LabVIEW
Why won't my formula node work?
You syntax is incorrect. The "=" should be "==". What you're doing is an assignment, which is always true, so each of your if statements is being executed.
A better way is to use an enum which you can then format directly into a string using the Format into String function, like this:
(1) Use the error clusters to establish data dependency flow. You can eliminate all of your sequence frames this way.
(2) Why are you using local variables to access front panel controls? Just wire to the terminals. You're just creating more memory usage.
(3) If you switch to the enum for the above you can simply have an array with the corresponding values that you can index to get the value to feed to your arithmetic.
A better way is to use an enum which you can then format directly into a string using the Format into String function, like this:
<added>
After looking at your code some more, a few points:(1) Use the error clusters to establish data dependency flow. You can eliminate all of your sequence frames this way.
(2) Why are you using local variables to access front panel controls? Just wire to the terminals. You're just creating more memory usage.
(3) If you switch to the enum for the above you can simply have an array with the corresponding values that you can index to get the value to feed to your arithmetic.
Message Edited by smercurio_fc on 03-27-200601:13 PM
npai:
your modification will break the VI, because the value of the control is used elsewhere via local variables.
JohnGalt:
You could just take the log (base 10) of the value and then make cases for 0, -3, -6, and -9. Attached example (LabVIEW 7.0) shows one possibility.
Some general comments (as implemented in my modification).
- There is no reason to make the "units of I" control EXT (extendend precision). Keep it a DBL.
- I don't think the user should be able to change the values during runtime, so the terminals should go outside the FOR loop.
- Avoid all these sequence structures. They hide code and make the VI hard to debug. You can fully define execution order using the error cluster of the VISA functions. Think dataflow!
- Avoid all these local variables.
- Don't forget to close the file when done.
- Do the string cocatenation outside the case structure to avoid all that duplicate code. Code that is identical in all cases must go outside the case structure.
Additional suggestions:
- You might want to replace the FOR loop with a WHILE loop so you can stop (1) on error or (2) when the desired number of iterations have completed or (3) if the user want to abort.
- Depending on how fast this loop runs, place an indicator in the iteration terminal so the user can monitor the progress.
- ...
My example is just a quick draft, please verify correct operation and modify as required.
This is another reason why local variables should be avoided unless absolutely necessary. Mistakes like this can occur easily when the VI is peppered with locals. 😞
No harm done, since JohnGalt apparently only has LabVIEW 7.0 and you posted in version 8. 😄
