Can't tell you about the functional differences between the D3/D4 as to operation of the control...
Never had or used a D3 machine. No manual for the D3 either so no info from here on that score.
You can upgrade form a D3 to a D4, but it would be expensive i think.
The "upgrade" is not a software thing, but rather a hardware change.
The upgrade would require (to the best of my knowledge) the re[placement of almost all the boards in the operators console.
Think the board for the display (NCR) will work across both control versions....pretty much everything else must be replaced.
Console keypads can remain, but overlay stickers will be needed to properly label the new key functions.
There will also i believe be the need to fit the small board (MH50) in the base of the control that has to do with the MPG along with the ribbon cable K7/K8.
Believe that all the parts in the large cabinet will work with either control.
The Bosch servo drive as well as the "PC" will interchange no matter if the PC is the first gen (PC1) or second gen (PC2).....
For stability, I think the software (E-Prom) change would be a good idea for both the control and the PC so everything would match, but in reality i have run a D4 machine off two different main electrical cabinets
having either a PC1 or a PC2 and either ran with zero issues.....
Thought someone would chime in here...But think to my best knowledge the biggest difference is the ability of the D4 to do real 3-D contouring....and the way cutter comp is handled.
Not sure if a D3 is capable of storing multi programs on the control, i know that D2 can only store one program at a time.
Also small side note...D4 can run both D3 and D4 programs .
Would think the best chance to upgrade a D3 control to a D4 would be to score a complete operators console from a scrapped machine or from someone who thinks they are going to retrofit a
D4 machine and are selling off the "obsolete" parts......
Cheers Ross
