Quote Originally Posted by Ger21 View Post
Most controls can do some parametric g-code. But it appears that Macro B gives you access to just about every thing the control is doing, through variables.
Yes, macro b isn't just variables, though it is that too. It also is access to system variables (eg., on a 2 pallet HMC, you can query: what pallet is currently inside?). Also, variables #1-#99 reset on power cycling, but #500-#599 do not. That is very useful for certain times you want information to survive regardless if power is interrupted. Access to just about everything in the control, and you can also have external I/O write to macro variables, depending on their state.

In the old days, people did their entire robot interface and gauging interfacing through m-codes and variables.