real time velocity

[Carmen92126]

I'm brand new to LabVIEW. My first post here. Hello world ! I'm using LabVIEW to control a stepper motor for a user defined velocity and acceleration. I need the instantaneous angular velocity of the motor. There is a string that goes to the serial port. I think I need to "tap" into this string with a Y. I want the "tap" to then convert to a decimal number which will go to a visual output. My final goal is to make a graph of velocity v time. Thanks for help. Carmen

[LV_Pro]

Do you have any code you can show us? If you have, within your LabVIEW code, a string that is going to a serial write function, then it would be easy to display the values in that string, etc., but depending on how that string is generated you might want to do it another way. As to getting the instantaneous angular velocity of the motor, how do you think that you will get that by tapping into a serial command to, presumably, a motor controller? It would only tell you what you've asked the controller to command the motor to do, nothing about what the motor has/is actually doing.

[Carmen92126]

Thank you for you reply. OK, I learned that a string is just a one-time command that is sent to the stepper motor indexer. From there the indexer computes how to actually control the motor, and the indexer is the source of the real-time data I need. So, I must query the indexer for the motor velocity. I think that LabVIEW must query at given time intervals, say 0.1 seconds, and the indexer will return the answer, presumably the angular position or step. With that info, LabVIEW will calculate angular velocity based on the time elapsed between changes in position. Then LabVIEW can also calculate the linear velocity based on the shaft radius.

Thank you so much for your help.

[Kimberly_Wenger_Austin]

Hi bottleofarduino,

As far as graphing velocity versus time, you can easily create an indicator off of the velocity function with a representation of double and replace the value with a Waveform Chart.  This will graph the velocity versus time. I am not sure that I understand any other questions that you have, so please let us know if you have others.

In looking at your VI, it is missing the sub VI called step_drive.VI, which is not that big of a deal, but I also noticed that you have the stop button wired to a loop control which was hidden.  How do you stop your VI?

Thanks!

Kim W.

[Carmen92126]

I need to figure out how to query the indexer that controls the stepper motor. The model indexer is a Parker Computmotor, Microstep Drive, AX Series. Any suggestions? Thanks so much.

[Kimberly_Wenger_Austin]

Hi, 

Do you have a full motion system configured with a motion controller?  What is your current setup?  This Developer Zone should be helpful for conifguring your third party drive with our hardware.  As far as communicating to the motor, this should get you started with communicating to the device.  I do not know of a specific query that you can send to the device, but you can easily command moves to the motor in LabVIEW or in Measurement and Automation Explorer.

Kim