Have just purchased an Opto board to try and eliminate EMI in my system, which has not yet arrived. I am currently using the Black Box controller but my Limit switches are connected with unshielded wire and I am getting the occasional 'hiccup' in the system due, I think, to EMI being generated by induced currents via the Limit switch wiring. This is the kind of board I want to add:- Although it looks simple, I'm not too sure where exactly the connctions hook up to on the Openbuilds Black Box, but I do know that I must have a separate 5v Supply and Ground for both 'sides' of the opto isolation board isolator. Has anybody actually installed one of these types of board - and I know they are many - and if so, could they point me in the right direction, particularly with a diagram showing what wiring goes where on the Black Box? I would apreciate it greatly if someone could help me out with this as it is the only problem I have had with my Black Box. I have installed caps on all my limit switches (which helped a lot), but I am still getting the odd occasion when something interferes and causes the machine to lose position. Many thanks in advance...
5v to any V+ (set Limit Voltage jumper to 5V NBNBNB) on any of the limit connectors GND to any of the limits connectors GND SIG on each limit to its relevant XY or Z pin on your board. Then play with $5 till it works in Grbl Settings. Sounds like you have regular switches, we recommend Xtension Limits
Hi Peter, To make things a little easier, I have updated my picture of the board I intend to use. Afrer all, they say a picture is worth a thousand words and it may just make it a little easier for others? Many years ago, I used to be a Technical Author, and I just like to make things clear! Willow52
Peter, just to let you know that said buffer is now installed and is working perfectly - not a single glitch or hiccup since the install. Just wish I had installed it earlier, would have solved a whole heap of problems I have had with noise in the system. Once again, many thanks for all your invaluable help.... Regards, Willow52
Hi Peter, may I use my type of opto board also to reduce EMI in my CNC Plasma System? I am using the shown NPN normally open as limit switches and as soon as the plasma torch starts I get error 9 from control software. Black box is set to 5V. I would attach the right side of the opto board to the black box like you guys have shown in this discussion. The blue cable as GND and brown cable as V+ of each limit switch would be connected to the left side of the opto board. My question is where to connect the black cable of the limit switch? Thank you. Kind regards Leo
Then yes, you can use yours. Also consider a LF plasma, easier than shielding everything. HF start plasmas are for habd cutting
regarding wiring to opto board > The blue cable as GND and brown cable as V+ of each limit switch would be connected to the left side of the opto board. My question is where to connect the black cable of the limit switch? thx
Using inductives? Have you tested them directly to the BB yet? They are pretty noise immune by themselves
yes, I have shielded all cables but still have problems with error 9. Plasma cutting with runed off limit switches is possible. As soon as I activate them in the software, I have this issue. So I ordered the opto board and will try it again. I just dont know if and where the black cable of limit switch has to be connected. All cables are shielded and I have ferrite cores on each end of each connection. Its a pain in the butt Thx
Refer the switches wiring sticker or documentation. Again though, you might still not have luck even with optos. Every wire is an antenna. They all bring noise into the controller, the power rails, etc. Getting rid of the noise source is best. Craiglist the HF inverter off to a welder guy, and order a Cut50L (blowback start) - probably spent more on workarounds already (; - if not, you will. Later on, when EMI keeps ruining jobs and wasting materials.
ok Peter, I give up with all the shielding and opto boards stuff and will purchase a blowback start type plasma.... thank you Sir.
You won't regret it. If you are serious about building a plasma machine, its worth not dealing with bottom end HF inverters
