# Relay Interference **URL:** \ **Category:** General Guidance\ **Created:** [June 19, 2024, 3:39pm UTC](https://forum.arduino.cc/t/relay-interference/1273411 "2024-06-19T15:39:57Z")\ **Posts on this page:** 17\ **Page:** 1
**Author:** ![robhoski007](https://avatars.discourse-cdn.com/v4/letter/r/b2d939/32.png) [@robhoski007](https://forum.arduino.cc/u/robhoski007)\ **Post date:** [June 19, 2024, 3:39pm UTC](https://forum.arduino.cc/t/relay-interference/1273411/1 "2024-06-19T15:39:57Z")
Hello, I'm hoping someone can give me some advice on a situation I'm having with an Arduino type card. The card is an MKS DLC 32 version 2.1. I'm using it to control a CNC plasma cutter that I built. If the plasma cutter is not turned on the g-code will execute its movements without issue. I originally thought the problem was my high frequency pilot arc machine and so I replaced it with a blowback machine which is supposed to be much more friendly to sensitive electronics such as the control board I'm using. However, even after I replaced the plasma cutter I still have the issue. It dawned on me to consider the fact that I had the small opto-isolated relay that activates the two pin trigger switch on the plasma cutter next to the control board. This meant I ran the two trigger wires from the machine into my control board box where I connected them to the relay. I recently read that relays can also cause interference and decide to move the relay from the control board box to a location near the plasma cutter some ten feet away. When I first ordered relays I ordered three of the cheap little red-board relays commonly found on eBay or Amazon. All three have failed now and I am waiting for new ones to arrive. The relays are 24 volt and run from the 12/24 volt power supplied by the control board. A 5v signal wire from the control board activates the relay to close the business end of the switch which triggers the plasma torch. I'm hoping when the new relay arrives that having relocated it away from the control board will make a difference. Does anyone feel that this may have been my trouble all along? ---
**Author:** ![zwieblum](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/zwieblum/32/427702_2.png) [@zwieblum](https://forum.arduino.cc/u/zwieblum)\ **Post date:** [June 19, 2024, 4:35pm UTC](https://forum.arduino.cc/t/relay-interference/1273411/2 "2024-06-19T16:35:33Z")
Can you describe your problem in less than 50 words please? ---
**Author:** ![kmin](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/kmin/32/1147370_2.png) [@kmin](https://forum.arduino.cc/u/kmin)\ **Post date:** [June 19, 2024, 4:40pm UTC](https://forum.arduino.cc/t/relay-interference/1273411/3 "2024-06-19T16:40:00Z")
Relay doesn't make interferences except when it's switching. You need to be specific with your issue, what happens and when? ---
**Author:** ![robhoski007](https://avatars.discourse-cdn.com/v4/letter/r/b2d939/32.png) [@robhoski007](https://forum.arduino.cc/u/robhoski007)\ **Post date:** [June 19, 2024, 6:36pm UTC](https://forum.arduino.cc/t/relay-interference/1273411/4 "2024-06-19T18:36:34Z")
Plasma cutters do switch on and off frequently when they're cutting out a design. Which means the relay is turning on and off frequently. After about 6 to 8 switching cycles I get an error code that says port closed and the machine stalls sometimes with the torch on sometimes with it off. ---
**Author:** ![robhoski007](https://avatars.discourse-cdn.com/v4/letter/r/b2d939/32.png) [@robhoski007](https://forum.arduino.cc/u/robhoski007)\ **Post date:** [June 19, 2024, 6:40pm UTC](https://forum.arduino.cc/t/relay-interference/1273411/5 "2024-06-19T18:40:01Z")
I guarantee if I described it in 50 words or less people would suggest all the things that I've already tried. ---
**Author:** ![kmin](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/kmin/32/1147370_2.png) [@kmin](https://forum.arduino.cc/u/kmin)\ **Post date:** [June 19, 2024, 6:48pm UTC](https://forum.arduino.cc/t/relay-interference/1273411/6 "2024-06-19T18:48:51Z")
> [@robhoski007](#): > > I guarantee if I described it in 50 words or less ..but you didn't describe the problem... > [@robhoski007](#): > > I get an error code that says port closed What does it mean? From where? ---
**Author:** ![zwieblum](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/zwieblum/32/427702_2.png) [@zwieblum](https://forum.arduino.cc/u/zwieblum)\ **Post date:** [June 19, 2024, 7:43pm UTC](https://forum.arduino.cc/t/relay-interference/1273411/7 "2024-06-19T19:43:10Z")
My cristall ball say GRBL + UCS or some of these combinations. Which translates to non-existing EMC shielding --\> plasma turns on chances are the arduino goes haywire. ---
**Author:** ![kmin](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/kmin/32/1147370_2.png) [@kmin](https://forum.arduino.cc/u/kmin)\ **Post date:** [June 19, 2024, 7:54pm UTC](https://forum.arduino.cc/t/relay-interference/1273411/8 "2024-06-19T19:54:50Z")
I could imagine exactly that even if my cristall ball is out of service at the moment. ---
**Author:** ![robhoski007](https://avatars.discourse-cdn.com/v4/letter/r/b2d939/32.png) [@robhoski007](https://forum.arduino.cc/u/robhoski007)\ **Post date:** [June 19, 2024, 8:42pm UTC](https://forum.arduino.cc/t/relay-interference/1273411/9 "2024-06-19T20:42:48Z")
The machine will stall out after about 6 or cuts as it tries to execute the cutouts of the pattern. I originally thought it was the high frequency plasma ark but I replaced my machine with a blowback cutter. Here's what they say about a blowback start plasma cutter. With blowback torches, before the trigger is pulled, the electrode and the grounded part of the torch are in contact. When the trigger is pulled the machine turns on the air flow while turning on the regular welding cutting voltage. The airflow causes the electrode to blow back out of contact, striking the arc. Since this method uses no high voltage or high frequency it creates next to no EM interference and is ideal for CNC applications. ---
**Author:** ![kmin](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/kmin/32/1147370_2.png) [@kmin](https://forum.arduino.cc/u/kmin)\ **Post date:** [June 19, 2024, 9:13pm UTC](https://forum.arduino.cc/t/relay-interference/1273411/10 "2024-06-19T21:13:29Z")
> [@robhoski007](#): > > The machine will stall out after about 6 or cuts as it tries to execute the cutouts What happens around 6. cut? Interferences can cause wild things, but it's important to understand if there is specific pattern. "Stall out" what does it mean to you? ---
**Author:** ![robhoski007](https://avatars.discourse-cdn.com/v4/letter/r/b2d939/32.png) [@robhoski007](https://forum.arduino.cc/u/robhoski007)\ **Post date:** [June 19, 2024, 9:51pm UTC](https://forum.arduino.cc/t/relay-interference/1273411/11 "2024-06-19T21:51:56Z")
The control board loses connection to the computer and the CNC machine stops moving the torch. The job log on open builds control states port closed. ---
**Author:** ![kmin](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/kmin/32/1147370_2.png) [@kmin](https://forum.arduino.cc/u/kmin)\ **Post date:** [June 19, 2024, 10:32pm UTC](https://forum.arduino.cc/t/relay-interference/1273411/12 "2024-06-19T22:32:36Z")
I have built quite big CNC machine and I can immagine different cases. Random misbehavior would indicate interferences in signal wires. If there is pattern, it could be interference or power issue, maybe even error in code. > [@robhoski007](#): > > The job log on open builds control states port closed I don't know what that means. Some switch triggering? Try to observe the mechanism of your issue. ---
**Author:** ![robhoski007](https://avatars.discourse-cdn.com/v4/letter/r/b2d939/32.png) [@robhoski007](https://forum.arduino.cc/u/robhoski007)\ **Post date:** [June 20, 2024, 12:04am UTC](https://forum.arduino.cc/t/relay-interference/1273411/13 "2024-06-20T00:04:04Z")
I was thinking if it was a code issue then it should happen all the time. But it only happens when the plasma machine is turned on. I'm hoping it was an interference issue with the cheap relay that was next to the control board. I took many steps to shield the electronics behind metal plates, running ground wires, adding a USB isolator, etc. and still got the problem. The only thing I haven't tried is relocating the relay. It's the only thing I can think of that might be causing interference with the board. I'll know in a couple days when the new relays come in. Thanks for your advice. ---
**Author:** ![zwieblum](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/zwieblum/32/427702_2.png) [@zwieblum](https://forum.arduino.cc/u/zwieblum)\ **Post date:** [June 20, 2024, 6:53am UTC](https://forum.arduino.cc/t/relay-interference/1273411/14 "2024-06-20T06:53:44Z")
We still have not seen a picture of your installation an wiring. ---
**Author:** ![johnerrington](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/johnerrington/32/340106_2.png) [@johnerrington](https://forum.arduino.cc/u/johnerrington)\ **Post date:** [June 20, 2024, 8:21am UTC](https://forum.arduino.cc/t/relay-interference/1273411/15 "2024-06-20T08:21:11Z")
I think we now need a schematic. > [@How to make a schematic you can post.](https://forum.arduino.cc/t/how-to-make-a-schematic-you-can-post/675103): > > When you submit a question on the forum you will usually need to add a schematic (circuit diagram). The tutorial that follows will explain some ways to create a useful image; however lets start by explaining how to add the image to your post. Its easy. Having created the image all you need to do is : Save the image somewhere convenient - maybe your desktop Start your post, and place the cursor (insertion point) where you want the image to be shown; [upload image to forum] 3: click th… Also I'd strongly suspect a grounding issue. Have you kept the high current gounds seperate as shown here? > **[skillbank: Experiments and projects with an Arduino microcontroller](https://www.skillbank.co.uk/arduino/grounds.htm)** > > Ground connections for Arduino and related modules ---
**Author:** ![TomGeorge](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/tomgeorge/32/215261_2.png) [@TomGeorge](https://forum.arduino.cc/u/TomGeorge)\ **Post date:** [June 20, 2024, 9:39am UTC](https://forum.arduino.cc/t/relay-interference/1273411/16 "2024-06-20T09:39:19Z")
Hi, @robhoski007 Welcome to the forum. > [@zwieblum](#): > > We still have not seen a picture of your installation an wiring. Or a schematic. Can you please post a copy of your circuit, a picture of a hand drawn circuit in jpg, png? Hand drawn and photographed is perfectly acceptable. Please include ALL hardware, power supplies, component names and pin labels. Thanks.. Tom.. πŸ˜ƒ πŸ‘ β˜• πŸ‡¦πŸ‡Ί ---
**Author:** ![system](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/system/32/1140315_2.png) [@system](https://forum.arduino.cc/u/system)\ **Post date:** [December 17, 2024, 9:40am UTC](https://forum.arduino.cc/t/relay-interference/1273411/17 "2024-12-17T09:40:12Z")
Closed on December 17, 2024, 9:40am UTC This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.