Hey Dan,
you can click the download link (spindle_warmup.ngc) in my above post, save the file on your computer, put the file on a USB stick and upload it to the CNC controller. On the buildbotics-derived Onefinity Controller of the Original and PRO Series, you can also have a SMB share somewhere in your local network with g-code files, or when connected from a remote computer, simply upload it from the computer you are on. I don’t know what options the MASSO has to do such things. Maybe you can also program a macro in your Controller, in this case you would enter the code into the macro field, but I don’t know the MASSO as I don’t have one (nor do I plan to buy one). On the buildbotics-derived Onefinity Controller of the Original and PRO Series, Onefinity works on a firmware update that supports macros so you could simply have a “spindle warmup” macro button. What you can do on the MASSO G3, is to have an autoload.nc program that is run when you power the controller on, you could put the g-code there. In this case I would add a line at the beginning that says…
M0 (msg, Run the spindle warmup program?)
…which would make appear a popup window and wait until you first click the “okay” button. The MASSO Documentation page mentioned above also describes assigning g-code programs to real hardware buttons that you can attach at input terminals of the controller, this way you could implement a “spindle warmup” button.