Mach3 Problems problems problems.

[Clive S]

Whilst running a small program with G20 in the first line the program executes moves that are wildly incorrect. A move of Z0.100" makes the Z axis move continually in the + direction until physically stopped by operating cycle stop. After lots of messing about a G21 was inserted in the second line of the program. It worked perfectly and accurately in Imperial moves. Absolutely no idea why!!!

Before you start setting the soft limits you need to check what is setup wrong. You seem say when using G21 you are getting accurate moves with inches. Are you saying that if you command the machine X0 2 it moves 2" or 2mm?