RDC6445 Install Question

Hi All-

I’ve retrofitted a Full Spectrum laser with the RDC6445 because the Full Spectrum controller is, quite honestly, useless for production/professional type work. Everything is now functioning correctly and working well however I have one little snag that I could use the community’s help with:

Home is top right corner of the machine. When I reset the axes the machine will head this direction. Pressing up arrow causes Y to move up, pressing right arrow causes X to move right. Incremental positioning decreases as the laser moves toward home. Everything makes total sense and works correctly, BUT…

The limit switches (located top/right) only activate when the motors are moving AWAY from them. I don’t understand why! I’ve gone through all the settings and can’t figure out a way to trick the machine to enable the limit switches to function when the machine is moving toward them. Obviously this means when the machine hits the home position the switches don’t cut and the machine crashes. What on earth is going on and how do I program this correctly?


What are you looking at when you decide they’re “active”?

Are they Normally Open switches or Normally Closed switches?

Do they have open-collector / open-drain (“NPN”) outputs or something else?

It’s most likely caused by having the wrong Limiter polarity or Spacing polarity (the translations vary) for the switches. Flip that for both of them and see if that improves the situation.

@ednisley is probably right here…

You can watch the controllers led and see when the switches are active. This is a simple hardware check.

Here’s a poor video example, but it shows how you can test them yourself…

That is the input, you can go to Z/U → Diagnosis and observe what the Ruida is reading… might have to press enter to have it read the inputs again.

You can also press esc on the machine console and it will abort the home function and allow you to take control without excessive head bashing…

Good luck


You guys will laugh, it was a simple fix. I had the limit switch plugged into the X+ Y+ but needed X-/Y-. DOH!

Now onto configuring the laser itself. I have a Reci 150w C6 laser tube wired for high-level signal and set for 20khz frequency, but it’s running horribly. When testing the pattern directly at the filter on the end of the laser tube, I don’t even produce a solid circular burn mark at 30% power. hmmm, any ideas?

The + inputs are for limit switches… :wink:

When a Ruida boots and attempts to home, it only looks for the home (-) inputs… After it completes the home, it will then monitor the limit (+) inputs and ignore the home (-) inputs.

  1. properly working tube
  2. clean and aligned optics
  3. proper focus

If you have these three they work… Best place to start is the beginning, so check that the tube is in TEM00 resonance or mode

This is done at m1 on a test target. I test mine like this…

If the tube isn’t in TEM00 mode, it will never align properly and won’t work like it should…

Generally with an older tube, you can figure it’s the tube, but it can be an lps… You can get new tubes that fail this. From what vendor did you acquire the RECI tube?

When they manufacture tubes, the mirrors and other parts alignment is critical. When one of the tubes fail to test to specifications they generally don’t toss it… They sell it to vendors who put them in machines they sell or sell the tube at a better price than the manufacturer…

When you pulse this, make a very light mark. You want to see the Gaussian power distribution across the beam. You can’t tell much from a hole or a black spot. This is mine when I found it was not in TEM00 mode… This was dead center, three days later this is how it changed.

If you are in TEM00 then you need to properly clean, align and ensure proper focus.

Let us know what’s going on…

Good luck


Thank you! This is great information. The following laser image was taken directly at the end of the laser tube on the first filter. 20Khz, high-signal, 30% power, 150w laser. To me this can’t mean much less than a burned out laser. The tube is a Reci C6 from Full Spectrum.

This should be a round burn the size of the output beam…

The Gaussian power distribution should is represented like this…


Since we are looking at in from the Z direction… this is more like what you should be getting…


Dark in the center getting lighter as the beam power decreases.

It should be round or it can’t have this power distribution.

Is this a new tube?


No, it is about one to two years old but I don’t know how many hours. It hasnt been performing well for a bit but not this bad. I was looking at the cloudray replacement laser for $1500. Its a reci W series.

Is there a way to conclusively determine the laser tube is shot beyond the test I’ve performed? Or could it be the power supply?

Generally it’s the tube… it’s the consumable.

However I’ve heard of laser power supply (lps) being replaced and fixing the issue. Never actually seen it, but there isn’t any reason to assume they were not telling the truth…

Do you have good cooling, did you run it hard?

Most RECI tubes have a 10,000 hour rating.

There isn’t any way I know of to test what is failing other than replacement.

In your case which is lower cost?

I’d tend to go towards the tube, but you have to live with your decision most of this stuff isn’t returnable.

I not only have a mA meter, but also a kV meter on the anode. I had a tube fail and the hv didn’t change. I don’t know how you could test it without the proper equipment that none of us have…

Do you have a mA meter and has it been normal?


I do have an ampmeter on it, its only pulling about 28ma at 100% power. Doesnt seem right

Anything over 100W is around 28mA, so it sounds OK…

Do you run it here a lot?

Since this is probably correct and the current wouldn’t be up there without the DC excitation voltage being OK…

I would still tend to point my finger at the tube…


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Is there a particular reason you’ve wired this for high-level signal? I actually don’t know how that would be configured on the Ruida but it’s certainly unconventional. From what I’ve seen, typical Chinese lasers are all active low.

I wouldn’t anticipate this by itself being the cause of your issues but I’m curious how the Ruida is configured to handle this as I thought it was hard-wired for active low.

You can change laser enable (invert it) within the Ruida controller…

The lps has an H input for active high laser enable controllers.



Thank you for that. I figured there would be a configuration for that but couldn’t find one in the documentation.

Does the PWM frequency have any effect on laser health or quality? It’s currently set for 20khz, my understanding is adjusting this is really only useful for rendering images well, something we don’t do often with our laser.

Technically pwm is frequency indenpendant and what many call the base frequency is termed the period…

With a 1kHz base frequency the period is 0.1mS. With a 20kHz signal it’s 50uS… it’s simply 1/frequency…

The lps has an input low pass filter, so it can’t do much in the way of changing what’s going on…

With dsp controllers the pwm (or analog control voltage) is feed into the IN terminals of the lps… This produces a control voltage within the lps that regulates tube current. Most of these also produce an analog output control voltage.

The K40 interface is a bit different, if you work on one or it’ grbl based.

So in simple terms you won’t see much difference…

Since these have to be compatible with analog DC control signals… I can’t see where it would really matter in the end.