No active M3 code in LinuxCNC Status or under MDI tab

I am currently changing over from Mach 3 to LCNC, my plasma torch fires as expected from the manual spindle CW control button, but the torch is not firing at all when running gcode. The probe routine and subsequent XY movement are fine, it's just that my torch won't fire.

A couple of things I noticed were that, among the 20 or so active G-codes under the MDI tab, there is no M3 code, although M5 is shown.

Also, I happened to notice under Linux CNC Status tab, under Machine that there is no M3 code shown under the Mcodes listed.

Any idea why I seem to have no M3 function? I'm using version 2.7.

Sounds like you need to add an M3 to your gcode. Also you might also need to set the spindle at speed signal
In the example below hm2_7i76e.0.7i76.0.0.output-04 is connected to my torch on relay
Whilst there are a number of ways to turn the torch on via Gcode, using M3/M5 is the best way in my view becasue it gets dropped if you hit estop.

Nothing worse than having a crash and the torch is flying around still firing and the plasma machine is in the other side of the table

Hi Rod,

thanks for the fast reply, I should have mentioned that I do have an M3 and M5 in my gcode same as when I was running Mach 3 until I lost a hard drive and my windows 7 64 bit installation needed to run Mach 3.

I'm using the Sheetcam post for LinuxCNC. Neither Axis or GMOCappy plasma configs are showing active M3 in the MDI or under the "Check LinuxCNC Status" found under the Machine tab.

I've not used that sheetcam post.

The spindle does not move until it gets a speed.
Do you have an S command in there somewhere?
Try adding a S100 in your g code if not.

Here you can see my G & M codes in Status and the MDI where no M3 appears to be available. The S0 is available.

I've tried other posts with the same outcome, maybe I need to update to a newer version of LinuxCNC?

Edit: I just did a google image search for linuxcnc mdi, it looks like M3 is not usually listed as an active G-code anyways. So my problem must be somewhere else.

M3 starts spindle
M5 stops spindle
You will ( hopefully ) never see both active the same time.

And have you set a Sxxx for the M3 as rodw proposed?
Mike

I'm working on figuring out how to do that now, I think it's something I have to add in my post in Sheetcam?

The G & M codes you are looking at are just the initial config codes that are set in your ini file so the system starts in a known state.
The post you are using may not be correct for your machine. Its just a text file that can be edited.

Lets start at the beginning. Turn your plasma off for now.
Open up Halshow (menu should be "Show Hal Configuration")
Select the watch tab and click on motion.spindle-on in the tree.
Go to the MDI window and type S100 then M3 and then M5 each on a new line. Does the signal go on with M3 and off with M5?
Assuming you pass this step (and you should) the next step is to connect that signal to to your torch on relay.
If you don't pass this test, you have not defaulted the spindle at speed to true as I showed you.

what is the name of the pin you have connected to your relay? Please tell us.
Please also find this pin in halshow and add it to the watch list.
And have you connected motion.spindle-on to your pin as I showed you?
Now watch that pin connected to your relay. Does it go on and off with M3 and M5 in the MDI window?
If you pass this test, the next step is to grab a multimeter and check that the relay coil is receiving the trigger signal.
Then finally, check that the relay contacts are closing. Do you get a change in continuity with M3/M5?
I have found if you follow the process one step at a time, you will eventually solve the problem

Sorry, I am slowly catching on. Editing the M3 so that it is followed by S100 in my sheetcam post worked as Rod suggested. I have a functioning torch again. I really appreciate the help guys!

Great work. And congratulations on moving to LinuxCNC and building a working machine !