2.x Laser Build, LPS output will not turn off after the cmd to turn on is sent.

Hello,

This is regarding a non-standard 2.x Linux CNC build using a real time BOB.

I just upgraded my 3 year old home built laser with a new 130watt tube and power supply. My old system used low level PWM control but I decided to switch to high level during the upgrade (always wanted to make it fail safe to avoid flashing the laser if the system was not started in proper order).

I removed the "invert" command from the laser fire pin in the .hal file and adjusted the max PWM output to correspond with the max safe level for the new tube.

The laser fires great (turned a fired brick into glass), everything is working well - except after the fire comand (M3 or M4, tried both) in any gcode file is run the laser power supply does not go into standby - including when using the test fire option within 2.x GUI (146.ngc) it just keeps firing. Thankfully I have a emergency "laser off" switch that interrupts the coolant verification signal and shuts it down properly.

I worked on this all day, I tried everything I could think of but have not figured it out yet. I don't have a good o-scope to check the BOB signal with, so I don't think there is a way to eliminate the possibility of a hardware or wiring issue?

I think it must be in the 2.x laser .hal file but I cannot find it.
The only other option is that the new power supply has a grounding issue that is allowing some stray voltage to trigger the laser but this would be odd since the laser power level is consistent at my 25mA set point.

Any ideas?

Hi Andy,

I have attached the .hal file, a test fire file created by my dxf-gcode converter and the 2.x laser test fire file 146.ngc

I don't know how I did not see it before but the "Power" bar indicator on the right hand side of the 2.x laser screen comes on and stays on whenever a gcode file is run - any file. I use PWM (or PDM) - not "Power" and the PWM bar and indicators on the 2.x screen do fire properly per the gcode files. This is the problem but I cannot figure out where the "Power" command is being issued from.



Thanks,
Travis

Thank you Andy, that led me in the right direction. It is pin 7 and we have reconfigured the .hal file accordingly - updated attached along with .ini. I still need to adjust my gcode converter. I am getting a low level signal (results in 5mA) at all times (even before running a file) with the new configuration, it is just enough to start the tube, any idea how to adjust the low level signal out? I thought I was already at 0.0 in .hal, am I not? I am reading 1.31vdc on pin 7 when idle. After running a file the LPS remains on at about 15mA - although this could easily be the gcode test file which still needs to be reconfigured.

The 1.31vdc is a wiring issue - it is present even without emc running. I imagine it has always been their and I never knew - since I had been using a low level trigger. I am working on it.

Most of the stray voltage is coming in over the parallel port cable - strange since my BOB (V_5 from LightObject) is supposed to be optically isolated. The parallel port cable shield does not test common with the PC or with the any of the CNC DC-. I tried grounding out the shield to eliminate the possibility of inductive current from the bundle of cables but it had no effect. In the hope of using a shortcut I also tried switching back to low level pwm, but it still triggers the laser (at 18mA this time) - proving that this is likely a new problem. I have not made any significant wiring changes with the new power supply - I did switch from a 110vac LPS to a 220vac LPS - for increased stability with the higher wattage laser and I changed out the coolant flow switch for a new one while adding a PID temp controlled relay in series with the coolant flow switch - for a coolant flow and high temp failsafe.

I am considering adding a jumper from my DC Negative buss to AC Earth Ground, I stopped short of doing this when I first built the laser because I did not want to create a earth ground path through the DC circuits in case of a high voltage leak from the LPS - no need to blow everything up, especially since the LPS, DC supply cases and whole machine case are earth grounded. Is this flawed logic? I tried a temporary jumper with the LPS disconnected with no change on pin 7.

I think I am back to the .hal setup at this point and trying to lower the minimum voltage on pin 7. Any ideas?

I have an ancient heathkit with crt display (mad scientest special), but I don't think it works anymore and I doubt I could remember how to operate it.

I do have a 40kHz meter on my fluke multimeter. I just checked pin 7 to LPS DC ground. With emc in standby (or off) the fluke reads OL (overload). with the test file running the fluke reads 11.06kHz.