Data following graph data

[MJBrehm]

Hey Everyone,


I am currently writing a LV applcation to control an AC motor. I need to be able to set a max/min value for the motor speed, and have a set time that the motor stays in each max/min value. I would also like the speed of the motor, along with the max/min "square wave" I specified, graphed together. Basically to track the response of the motor in relation to the square wave. It seems like an easy enough problem, but I have been using LV now for about a month. I come from a heavy OOP background and still getting used to the finer details in labview that Im sure would make many of my programming delemmas a whole lot easier to solve.

I have tried to create a digital waveform, and link that to the motor controls while graphing both. Controlling the motor isn't the problem, it's creating a waveform that controls the motor. Maybe that's a better way to ask the question. How could I control the motor based off a graph? I want the motor control to follow the graph. Ug, this is frustrating.

Any help would be great... Ill continue to bounce my head off the desk in the meantime. Thanks!


Matt

[gwd]

It's hard to get detailed without knowing more about your system...but maybe you want an analog step function instead of a digital one. You can create this as a waveform using Square Waveform.vi. After all, your speed measurements are going to be analog and it will be less trouble to plot two analog things together.

[MJBrehm]

Thanks for the quick reply.

Basically, I want to specify a max speed the motor ramps up to. It should stay at this max speed for a time the user specifies. After that time the motor should ramp back down to a min speed the user specifies. It should then stay at this min speed for a time the user specifies.

So basically the motor speed should be be oscillating back and forth between the two values. Then when matched up against the square wave it is following, it will show the user how responsive the motor is. Because the motor takes a certain amount of time to ramp up to the max speed, often it over shoots its target, and then oscillates up and down trying to match the specified speed. Or sometimes it won't ramp up quick enough between speed changes and you get these logorithmic looking curves up and down.

It could be something as simple as a timer setup. Im just looking for something I might be looking over. Or another idea on how to do it... Im definetly open to suggestions... thanks.  : )

Matt

[MJBrehm]

I know its not the most graceful of solutions but I did get something to work. Just threw an express timer VI and linked it to a case structure. This way I could set the timer, after the set time it would enter into the case structure and change the value of the speed going to the motor.

I feel like I know how to get things done in LabView... I just don't know how to get the done right/well.

Thanks to those that replied or even took a second to read.

Message Edited by MJBrehm on 05-11-2006 03:16 PM