Hi, After a failed experience with an Xpro V5 controller on my QB Pro I decided to aquire a BlackBox which is on its way to me as I'm writing this. Following best practices, and what makes the most sense to me, I setup the xPro homing switches in a NC configuration, which worked just fine. Now, with the new unit I want to incorporate end run switches on all axes. The thing is that in my reaserch (including threads in this very same forum) I have found mostly indications on how to wire them NO in parallel on arduino uno boards (I do know that BB is based on them). I'd really prefer to have a NC configuration. Since my xpro fault is related to an axis driver, I used it to test the suggested wiring. I've set GRBL $5 accordingly for NC and NO for each test and I'm using the UGCS console's verbose output to verify the alarm status. The thing is that I could not make NC work in parallel, nor in series. NO did work in series (I did not test NO in parallel) I'm attaching a picture of the latter wiring for reference Does anyone know if it's at all possible to have all 6 limit switches in a NC configuration with the BlackBox? Assistance greatly appreciated Gonzalo
1) get yourself the proper Xtension switches Xtension Limit Switch Kit 2) Wire up 6x as shown in the table below the diagram on docs:blackbox:connect-xtension-limit [OpenBuilds Documentation] Unfiltered switches near a VFD spindle is a nightmare for EMI issues - while we can tell you how to wire it - it really ain't worth it in this application
Thanks Peter. I already have switches (regular ones), which at least for the purpose of homing, have worked fine so far, without any false triggering (I run them @24v, which I plan to replicate with the BB controller). The +3 months that my machine has been out of commission (plus the couple hundred hours spent troubleshooting it) has put such a financial burden on my business that I simply cannot afford spending any more money on it, at least for a while. As I mentioned, I haven't faced issues with my 2.2 kW VFD spindle interfering with the switches so far. Maybe I will face issues once all 6 of them are active as end runs, for granted you have way more experience than I have in this matter. But I'd like to take my chances. If it turns out it doesn't work, I'll stick to just 3 homing switches, and leave the improvement for later. So I'd really appreciate if you can share the NC wiring with me
Loop GND to C on first switch NC on first switch to C on 2nd switch NC on 2nd switch back to SIG Set$5=1 Use Troubleshooting tab in CONTROL to Test Please elaborate on what you are planning here - as it may cause damage. BlackBox already has built in pull-ups
Thanks Peter. Just to be clear, when you say "loop", you mean to bridge them? Regarding your question. I mean setting the corresponding jumper to run the switches at 24v, to minimize interference. Plus, I hope to move to proximity sensors in the future and they typically operate at higher voltage than 5v. Speaking of which: Does this wiring work for proximity sensors too (SN 04 - N2)? Please let me know if I explained myself
NC wiring is a loop from SIG to GND with one or more switches inline (C and NC terminals) Then you need powered Switches like the Xtension Limits It has no effect on bare switches like these - Xtension Limits has active filtering circuitry powered by the limits-v rail Yes, and yes on the 24v jumper for that.
Thanks again Peter. I have just received my BlackBox I'm trying to identify the terminals on the micro switches as per your instructions though. Typically, on regular switches, the terminals are labeled NC - NO - C, in that order. From your explanation I gather: NC = GND NO = V+ C = SIG So the suggested wiring would be like this: [EDIT: Removed to avoid confusion. Correct wiring in Peter's post bellow] is this correct?
NO! Please don't connect V+ to basic switches like this! Remember wiring mistakes will void your warranty. See Section 3.4 of docs:blackbox:start [OpenBuilds Documentation] If you look at the Micro Limits page (Section 3.4.2) you'll notice in the "IMPORTANT WARNING" section we clearly say to use 2-conductor wire only. SIG and GND. No V+ for this type of switch!!! Also in this thread I already advised you not to, when you first mentioned 24v: and also If you don't have powered switches (like Xtensions or Inductives) you cannot provide power to them its just not how a simple switch works! If you do insist on NC, do it like this (see the loop) Again: NOTHING connected to V+!
Thanks Peter. Dully noted that the 3rd terminal (NO in this case) does not equal V+. As per your instructions I'll keep the jumper on 5 volts. Anyway, I never intended to connect anything to V+, the diagram that I attached does not use V+ at all. I'm indeed using only 2 wire cable. The diagram for micro switches in the documentation does not cover end runs, so yours is appreciated. I'm going to remove my diagram from my post so not to confuse other people.
Most people use homing+soft limits - better to prevent a crash move, than running away, ruin the workpiece, and finally end up maybe hitting an endstop. If you don't trust your machine to follow gcode correctly, then adding switches is a band-aid for some other bigger problem (bad stepper drivers / bad mechanicals / untuned parameters) which causes the unreliable runaways in the first place
Hi Peter, I have 2 questions regarding NO - NC just for my education. I'd like to better understand the reasoning. To not open new threads, I'll post them here. 1) Why BlackBox defaults to NO, when best practices indicate NC? 2) Controllers like the Xpro v5 have different firmwares in case you opt for NO or NC. But in GRBL you can opt between these two with the $5 command. How these firmwares relate to GRBL? In other words, What if I load a NO firmware and then configure GRBL as NC? Can you please shed some light to this?
Ease of use plus we threw in a lot of active filtering circuitry that the cheap controllers doesn't have (NC is a quick way for them to avoid adding decent filtering. BB and Xtensions has three layers of filtering and one layer of opto coupling) 2) not sure about firmwares, but all Grbl firmwares has the $5 setting
The option for NO or NC firmware for the XproV5 refers to the door switch setting - $5 works fine with either version of the firmware. Alex.
Thanks both. Peter, the reasoning for NC being a good practice that Ive come across, that actually makes a lot of sense to me is that whenever there's a cut wire or something disconnects inadvertently, the machine alarms.
