Could we create polymorphic VIs in LV 8.0?
Yes. More specifically, DAQmx came out about that same time and it was (and still is) very Polymorphic VI heavy. I think DAQmx even worked on LabVIEW 7 (Express).
But over the years, things have changed into polymorphic VIs. So if you try to convert one of those, you can run into this error.
You don't specify how much time you spent "modifying" the program, but I bet you could do the same changes in less time directly on the LV 8.0 computer in the lab.
I like this idea. You're gonna end up debugging, troubleshooting, and almost certainly modifying on 8.0 in the lab anyway. If you have LabVIEW Professional, you could also copy the original 8.0 code from the lab PC to your laptop and compare the two pieces of code using "visual differencing". (Note: you'll need the vi's to have different names or else open them from distinct projects.)
Using your laptop as reference, you can be sure to catch all the mods.
If mods are going to be frequent, *and* it's important to do some of them offline away from the lab, you'll probably want to work out a better system for the long run.
It specifically complains about a polymorphic VI, so you can remove that problem by using the polymorphic instance directly (probably).
Excuse me, I am new to LabVIEW, and I don't exactly know what "polymorphic VI" means. I know polymorphism means, for example, I can connect add function with an array and a number, then the result is that all the elements will add that number. But what about polymorphic VI?
A polymorphic subVI is one that has several underlying VI's that allow it to adapt to the type of data coming in.
If you look at DAQmx and when you see the Polymorphic VI selector is shown, you can select from different instances like Waveform vs. arrays, vs. different array types, 1 channel vs. multi-channel, 1 sample vs. N samples.
Go to the Help Menu >> LabVIEW Help ... Search for "polymorphic".
That's trying to go back a long way. Wouldn't it be simpler to just get a copy of LV 8 from NI? I believe you can get older versions of LV from NI if you have a current license for a newer version.
You mention your intent is to run your modified program on the original machine (XP). XP is also compatible with versions up to LabVIEW 2011 or 2015 depending on your service pack. Perhaps your problem will be resolved by using a version newer than 8.0, but still compatible on your target machine.