How to read controller name?

Can i read control unit via a variable or parameter? ( 5020L, 700M , P200L etc. )

very good idea. In case if someone replaced the OSP suddenly, the part program can recognise it and salute the operator :-)

Not that I'm aware of. However some spec codes do reveal info about the control so that would be possible to check. What are you trying to do?

For use some special codes for all controllers don't need write different program.

most of the Okuma controllers are compatible in some way. you can put a simple program with the exact same code into most Okuma machines of the same type and it will work (just like Fanuc is also compatible with any Fanuc controller for the most part). there isn't any known way to identify the controller via a command or variable.

I would check the specification code for that. The same model could have through spindle air blow for instance, o could not have it.
Or, the parts catcher for lathe - depends on the specification, not on model.

specification/options can be different but even with a list of options the model control or machine would not be known. the G/M codes that are used are exactly the same. For example G141 means right chuck work and that code is universal on all twin spindle Okumas like LT/Macturn/Multus etc. Some models have different controls (i.e. Macturn can have OSP-P100L, OSP-P200L or OSP-P300L). So checking the code or specification to determine the control model is not possible, and there aren't any known variables like a control model number so the conclusion is its impossible to check a machine or controller model based on the program code or a variable. Program that runs on Macturn with OSP-P100L will also run on Macturn with OSP-P300L..... assuming they have same spec/options, programs are compatible across different controls and machines.