Hi,

I have MACH3 setup to output #1 & #2 on pins 16 & 17 respectively, they both run through an identical transistor/relay circuit and are used for spindle and coolant control. The circuits seem to work fine and switch as requested by MACH3.

The problem is that if I use both then it messes up the Z axis, sometimes it moves very jerkily and sometimes not at all when commanded.
If I use only 1 of the M03 or M08 commands then the Z axis runs fine, it doesn't seem to matter which I run.

I don't think it is a power problem as the switching circuits only take the 5v signal to switch the relay and they seem to be switching fine.

Has anybody come across this type of problem before?

Thanks
Simon

I have just built a four relay driver board, using a darlington array to drive four 5 volt relays for motor and coolant control.
I am using pins 8 and 9 for M3 and M4 and pins 16 and 17 for M7 and M8. (I think I might have damaged pins 1 and 14 earlier)

Pins 8 and 9 seem to work fine and M3 and M4 are reliable. When  I was testing M7 and M8 commands, I sometimes got intermitent results. It seemed that I could get M7 on, but sometimes M8 would only go on if M7 was on. M9 turned both off. I don't know how Mach3 interprets this Macro.

I would try using say pins 8 and 9 and see if you get the same results, or put the Z drive on a different pair.

I must admit I cannot see how this would be affected though.