I ran into an interesting problem with my series 1 1100 recently. Since I find this forum a valuable resource for knowing about problems before I encounter them, I thought I'd share.
When running a part, when time came for a tool change, the spindle would rise to tool change height on M998, but wouldn't stop the spindle on xxxM06. While Mach would show the new tool number to put in, it would also show the spindle running. So this wasn't a comm glitch, Mach said the spindle should be running! Now, this code had worked fine for innumerable parts before hand (production). What changed?
It took a few hours of fiddling, but I tracked it down to a corrupted tool table in Mach. The telltale sign was in the Tool Table window. There is a header above the columns, saying Reference tool #0, and 0.000 above each column. Well, mine said -9378563 or some such above each column. It's not even an editable field!
Going back to the main screen, I entered tool #0 as the active tool, did a couple of other tools, entered tool #0 again. Back in the Tool Table window, things read right again, 0.000.
Apply, Save, closed Mach, opened again, checked, good to go. And it's run fine ever since. So apparently, the M06 macro was getting corrupted when it accessed the tool table, and aborted.
just in case anybody else runs into this, this is what fixed it for me.
Thanks for posting your issue and solution. I am sure your post will save someone much time and frustration.