External EStop Requested

[ALR]

I have now been able to run my home built CNC router.  I am learning to use Mach 3 and the machine.  I loaded the Roadrunner.tap g-code that came with Mach 3 into the machine and without the router powered the program went through the program without issue.  I put some material in the machine and set the soft limits to the material and started the program with the router running.  About 1/5 of the way through the code the program stops and the reset button is flashing with a message saying "External Estop Requested".  None of the limit switches have been triggered.  I can turn the router off and can reset the program.  Within seconds of turning the router back on the reset light flashes with the same message.  This is with no movement of any of the axis.

The diagnostic screen indicates that the e stop switches are not activiated.  I can manually trigger the estop ligh ton the diagnostic screen by manipulating any of the switches.

The power cord for the router is no where near any of the wires for the z axis or limit switches, so I don't think it is electrical interference causing the problem.  However, since the problem only occurs when the router is powered, I suspect it has to be electrical noise.  I have also checked all of the electical controls and none are elevated in temperature.

Does anyone have any suggestions on how to get around the problem?

[Hood]

Two things it could be, one is electrical noise the other vibration. Both of these could be making Mach see a limit switch input. Mach is fast and you may not even see the LED on the diagnostics screen light as its too fast to show.
Best course of action is to make sure your limits and E-Stop wiring is properly shielded and grounded but you can also set a debounce interval on the General Config page. That will make Mach ignore signals unless the persist for longer than the time set, try 2000 to see if it helps.
As said however it is best to properly shield and ground wires rather than using software to mask the problem.
Hood

[ALR]

Thanks Hood,  The problem is mechanical vibration in one of the limit switches.  I felt a lot of vibration in the Y axis switch and loosened the screw holding it in place and the problem went away.  I tried a debounce interval of upto 3000 and it still tripped.  I am going to have to find a way to isolate the vibraiton from the router. 

One other problem I noticed is that the machine's soft limits have moved.  About have way through the roadrunner program the tool path seems to have shifted about an inch.  Could this also be associated with the mechanical vibration or could it be from electrical noise.

ALR

[ASC]

the moving soft limits seems to indicate that the machine wasn't homed properly.  In regards to electrical noise, placing a small capacitor between the offending signal and signal ground works wonders in reducing noise.