topic Re: Using LabView to serial interface my microscope how I make a user interface to make the stage move by pressing buttons? in LabVIEW

Using LabView to serial interface my microscope how I make a user interface to make the stage move by pressing buttons?

HumanCondition — Mon, 28 Jun 2010 16:10:30 GMT

I have used LabView very little and am trying to write a program to control a microscope. I want to be able to give it commands such as to get the stage to move left, right, forward, back, and return to zero. I'm having trouble implementing the code into my block diagram. I've been reading LabView 8.6 tutorials for a couple of weeks and I'm still learning. What I know that is that I need a event structure inside a while-loop for the user interface but I've been stuck.

Thanks for any help! If you need me to try and provide more information please say so.

Re: Using LabView to serial interface my microscope how I make a user interface to make the stage move by pressing buttons?

RavensFan — Mon, 28 Jun 2010 18:41:33 GMT

You've got two major problems right now. Your serial port code is all outside of the while loop, so it will only execute once. Also, you have a race condition with your VISA writes. Will the command get written first to the serial port or the carriage return?

The rest of the code is just too incomplete and a mashup to even comment on.

If you know you need an event structure in a while loop, then why not post your best attempt at that, then we can comment on how to make that better.

Re: Using LabView to serial interface my microscope how I make a user interface to make the stage move by pressing buttons?

HumanCondition — Mon, 28 Jun 2010 19:28:25 GMT

Alright so my serial port code should be inside a while loop unfortunately it doesn't work whenever I enter a command to move the stage. It sits there maybe I'm missing something.

So let me give you an overview to what happens in my code, so the configure serial port is very crucial. The VISA Write writes the bytes to the port. The first VISA Write takes the string to write command. I connected the second VISA write to make it easier whenever I enter a command, the \r will iniate the command as a whole. Example L\r will move the stage to Left once, ending up at VISA Read then closing. All of this found in separate case structures.

Now the user interface to control the the movement of the microscope is one of my issues, making several attempts to make it work yielded no results. My best work not the best but a attempt is attached, also one of the things with this I'm having trouble with is getting the button to talk to the stage. On previous buttons I worked on I could press the button and light up an LED on the front panel, I thought the same principle would relate to the movement of the stage, no such luck.

I hope I cleared up some misconceptions on my part, I appreciate your patience.

Re: Using LabView to serial interface my microscope how I make a user interface to make the stage move by pressing buttons?

tbob — Mon, 28 Jun 2010 19:36:19 GMT

In your Write case, you have two separate write funtions, one for the command and one for \r. They both run in parallel. Which one will run first? Will it be cmd then \r, or will it be \r then cmd. This is probably why it isn't working. You don't need two write functions. Use Concatenate String function to combine your command then \r into one string. Use one write function. This will send the proper sequence of cmd\r.

What is your bottom loop supposed to do?

Re: Using LabView to serial interface my microscope how I make a user interface to make the stage move by pressing buttons?

Dennis_Knutson — Mon, 28 Jun 2010 19:45:19 GMT

None of that makes any sense. Your serial write/read will still only execute once, you did not create an event for the 'Left' button, and that conversion to an array, search array, to number code is just silly. The concantanate string in the top true case is also silly. What do you think that does?

Look again at the examples. You want an event for each button and inside each event, you want the indicator and the VISA Write of the command that corresponds to that movement.

Re: Using LabView to serial interface my microscope how I make a user interface to make the stage move by pressing buttons?

HumanCondition — Mon, 28 Jun 2010 19:46:16 GMT

In the Write case I have them both running parallel you would enter the cmd and then \r would be attached to it. Alright I understand I fixed that it less clutter now.

The bottom loop I'm attempting to interface that so I can press a button such as left to move the stage left. Yet I have not yet figured out how to incorporate that into the program. I need some help on that part, I get the basics on it but I'm at a loss.

Re: Using LabView to serial interface my microscope how I make a user interface to make the stage move by pressing buttons?

Dennis_Knutson — Mon, 28 Jun 2010 19:54:51 GMT

Now you have NO event structure. Try to do what I suggested with the VISA Write inside an event. Do NOT place any code outside the event structure like you had before.

Re: Using LabView to serial interface my microscope how I make a user interface to make the stage move by pressing buttons?

tbob — Mon, 28 Jun 2010 19:55:41 GMT

You need an event structure. Put a button on the front panel to allow the user to first enter a command, like L to move left, then the user would press the button (OK button) and the event would fire. Put your serial write code inside the OK Button Value Change event. So after entering a command, the user presses OK and the command is written.

I will create a small example for you.

Re: Using LabView to serial interface my microscope how I make a user interface to make the stage move by pressing buttons?

HumanCondition — Mon, 28 Jun 2010 20:03:06 GMT

Alright so now I need to improve it previous suggestion was to put the all the code into a while loop. Previously I was doing work, the stage was moving and the commands were being taken. The concantanate string has been fixed. Building off this LV example is what I've been working on, yielding good results but no luck on needing the stage to move by pressing a button is part of my problem.

Ok that advice is sound I'll take that and let you guys know. I appreciate the help.

Re: Using LabView to serial interface my microscope how I make a user interface to make the stage move by pressing buttons?

tbob — Mon, 28 Jun 2010 20:12:39 GMT

Look at the attached vi. It uses an Event Structure. Study it. When the user presses the OK button, the OK Value Change event runs and the command is sent to the serial port, followed by a serial read. Then the loop iterates again, and since no event is happening, the Timeout event runs. No code here so nothing happens over and over again until the user presses a button. The user can enter a new command then press OK. Or the user can press the Stop button and the Stop Value Change event will run. This will stop the loop. After the loop stops, the VISA session is closed. The shift registers for error and session handle are highly desired to transfer the data from each loop iteration to the next.

Re: Using LabView to serial interface my microscope how I make a user interface to make the stage move by pressing buttons?

HumanCondition — Mon, 28 Jun 2010 20:22:54 GMT

I'm sorry to trouble you but I have LV 8.6 is there a way you could create a backwards compatible Vi? Please and Thank you.

Re: Using LabView to serial interface my microscope how I make a user interface to make the stage move by pressing buttons?

tbob — Mon, 28 Jun 2010 20:25:26 GMT

I can do that:

Re: Using LabView to serial interface my microscope how I make a user interface to make the stage move by pressing buttons?

HumanCondition — Thu, 01 Jul 2010 20:42:18 GMT

Sweetness worked out flawlessly. Thank you tbob.

Alright now, I had a question on how on the same project, but now I'm attempting to have an indicator to report the position of the stage on my microscope in the x,y,and z axis. I want it to automatically show up instead of pressing a button. Just whenever I have the program on it should report the position, when I move the stage by command, or by button, or by joystick. Basically attempting to set it it up where its on at the same time the microscope is.

The while statement is the best I came up with. If you have any hints you can give me that would help. Please and Thank you.

Re: Using LabView to serial interface my microscope how I make a user interface to make the stage move by pressing buttons?

HumanCondition — Thu, 01 Jul 2010 21:33:44 GMT

Ok, I'm close to figuring this out I think I have it now where I'm able to get numbers x,y,z everytime I move the stage but now I need to convert the string to numeric. To be shown on the numeric indicators. How can I do this?

Re: Using LabView to serial interface my microscope how I make a user interface to make the stage move by pressing buttons?

tbob — Thu, 01 Jul 2010 21:35:43 GMT

How is the value of X, Y, and Z changed? Maybe by the buttons labelled Back Left, Backward, etc..? How much does it change by? You will have to have 3 shift registers, one for X, one for Y, and one for Z to hold their current value. When the axis is changed, update the value and pass the new value to the shift register. The best place to do this is in the event structure. This is where the movements are captured. As an alternative to 3 shift registers, you could bundle the 3 axes into one cluster and use one shift register for the cluster. Then when one axis changes, unbundle that one element, change it, then rebundle.\

On your event, X-AXIS, Y_AXIS, Z_AXIS Value Change, since the values will be changed programatically (not by a user pressing an x-axis button) you will have to change the event to value(signaling). Use value(signaling) whenever the program changes the value rather than a user changing a control value by clicking on a control or button.

Re: Using LabView to serial interface my microscope how I make a user interface to make the stage move by pressing buttons?

tbob — Thu, 01 Jul 2010 21:45:54 GMT

@HumanCondition wrote:

Ok, I'm close to figuring this out I think I have it now where I'm able to get numbers x,y,z everytime I move the stage but now I need to convert the string to numeric. To be shown on the numeric indicators. How can I do this?

Look in the palette called String - String/Number Conversion. There are lots of conversion functions there.

Re: Using LabView to serial interface my microscope how I make a user interface to make the stage move by pressing buttons?

HumanCondition — Fri, 02 Jul 2010 16:09:47 GMT

tbob wrote:

On my event structure value(signaling) isn't an option it might be because I'm on LV 8.6. The problem is solved now, but not the way it should be I'm interested in the value(signaling) but it isn't an option should I just stay on what I have or find a better way?

Re: Using LabView to serial interface my microscope how I make a user interface to make the stage move by pressing buttons?

RavensFan — Fri, 02 Jul 2010 16:20:18 GMT

No.

Value(Signalling) is the property node you write to of a control or indicator (as opposed to just Value, or writing to the control's local variable) in order to have the Value Change Event of that control get fired.

Re: Using LabView to serial interface my microscope how I make a user interface to make the stage move by pressing buttons?

tbob — Fri, 02 Jul 2010 18:01:08 GMT

@Ravens Fan wrote:

No.

Value(Signalling) is the property node you write to of a control or indicator (as opposed to just Value, or writing to the control's local variable) in order to have the Value Change Event of that control get fired.

I didn't explain it very well. Brain fart moment. Thanx for clearing it up RF.