by ArtF » Mon Apr 04, 2016 3:27 pm
Hi Glen:
The way I have it set up, Axis 8 controls the PWM, you dont use its step or dir, but the PWM pin selected by the script. PWM#2 in my case. ( Pin 3 of the lcd connector. ).
While the step/dir likely still run on axis 8, ignore them, control is actually that PWM pin.
Now, I don't use any firing logic other than pwm, a pwm of 1% is tickle, so no radiation comes out. This
is typical of RF lasers, there is no fire TTL, just pwm.
Glass lasers, with high voltage supplies are up in the air as to how to control them. There is little
published. I have however, done some reading. At least one manufacturer of high voltage supplies
says to use 20Khz PWM, and leave the TTL input floating. The PWM actually is changed to a
voltage average internally so when it goes to zero, radiation stops. This would make it work the same
as my RF laser does. Turn on time is widely reported to be all over the place, from claims of 10us to
10ms. I believe from testing on my workshop one that its much faster than 10ms, but perhaps it varies..
The hookup with no TTL makes sense, normally the PWM input is simply fed a voltage from the control
board, and the TTL then HAS to control it, but if what Ive read is true, PWM alone is enough.
Let me know how any experiments work out. I can make up a signal control of some sort if it turns
out to be needed, we just need to figure out what IS needed. My RF laser is working awesome, better
than Id hoped, so Im very interested in how you make out. Id set your master PWM on screen to
25% or so, and do an M3 , and see if the laser is happy doing nothing with the 1% minimum,
then see if it triggers when you do a g1 move..
I can give you access to the min and max pwm settings, I haven't added a hook to them yet,
Ive been waiting for a high voltage co2 to hook up so we can figure out the best protocol..
One idea for the TTL is to use it as I use my Laser button on screen, it activates relay #2,
which turns on my power supply, you could instead hook that to give 5 volts to the TTL input
with a pulldown resistor to kill it if you kill the relay. The ideal situation is to be able to
turn it on, have it sit not radiating when still, and have the pwm properly trigger it as it moves..
Art
Hi Glen:
The way I have it set up, Axis 8 controls the PWM, you dont use its step or dir, but the PWM pin selected by the script. PWM#2 in my case. ( Pin 3 of the lcd connector. ).
While the step/dir likely still run on axis 8, ignore them, control is actually that PWM pin.
Now, I don't use any firing logic other than pwm, a pwm of 1% is tickle, so no radiation comes out. This
is typical of RF lasers, there is no fire TTL, just pwm.
Glass lasers, with high voltage supplies are up in the air as to how to control them. There is little
published. I have however, done some reading. At least one manufacturer of high voltage supplies
says to use 20Khz PWM, and leave the TTL input floating. The PWM actually is changed to a
voltage average internally so when it goes to zero, radiation stops. This would make it work the same
as my RF laser does. Turn on time is widely reported to be all over the place, from claims of 10us to
10ms. I believe from testing on my workshop one that its much faster than 10ms, but perhaps it varies..
The hookup with no TTL makes sense, normally the PWM input is simply fed a voltage from the control
board, and the TTL then HAS to control it, but if what Ive read is true, PWM alone is enough.
Let me know how any experiments work out. I can make up a signal control of some sort if it turns
out to be needed, we just need to figure out what IS needed. My RF laser is working awesome, better
than Id hoped, so Im very interested in how you make out. Id set your master PWM on screen to
25% or so, and do an M3 , and see if the laser is happy doing nothing with the 1% minimum,
then see if it triggers when you do a g1 move..
I can give you access to the min and max pwm settings, I haven't added a hook to them yet,
Ive been waiting for a high voltage co2 to hook up so we can figure out the best protocol..
One idea for the TTL is to use it as I use my Laser button on screen, it activates relay #2,
which turns on my power supply, you could instead hook that to give 5 volts to the TTL input
with a pulldown resistor to kill it if you kill the relay. The ideal situation is to be able to
turn it on, have it sit not radiating when still, and have the pwm properly trigger it as it moves..
Art