step voltage control

[Toyota]

Dear Members,

I am a new labView user and I am using LabView 7.1.I am trying to control the power supply voltage with step voltage around 0.01 V and stays for 100 ms on every step from

(1) 0 to +10 v
(2) +10 V to -10 V
(3) -10 V to +10 V

For instance , I begin with 0 volt and want to control the power supply as the above 3 steps.

My question is The results seem to be out of my control , since it should stay quite few  ms  and start measure　after few delay time. But the curve seems to show some spikes in some step voltages. Another problem is I set up maximum 10 V and after step (3) it should automatically reset to 0V since after measurement , it stays on 10 V until I manually reset the voltage to 0V.


I wonder if any suggestions would be very great.

Sophie

I have attached the labview VI for your attention.

[Albert.Geven]

Hi

A subvi called "Loop_field control_stepV(test field).vi" is missing
Now it is difficult to see what hapens

[Toyota]

I am so sorry, I forgot to attach it. I will attach it now. I think this sub VI took time in overall measurement. If ramp function is possible, I would like to try instead of using it. Please let me know kind suggestions upon this issue.

regards,
Sophie

[Albert.Geven]

Hi

Ok, although still tat least two vi's are missing, I can see the flow now.
Why do you have two while loops in this lowerlevel vi that does some measurement and IO
This should be handled by the main program that already has too many while loops.

Can you tell in words what are you trying to program?

[Toyota]

Hello,

Thanks for your reply. This step voltage VI is part of my main program. I used and modify the program that previous person created.Please let me explain my intention

(1) It controls  the power supply Unit (PSU) and as I memtioned in the previous,

from 0 10 10 V; 10 V to -10 V and -10 V to 10 V by small steps like 0.001V or 0.01 V or  0.1 V or 1 V gradually increase and decrease  until these three steps from 0 to 10 V; 10 V to -10 V and so on. My maximum limit is 10 V.

(2) This PSU is connected to the machine and I measure the output DC voltage by a HP 34401 A. For example, I made a step voltage , and then I wait for a while( delay time ) and made measurement.

(3) That why it is not included in the main program, its function is just supply step voltage as three loops from 0 ~10V~-10 V~10 V.
(4) I could not manage to stop at 10 V , sometimes it exceeds to 11 V and it did not stop and initialize to 0 V automatically after measurement finished.

Please let me know your opinion upon this issues.

regards,
Sophie

[Albert.Geven]

Hi

I try to build a small example with correct coding style
I concentrate on the voltage control with reading of the voltmeter.

! I don't have the magnet control vi so I leave that to you.

[Toyota]

Hi   !

Thanks in advance. Could you kindly attach the example VI? I am using labview 7.1.

Sophie

[Albert.Geven]

Hi Sophie

This is the example
If you start the vi you see the voltage steps in the graph (no timing)
YOU can edit these steps by changing endvoltages and stepsize!
if you press start the samps are replaced by the measurement
if you press abort the already measured points are saved and the vi stops.


PS (if simulate is checked it will perform no real IO and the MagField should be changed to do something !)

[Toyota]

Hi Mr.Albert,

I really appreciate your help . I am a new labview user and your contributions made me so much impressions  about your knowledge, creation and  LabView and its applications. I hope my labView level is quite low in order to understand all steps in your example. Please let me ask you if I find difficulties .

I am trying with your example as soon as I received your message. As part of my program, I need to supply step voltage to power supply unit which is connected to magentic field and then I measure the applied magentic field as a voltage by HP . In order to get that procedures , I tried to  connect generate step voltage VI with Power supply unit VI and I could not manage to do. So far, I need to get curve continuously (step voltage from 0~10;10~-10 and -10 ~10 V).  I am confusing how should I control power supply before measure by HP ? Should I need while loop with shift register?

Please let me know your opinion? I have attached power supply VI for your consideration.

I appreciate your time and effort.

Sophie