think of it as "the same way every time")?  Oops, there's that word "time", again.

Write some LabVIEW code.  Sprinkle it with indicators so you can see how the data "in the wires"   Can you relate any of this to your task?

Bob Schor

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## Re: speedometre

@DestroF wrote:

Hello i am new in labview and i am trying to make a speedometre   using gauge and change it direction for an example when i start the program i'd give it a specific number to go to like 5 and it  starts going up till it reachs the number 5 then stops and then by a press of a button  it will start going down ,well  i'v been trying searching youtube  and reading about some examples in here but i still dont know how to make it if anyone can help me, at least on where to start from.

So this is just a simple simulation that takes a while to go to a new value. How realistic does it have to simulate the acceleration of a car? What are the input parameters that define the behavior vs. time?

A very primitive example would be an exponential filter, so start with this example, then change the math to something more realistic. Change the chart to a gauge or dial, etc.

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