Control global variable used in sub vi

[BassBijj]

Hi,

I've created a vi to read an instrument and to initiate its calibration with labview. This VI stores data in a global variable containing measurments and status of the instrument.

Now what I'm trying to do is create a sub vi with this to read&write 2 exactly identical instruments so I can finally create a VI that read all 3 instruments simultaneously.

How could I create a control on the global variable used by the sub VIs since it is the only thing that will change along with its COM port ?

I included a screetshot of the current VI.

Thanks,

[crossrulz]

I would make an array of values and then you just pass in which value to update.  I would actually take it a step further and make an Action Engine that can update the data and return the data.