Factory Pattern on a VI running on RT target

[Renny Sadala]

Hi everyone,
I have a myRIO that i try to use to implement a factory pattern of OOP.
I have to classes that i need to load dynamically on the VI running in the RT target.
Firstly, i saved my classes in the myRIO's memory on the path /home/lvuser/natinst/bin/Host_Class in the directory Host_Class.
And i give to the VI "Get LV Class Default Value" this path but i had this error : 
Error 7 occurred at : Get LV Class Default Value.vi

Possible reasons :

LabVIEW: (Hex 0x7) File not found. The file may be in a different location or may have been deleted. Use the command prompt or file explorer to verify that the path is correct.
=========================
GPIB interface not existing.

LabVIEW tried to load the class this way:
/home/lvuser/natinst/LabVIEW Data/Host_Class/Accelerometer/Accelerometer.lvclass

But when i check this directory, my classes are there

[Neil Pate]

I am a bit confused. You said you saved the classes to:

/home/lvuser/natinst/bin/Host_Class

but then you tried to load them from

/home/lvuser/natinst/LabVIEW Data/Host_Class/Accelerometer/Accelerometer.lvclass

These directories are different...

Edited August 12, 2020 by Neil Pate

[Renny Sadala]

Sorry,

I saved my classes at /home/lvuser/natinst/LabVIEW Data/Host_Class

[Neil Pate]

I have never actually tried to use the factory pattern on a cRIO. So much trouble getting it to work properly just under Windows I have never been brave enough. Do you absolutely have to do runtime instantiation using names? Have you tried a static VI reference?

[Renny Sadala]

I'm coding some pretty complex software. That's why I choose the object-oriented approach.

And the factory pattern will help to achieve the flexibility that i need.

[Neil Pate]

Sounds interesting. Sorry I have never tried to dynamically load classes in RT, I have enough trouble these days just getting normal code to deploy without stupid un-explainable errors in LabVIEW.

For some reason my RT VM is not cooperating and I cannot copy any files across to test. Have you tried to load a very simple class? I presume you have some kind of HAL with inheritance? Maybe the error is because it is missing some dependencies? (I know error 7 is missing file though, as you mentioned).

Have you tried loading the class with the 0x10 option?

[JKSH]

5 hours ago, Neil Pate said:

For some reason my RT VM is not cooperating and I cannot copy any files across to test.

As a workaround, you can transfer files into a USB stick from your host, and then attach the stick to your VM.

[Renny Sadala]

I resolved my issue.

I must placed my la class file (.lvclass) on the root of the folder /home/lvuser/natinst/bin/ that is the default directory that the RT reads. 

[Neil Pate]

I am not sure I follow you. Are you saying an absolute path on RT does not work when trying to load the class from disk?

Can you not load the class from the /C/ or similar? That seems weird!

[Renny Sadala]

Previously, i loaded the folder containing my all classes (for example the folder Host_Class). I had placed this folder in the path /home/lvuser/natinst/bin/. I.e I will had  /home/lvuser/natinst/bin/Host_Class

Now, i place directly my classes in the path /home/lvuser/natinst/bin/  and not via a directory like Host_Class.

Apparently, By default, when RT target runs, the reading is limited only to the path specified in the RT target properties. In my case, this path is /home/lvuser/natinst/bin/

 

 

 

Edited August 13, 2020 by Renny Sadala

[Jordan Kuehn]

18 hours ago, Renny Sadala said:

Previously, i loaded the folder containing my all classes (for example the folder Host_Class). I had placed this folder in the path /home/lvuser/natinst/bin/. I.e I will had  /home/lvuser/natinst/bin/Host_Class

Now, i place directly my classes in the path /home/lvuser/natinst/bin/  and not via a directory like Host_Class.

Apparently, By default, when RT target runs, the reading is limited only to the path specified in the RT target properties. In my case, this path is /home/lvuser/natinst/bin/

 

 

 

You might check the folder permissions for the folder you created. I have ran into issues with that before.