stepper driver and DSP setup

[ljd10]

can anybody tell me if the DSP board accepts or uses step & direction signals?
Where between board software and board do you enter the parimeters as far as steps per revolution or distance per reveolution? my understanding is once that information is input-- the board should have the basic movement figured out. i havent' been able to find any of that information anywhere. the rest of it is laser power through pwm and tube cooling, limit switches. I read alot about speed. How about servo Motors that except step and direction control? I would think that the pwm laser power control would be a bigger issue then motor speed. anyway just starting out on this project I will accept as much help as I can get.
thankyou from a new member.

[baccus61]

Hi LJD10

The DSP's act sort of like a printer driver in that you send the information to the DSP from the drawing program (Corel, AutoCad) and then the DSP processes the information into a form that is sent to the controllers.
This is the Step and Dir signals and the PWM.
To my knowledge most laser controllers DON'T use G-Code to process their files. ( probably because the file sizes would be way to big for what it has to do ).

The Laser is turned on where there is a black dot and turned off where there is a white dot. Some controllers even modulate the beam using gray scale for the laser power which is modulated by the controller then sent to the laser power supply in the form of a square wave.

Mach3 uses G-Code for a limited uses of a laser but it only does Vector cutting well and raster engraving is still a way of for anything noteworthy.

The size of your machine is set up in the software as is the steps per mm of travel for each axis.
You can download a manual here on this forum that will show you how to get everything set up but it is a bit hard to understand if you haven't got a laser in front of you to show you what is happening when you change a particular setting.

Speed AND power make a difference with any laser. Lets just say for instance you have a 1000 Watt laser pulsing at full power and a speed of, say, 12 meters a sec and it will burn the same size spot and depth as, say, a 30 watt laser pulsing at 1/2 power and 1mm sec. (figures made up out of my head just to make a point).

The laser needs time to turn on and off so really fast speeds are not going to get you where you want to go unless you set up your laser to use the speeds that it is rated for. A glass tube laser has a rise and fall time for lasing a bit longer than a RF one so it's speeds won't be the same. Like turning on a Fluoro light in your house.

Some Servo motors use the Step and Dir signals and are compatible with the DSP's. Yaskawa make a model you could use. Look for the "P" in the serial number. It stands for "Pulse"
If you had a Yaskawa SGM-04A314P then the SGM is the model number and the 04 is for 400 watt. The A is for 240 volt (B is for 110 volt) and the 314 is different specifications like shaft keyway or encoder pulses etc and then last but not least the P is for a PULSED unit that can take the step and direction signals.

I hope this has shed a bit of light on the subject for you.
regards
Richard.

[ljd10]

yes its a major start in understanding. for clarification purposes I am building a laser from scratch. I need to start assembly on it. I have the dsp board on its way. haven't seen it yet. the laser tube and power supply are here. I also need to know if acrylic sheets can act as safety windows. I do have stepper motor and servo motors. I do have stepper drivers and servo drivers that use step and direction (gecko drives.) I also have Mach3 and thats why the dsp.
I am fairly familiar with cnc operations-built a couple for hobby. But this laser is totaly new ball game.
thankyou for your help and patience.--I will take all I can get.

[baccus61]

Hi Ljd10
Acrylic absorbs 100% of the CO2 wavelength so it will be OK for a safety screen. Polycarbonate also absorbs it as well so any cheap poly glasses will work as safety lenses.
I read of a person who has black spots on his retina from a red 1Watt laser pointer being reflected off white paper and he was wearing safety protection. It would have been alright if it was infrared wavelength but the 625 red diode wavelength passes right through polycarbonate and acrylic so there is no protection.
I don't think the DSP will work with Mach3. It integrates into the software of Corel or AutoCad and you send the screen contents to the driver.
To my knowledge I haven't seen anyone hook up a DSP to Mach3 but I might be wrong.
Rich.

[ljd10]

thankyou for a very important piece of information. (acrylic). yes- I dismissed the mach3 idea in favor of the dsp- looking forward to see it in action.
thankyou!