LabVIEW
Stepper motor oscilates in reverse using Arduino
@Carlr wrote:
apok,
Thanks for your suggestion.
I an not an expert on labview or with control systems, and so am trying to keep it simple. Currently I have code and hardware that nearly works and I'd rather try and resolve my current issues and not have to learn how a H-bridge works and how to implement it. Obviously, if there is some reason why my current implementation is inappropriate and will not work then I will consider other options, but I would like to understand why the current implementation does not work.
My testing shows that the motor will turn in reverse if supplied a negative input value (from control) its just that it oscillates when supplied on from a variable. This leads me to think that my hardware is OK, but I have an error in the labview code. Please let me know if you think that this is an incorrect assumption.
H-bridge driver is a hardware item, not LabVIEW - other poster is talking about your physical connection and related circuitry. You don't need to do that, your hardware is fine. Your problem is the logic you have implemented (including the portion to the LEFT of the section of code you've shown in your image. You simply need to update it so that negative values can be passed in the wire. See attached image, items circled in RED will prevent any negative values and replace them with a zero. You just need to adjust that logic and what you have just outside of it.
-DP
(And by the way, you have changed the logic from what I had suggested earlier - by doing that you are now constantly writing to the stepper motors except for when it has to write a Zero. instead of only writing when you change input value. Much better/easier way of doing that is in the second image. I don't have all your subVI so one of the block is missing - shown with a "?" as its icon.)
Here's how you could improve your code logic (on FALSE side you'd simply pass the wire values):
@apok wrote:
@BTC_Admin wrote:
H-bridge driver is a hardware item, not LabVIEW - other poster is talking about your physical connection and related circuitry. You don't need to do that, your hardware is fine...how do you know his hardware connection is fine? do you know what it is? are you going on a hunch? we need Jeff's 8 ball here....(just kiddn jeff)
how do you know he is not connected to lemon or bananna interface? sheeeesh!
and he still did not answer if he has a neg PWM signal...remember: software/hardware is half the battle my friend (are you a computer science major?)
Did you bother reading his entire post?
1. He mentioned that his "input signal" is an integer in the range -250 to +250... Hence simply an I16 number, he is NOT speaking of any hardware input signal.
2. He mentions "If i remove the signal input and replace it with a control value the motor turns correctly in reverse, i.e remove the line connecting Base Input to the stepper driver icon and replace it with a control inside the case structure. This suggests to me that it is not a hardware problem. The true/false values used to drive the case structure are working correctly." - This implies that his hardware works.
And
3. Even in his second post he repeated to you that "the motor will turn in reverse if supplied a negative input value (from control)" which you again ignored!
So you see - not only that one of my degrees is in Electrical Engineering with over 24 years of industry experience in this line, I'm even able to comprehend simple sentences! Someone with a lower number of total posts than you doesn't necessarily translate into them knowing less than you, there is no need to start posting intimidating messages... even if you had 50,000+ posts.
-DP
(However, I was incorrect in my explanation on items circled in red on my first image - I meant to say that it will allow only negative values to go through and replace any positive number with a 0 - this is most likely why the motor doesn't reverse when wire values are fed.)
