I'm going through the BlackBox documentation and playing with the various features and I'm a bit confused about the internal relay. I see we have the jumper for M3/M5 and M8/M9, and the way I read the documentation is that the internal relay should have three operating modes. 1: Jumper in M3/M5 position: Expected behavior: relay should open and close based on the M3/M5 commands. 2: Jumper in M8/M9 position: Expected behavior: relay should open and close based on the M8/M9 commands. 3: Jumper open: Expected behavior: The relay should be inactive. What I'm confused about is that when in the M3/M5 position, the relay doesn't seem to open and close.
Make sure to send M3S1000 (if you havent changed grbl default $30=1000 that is else substitute S1000 for whatever it is set to) M3 set spindle to clockwise and enabled. S1000 sets the pwm to full on Grbl needs both words to do what you want it to do
Perfect I can now see everything turn on with M3S24000, but oddly if I try to change the speed to below 10-13k RPM it just shuts off. I have the Grbl min set to 7200 RPM, and the corresponding min frequencies in the VFD set to 120hz which should correspond to 7200 RPM. I'll keep digging into this. I'm guessing it's some parameter in the VFD I need to look at. Thanks again for all of your help Peter.
Is the signal that is ,sent over the relay er, driving the relay rather, the same signal that is sent to the 0-10V pins? If so I'm guessing we are going below the relay turn off voltage and that's why I'm getting shut down at around half of the speed range.
Assuming what I'm thinking about is true, lead me to think about the following. What I'm wondering is if I could split off the 0-10V signal and add a voltage regulator (5V or 12V) to drive an external relay. I'm guessing the relay I would use would draw somewhere around 100-150mA would that much of a current draw cause any issues for the 0-10V signal generated on the BB. I've done more reading on different forums about just jumpering DCM to FOR on these VFDs and I guess it can present a safety issue. Even if you can get the spindle to shut down when the 0-10V signal is 0V I guess there is a non zero chance the spindle could start up anyhow. So without a relay it's not guaranteed that stopped will stay stopped. So I've been thinking about the issue of driving a relay from the 0-10V signal, but it's hard to find a relay that has a sufficiently low drop out voltage to be able to get the full speed range. But thinking about the issue and looking at the voltage curve for the 0-10V control circuit I think I could get the full range that my spindle can operate at. 7200RPM represents about 30% of the range and from the charts I could find would put the voltage somewhere around 2V which is a high enough voltage to operate many 5V regulators.
Hi @Paul Stoller, I don't understand your last post. A voltage regulator takes an input voltage above it's rated output and limits it. So a 5V regulator needs an input above 5V to give a constant output of 5V. If the input is less than 5V you would get out what you put in. I think (correct me if I have misunderstood) you are hoping to use the analog 0-10 V output from the blackbox to switch the coil of the relay while the relay contacts (when the relay is on) carry the same signal to your VFD. Your only hope of doing something like that would be to use a transistor circuit to switch off the connection between the blackbox output and the VFD (bipolar silicon transistor would turn off if base/emitter voltage drops below 0.7V). Alex.
Ah I was misreading the spec sheet for the regulator I was looking at, seeing the minimum voltage and thinking it would also boost the voltage. I’ve got some transistors on hand as well, I’ll need to double check the type I have to see if they would be appropriate. Thanks for the suggestion.
Hi @Paul Stoller, you could use a simple transistor switch circuit to turn on a relay when the 0-10 V output rises above 0.7 V. You must wire a reverse biased diode in parallel with the relay coil to protect the transistor from the back emf when the relay switches off. You would need a positive power supply that shares the same ground as the 0-10V output for the relay coil. I don't know enough about the blackbox circuitry to advise further on this. Alex.
It's a good start on what I'd need, thank you again for the direction. Once I get some time later today I'm going to work up a circuit to breadboard.
I just checked the parts I had on hand and I've got some 1N4004 diodes and 2N2222 transistors. Glancing over the spec sheets I think these parts could be made to work for this application.
A 5K/10K resistor between 0-10V and transistor base - transistor not critical as it will dissipate very little as it will be fully on or fully off. Yes - npn transistor - relay coil between +V and collector - don't forget that diode! Can you not use the on-board relay or are you thinking of using that for something else? Alex.
I was going to get into eagle and draw up a schematic for this circuit, but I think I found a good example of the circuit your describing. Replace the Arduino Digital Pin reference with the 0-10V signal, and then share the grounds as you suggested.
I've tested using the onboard relay, but it is cutting out at about half of the spindles RPM range. I suspect the internal relay is being driven by the 0-10V signal and that when I adjust the RPMs down below a certain point it going below the relay's drop out voltage, it's just a suspicion at this point, but that would match the behavior I'm seeing when testing it.
Not knowing what the 0-10 V output can source in terms of current I would be inclined to increase the base resistor from 1K to 5K. Otherwise that looks right. Alex.
Grbl only has one spindle output. The relay is already driven by a Transistor Alex. The problem is the pin outputs PWM. Of course the relay will chatter at lower RPM values, so its more of a 'use the relay (actually there as a plasma trigger)' or use PWM, but both wont play nice
Two part question, would increasing the PWM frequency help alleviate the chatter issue, and is the PWM frequency changable?
It is changeable, not sure if it would help. Its just not what it was designed for. We added the relay as a) plasma trigger (no pwm at play) ir b) spindle or pump switch (just on off, not pwm, relays are meant for on off work) I didnt realize you want to use it as enable, that would not work. Wire up DIR like we discussed in the other thread man that will do
My goal is to be able to run the spindle at full RPM range and have the M3/M5 commands successfully turn the spindle on and off. For that I would need to change the definition of the DIR pin in grbl to be an enable pin rather than direction?
The "correct way" is still to figure out that minimum voltage VFD setting so the PWM is all thats needed, with DIR setting FOR/REV It can be done, we just need to crack the right settings on your VFD. See if you can find a PDF of its manual for me to look through please
Didn't fully understand what Paul was trying to do - I agree - don't drive a relay with pwm - it won't last long! Alex.
Thanks for the help, but theres a lot of history in that one I'll take it from here so it doesnt add more confusion
No problem I'm willing to go down that path, I just got concerned when I had read some folks saying a relay was required for safety. That being said I don't plan on changing tools with the machine on at all to begin with if I can avoid it. Here is a copy of the VFD manual. http://www.hy-electrical.com/bf/inverter.pdf
Thanks to both of you, in hindsight I might have been better to keep everything in a single thread. My thought was as I was trying different approaches, or trying to understand specific behaviors that I would have a more focus thread, but since it's all interrelated that wasn't the best thought.
I wouldnt trust the relay thats still under software control any more than the PWM signal. To me those are the same level of safety. I see the point though but a switch inline with the PWM signal may be even better flip it when you want to "DISARM NUKE" hehe
Thanks Peter, I've tried the full range of values for PD010 which seemed like a promising setting, what I'm wondering now after having tried the full range is if there isn't another related value that also need to be within a correct/proper range.
Found online: PD001 = 1 ; required to use PWM signal as the activation trigger (default was 0=manual) PD002 = 1 ; required to use PWM signal as the RPM input (default was 0=manual)
Looked over the manual, and PD010 is output voltage to control the torque curve? @Critical is PD010 something dfferent on yours? (Like I said in your thread earlier - seems some VFDs do, some dont!) (XPro v4 won't control VFD & Spindle relates)
