Very strange interference issue happening with my monport 80w co2 laser. I recently installed an external air compressor with a 24v solenoid. It it wired into the same relay the controlled the built in air compressor the machine came with. The KT332N controller output is wired to relay coil and relay controls the solenoid that I added. However, randomly in the middle of cutting, the controller will say xy resetting and laser returns to the home position. And then prompts me to continue the job, it will move out and continue cutting for a couple of seconds and then the xy will reset again and moves the laser to home position. If I disable air assist, the issue goes away completely. Do I need to move the solenoid cable away from other wiring or swap to shielded cable? This issue is very annoying and have yet to find anyone else talking about it online at all.
The KT332N manual says:
OC output, the maximum driving capacity is 300mA
That is barely adequate for most 24 V mechanical relays and requires a flyback diode.
Mechanical relays typically have an input coil power rating, rather than a current rating. The KT332N current limit could, in principle, handle up to 7 W = 24 V × 0.3 A, but that ignores the transient current while moving the armature.
What is the relay coil’s input spec?
Does the relay include an internal diode or have you added a diode across the relay input?
Rather than bother with all that, I highly recommend using a DC-to-AC solid state relay along these lines:
However, the problem is most likely due to compressor motor transients glitching the AC power line when it turns on to refill the air tank. If it’s on the same circuit breaker / outlet as the laser, then that’s almost certainly what’s happening.
Another likely problem is the 24 VDC supply is grossly under-rated for the actual load in the machine. They tend to fail early and produce baffling symptoms on the way out, so it may be the compressor is producing enough of a power line glitch to brown-out & reset the controller.
If powering the compressor from a different breaker and using an SSR instead of a mechanical relay doesn’t solve the problem, then suspicion falls on the 24 VDC power supply.
I have moved the compressor to an isolated circuit and still have the issue. The relay I am referring to, came with the machine from the factory, and has no issue turning the oem air compressor on and off. I will have to look where the relay is gettings its 24v from but I would guess its coming right off of the oem power supply.
And so if I swapped to a SSR, then I would need to get a different solenoid that is for 24 AC correct ?
Also I could try just bypassing the relay completely. I have seen it done on other lasers before. Solenoid coil is only 4.8W, which should only draw 200mA.
Bypassing the relay and running direct from KT controller to solenoid, works perfectly now. I’m guessing Monport thought relay was needed for integrated air compressor. Thank you for your detailed response.
Reasonable people disagree on this.
IMO, putting an SSR between the controller and whatever it’s driving means when something horrible happens, it destroys ten bucks of SSR rather than four hundred bucks of Ruida controller.
Horrible things don’t always happen, but …
I have a dc/dc one on order.
I’ve been running an advanced air assist, directly from my 6442g, for almost 5 years with no issues. The solenoids I purchased draw about 180mA, so well within the capable range of the Ruida. Even if you choose the 300mA maximum in some manuals, compared to the manual stating 500mA maximum.
Dose your machine turn the air off and on with the laser or for the entire layer? There is a setting available via RDWorks that changes how it blows. On for the entire layer or only when it’s lasing. If this is occurring in the middle of a layer, I’d check this. There is no reason it should reset mid layer if the solenoid isn’t cycling.
I put these together like the manufacturer specifies, directly driving a solenoid. I think they would know since they are all over China.
If you want to add them that’s up to you. I think it’s possible that you might have another issue masking this result.
I have never had my machine complain about resetting the axes.
These controllers are pretty tough, although I did loose my water protect input.
The problem disappeared after I bypassed the relay and ran direct to controller. But yes, when it was having issues its because its toggling the solenoid every time the laser starts and stops a cut path. It would be nice if it would just leave it on for the whole layer like you mentioned. I will have to look in lightburn for a similar setting to the one you describe in rdworks.
Edit: Looks like I can change it in the machine settings through lightburn to enable for whole layer, rather than toggling every individual cut.
If I recall, there is a blow option in RDWorks where you can change this to work with the layer. I don’t know how to change it via Lightburn. Mine was never configured otherwise.
If anyone knows, please pass the word 