I'm wondering if I can adapt a RATTM MK100 2.2kw 110V VFD that previously worked with Mach3 and a common (but old) USB breakout board to work with Open Builds Black Box. The previous connections were: INVERT pins on BOB <-----> VFD 10V <------> 10V AV1 <----->AI1 GND <--------> GND OUTPUT pins on USB BOB <----> VFD OUT1<------> X1 (with Omron G2RL-1A-E 12VDC Relay) 12V <-----> COM Here is the manual to the VFD. This is the list of terminals on the VFD: I'm hoping it's as simple as: Open Builds Black Box <----> VFD 0-10V<----> AI1 (Imitated input for RPM Signal) GND<---->GND (Ground) DIR<----->X1 (Input for clockwise rotation) Am I missing anything? Should I remove the relay or leave it?
I made the above connections but the spindle won’t turn on when I send the “Tool On” M3 command from OBC. I do have 0-10v coming out of the Black Box to AI1 on the VFD, and there is a slight pulse of a few millivolts from the DIR pin out of the Black Box, but it won’t trigger the spindle. When I cycle the VFD menu to set it to Keyboard mode with Speed controlled by the potentiometer knob on the VFD, the ”RUN” button functions and the spindle spins. Am I missing something in GRBL settings?
See docs:blackbox:connect-vfd [OpenBuilds Documentation] Most of our writeups jumper the enable (or wire via a safety switch) and then solely uses the 0-10v signal for speed and on/off Requires correct combination of VFD parameters. If your VFD does not have a writeup yet, see the others to note what parameters they change to effect that and cross compare to your VFD manual. Remember to post a writeup for your VFD to help others
Thanks Peter. I was wondering if I can get rid of the DIR signal, since the tool rotation direction is set in the VFD menu. I did go through this one, as the pins look pretty similar to my VFD: H100 VFD 220V with 1.5Kw Spindel 2 poles air cooled with Black Box I'll be glad to post a writeup when I solve it!
Yeah most people don't wire up the DIR signal. Mostly because its a 5v logic signal and many VFDs needs it as a dry contact for the input (See last section of docs:blackbox:jumper-relay [OpenBuilds Documentation] for a workaround way - but not standard. Most VFDs can be set to run off GND+0-10V : 2 wires only) That's usually where people run a jumper wire / switch
PS - Does the Black Box output 5V from the DIR pin when you send the M3 S#### command to turn the tool on? How long does it last?
Yeah understood that: First section takes the 10v from the VFD, and divides it as 0-10v going into AI1 (analog in) - thats the same now except you don't need the 3rd wire as BlackBox generates its own 10v rail Second section, is your enable. That, if you compare our other writeups, is usually where people add a jumper wire or switch Different VFD brand's photo for demonstration purpose:
Thanks Peter. the RATTM doesn't have a FOR terminal, so although I understand the idea of jumpering between X1 and another terminal I'm not quite sure which one. As you said I need to go through others' VFD configurations and see what the equivalent is on mine. I also noticed that there is a jumper pin set between SEL (External power input) and +24V from the previous configuration - I'm not sure what this does either.
Yeah different vendors do things a little differently, but X1-5 are configurable as enabled/fwd/etc Usually a GND Or was this relay on the BOB connecting X1 to 12V? If it worked there, same thing - jumper replaces the relay Also unsure - VFD manual time
I love manuals, especially ones that were auto-translated from Chinese! Thanks so much for all your helpful info Peter. I'll dive into this again after work and hopefully figure it out. Edit - I just noticed that X1 in the RATTM VFD manual says: 3. Voltage range when level input: 9V~30V So if the Black Box is sending 5V, this would be below that threshold. My USB BOB was sending 12V through the relay. I wonder if that is what is inhibiting the spindle from entering RUN mode. So I suppose I could either jumper into this with 10V, or go through the VFD menu and remove the requirement for the input in X1 to RUN?
If the parameters allows, it would be an option to remove the need. If not: Sounds like it could work
I tried jumpering from 10V to X1, but no luck. I read the manual through again and also tried to turn off the input from X1, that didn't work either. I can't find anything that is jumping out at me to change in the VFD settings, so as Peter suggested I need to go through a bunch of other VFD tutorials and see if I can find a clue. If worse comes to worse I can run a job with the VFD in keyboard/potentiometer mode by converting Hz to RPM, but I'd love to get this sorted out.
Is the old Breakout still up and running? What goes into X1 from the BoB? Dry contact connecting COM to X1? (After all relays connect stuff?) | Is that a 12v output pin (as we assumed above), or just labelled 12v? (but maybe is the COM pin of the RELAY with NO connecting to OUT1?) then for us to simulate how it was, jumper X1 to COM?
I was able to reestablish the old BOB with Mach 3. The relay is NO with 18v between X1 and GND. There are 25.5v between x1 and COM. When M3 is sent, the relay closes and X1 drops to 0v.
Great, so the voltage you see is likely an internal pullup on X1 The Relay (and subsequently your jumper wire / ARM/RUN panel switch should thus also) close X1 to GND labelled COM on VFD (not 10v)
I added a single pole switch between COM and X1 and I got the spindle to work with M3! It also stops when M5 as long as the switch stays on, but the VFD stays in RUN on the control panel. I have to think about a better way to do this for actual CNC workflow, I wonder if I should use the old BOBs 12v relay? The shopbot that I teach on at our local maker space has a momentary switch as a last failsafe before a program runs, which is nice. Also, Peter - did you say I should expect 5v constant from the DIR pin on the Black Box after M3 is sent (until M5?). I don’t see anything coming from this pin.
That's how we deal with it. Panel mount "safety" switch to take it out of RUN mode for toolchanges, etc, switch to RUN mode rest of the time. M3's S value enables the spindle. VFDs Min Freq parameter set so it doesn't start until commanded for say 7.2kpm so you can turn it off by setting M3S <7200 Seeing as we know your VFD has 24v pullups. Guess what happened when you connected a 5V logic pin to it.... Dir pin is fried for sure As earlier, but that warning was too late
Yeah the motors and spindle work as expected. And if I’m not utilizing DIR anyway maybe I dodged a bullet. What else would I keep an eye out for if I toasted any other circuitry? At least my misstep is documented here so no one else has to repeat it.
You know how you wake up in the middle of the night thinking about these things.... While I do understand that if I had connected a jumpered X1 / COM of 24V back to the DIR pin on the Black Box, that would be bad. But I never did that - the voltages I reported above for X1/GND and X1/COM were all while the Black Box was disconnected and the old BOB was installed with the NO-Relay. When I initially tried the three wires from the Black Box to the VFD, there was no jumpering. In thinking back to the steps I took, I remember measuring the voltage from DIR before I added any jumper wires over on the VFD and found only a few millivolts (see #2 above). When I wired in the switch between the jumpered X1/COM, the DIR pin on the Black Box was unused.
Followed by Was what alerted me. X1 seems to have a 24v pullups (from the VFD not the BoB) as most VFDs do. Some has a jumper for pullup voltage
So you're saying there is an internal 24V pullup to X1 within the VFD, not on the external terminals, that was activated when it was in RUN / keyboard mode? EDIT - I just pulled all the wires from the VFD, and then plugged it in and there are 18V between GND and X1. So there you have it. Don't connect X1 on a RATT MK100 VFD to DIR on a Black Box!
Not just the RATTM, all of them! Unless the manual says its a 5v input. Always best to follow the docs: - docs:blackbox:connect-vfd [OpenBuilds Documentation] - no mention of DIR as we don't use it under normal circumstances. Our recommendation is the jumper and only GND+0-10v along with VFD parameters to suit (min freq etc properly set) - and last paragraph of docs:blackbox:jumper-relay [OpenBuilds Documentation] for the "esoteric configurations" - Uses DIR pin as an Enable for the odd VFD that doesn't turn off with only 0-10v going low (Huangyang GT series etc) but through the relay as it should be (dry contact, voltage agnostic, has its own drawbacks like enabling spindle during bootloader phase unless you flash Grbl with an ICSP bypassing bootloader)
Thanks for holding my hand through this Peter. I hope gaining this knowledge doesn't cost me another $200 for a second Black Box!
So far looks like you dodged the worse of it (; Checkout the docs if in doubt, and then of course other sometimes forgotten tips like don't spin motors by hand (they become generators), don't do any wiring with any power (even USB) turned on, check and recheck wiring before turning anything on etc
All good tips, thanks! I am staring at how I am attaching and wiring all of these things (VFD, power supply, Black Box, 4-gang box, VFD Spindle Switch) to a board on the side of my machine, and after reading the OB doc about VFD and USB interference, wondering if I might try to physically separate the VFD from the Black box by a few feet. I did also get an iOt relay for the coolant pump and dust evac, which will be wired to a separate 15A breaker circuit than everything else.
