Window Motor Problem?

[Kevin Sevcik]

Originally Posted by cdizzle

Wait, so if I set my motor speed to 0 when false in the case block for button 3, will it affect the motor when the button 4 case block is true?

Originally Posted by nicholsjj

No it should just affect the output from case three. My next question is are you sending both button outputs into the same motor set output vi. This might be where Kevin's statement about overriding can occur if you use two different vi's.

If you have two completely separate case blocks for button 3 and 4, then yes, the false case in the button 3 block will affect button 4 even if button 4 is true. See my attached snippet. The top two show the cases in the case blocks. The bottom shows what will run when button 3 is false and button 4 is true. Both of those case blocks will run, which means you're trying to set the motor speed to 0 and set the motor speed to 0.9 at the same time. The results of trying to set the motor to two different speeds simultaneously are not particularly predictable.

Cecil's suggestion of putting the motor set block outside of the cases is also a good one. Then you know that you only have one motor set and it's only going to run once. Then you just have to figure out how to send it the appropriate value. It makes it pretty obvious if your value selection method isn't valid because you'll end up trying to wire two thing to the same input, which labview will complain about.

[cdizzle]

I got it working! Thanks for your help guys! I think something was overriding the reverse command, but I couldn't figure out what it was, so I just wired it to one SetMotorSpeed like you guys said to.

[Cecil]

Originally Posted by Kevin Sevcik

What I like to do for programming two buttons to turn a motor is to pick a dominant case. That means that you pick one of the buttons that "wins" if both buttons are pressed. Then you can pretty easily use two Select blocks to set the motor speed. See my attached code snippet, in which button 3 "wins" and gets final say in the motor speed.

What I've always done is just put the numbers in the case statements, with the Set VI outside the case. The true cases have the values to set the motor to, and the false cases both have 0 in it. Just to the right of the case, I put an addition operator in. That way, if one button is pressed, it adds 0, not affecting the output. 0+0 = 0, x+0 = x, and x+y=0. (Of course, this only works when both positive and negative values are the same...)

Edit: I also use the Select statement for the values, not just cases. Keep forgetting I usually put global sets in there too.