PWN Spindle and estop

I hooked up a 2.2kw spindle kit and tested it with my new elite machine. Controls so far look to be working correctly, I can start and stop the spindle with the machine codes from the MDI. If the Onefinity Estop button is pressed, then the spindle won’t start even when i tell it to. However sometimes when the spindle is running and I test pressing the estop, it does not always stop the spindle. Has anyone else noticed this issue? If so have you been able to identify the problem and come up with any solutions?

Hey Adam. Can your provide more details? For instance, what spindle/VFD did you install? I have had both the Huanyang VFD/Spindle (from Amazon) as well as the PwnCNC spindle kit (with VFD). The PwnCNC spindle kit is amazing and works perfectly right out of the box with the Elite Masso controller…at least it did for me.

The Huanyang I had some issues getting programmed correctly and then I had to go through 3 different DB25 connectors to connect the VFD to the controller (Buildbotics) because of the issues with it (much like you’re experiencing with intermittent working/not working).

Sorry this response seems to be all over the place; but, without more information about your setup…it is hard to pin down a suggestion.


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What version of Masso are you running?

v5.06 software is what the Masso is running. I have not done any updates but i just got the machine so i would assume that’s the latest.

I did contact PWN and put in a ticket. They replied quickly and made it sound like it was a known issue with Masso and that they (PWN) have no control over it. I am wondering have other users also noticed this? To me its a big deal, the spindle is very powerful and i would not want there to ever be a problem and not have a quick way to shut it off.

What exactly did they say the issue was that the Masso controller was responsible for?

Does PWN provide any wiring details or schematics as to how they set up and interface their safety circuit?

I am sure if this information was made readily available, and passed on to Masso through their forum, it would be addressed.

Adam, this is a quirk of the Masso controller. We have tried several different ways to rectify this issue and as far as we can tell it’s not possible to get the spindle to stop with the estop button.

Was the first reply…
Here is the second.

Adam, this is nothing we have control over. The Masso “controller” controls the spindle. What happens when you hit the eStop and whether or not the voltage being sent to the VFD to tell the spindle to turn and at what rpms is a Masso issue. Of course we’d like it to stop. However all we can do is request improvements in future firmware updates but up to this point we’ve not seen any changes implemented

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Am i the only one that is noticing this issue? Do other people with the same setup have the same problem?

I have noticed its not perfectly consistent. Sometimes the estop stops the spindle on the first press. Sometimes it takes an estop press, spindle keeps running, reset the estop, and press again to stop the spindle. So far i have not seen the spindle run past 2 estop presses.

Has anyone else seen this or is it just mine? PWN sounds like they are aware of the issue.

That answer is a bit misleading in my opinion.

The Masso controller controls the spindle, this is true, and how it does so has to do not only with the controller but also how the VFD has been configured.

It is the same with the Estop and safety circuit. Masso has an ES output tied directly to the Estop input. This should be used to safely stop other equipment, usually with the additional functionality of a relay, and how this is implemented depends on the level of safety you wish to achieve.

Most VFDs have trip input functions that can be configured, and this would not require the direct involvement of the Masso controller, rather it would be triggered simultaneously when a double acting Estop button is pressed. For those that want a different level of safety, these can be configured to cut power.

It is for these reasons that I am interested in the wiring diagrams and circuits used by PWNcnc, and also why I question any issue with Masso’s functioning.

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I agree, maybe we need extra wiring from the estop or the masso to the vfd. Maybe we also need to change parameters on the vfd.

But the bottom line is the stop function should be reliable. Thats why i am wondering do I need to come up with a solve for this problem or is there something just not exactly right about the setup i received. If others have the same issue and just live with it then i will need to modify to fix it. If i am the only one seeing this issue then maybe a setting or something is all that is wrong.

I think it is worth finding out how it is currently set up to work by PWNcnc, especially if purchased as plug n play for the Elite machines. It is also worth investigating as you may want it to work differently depending on what you consider safe.

I went on their website and downloaded the VFD manual. As with most it is voluminous, but I did see options for setting up internal relays, as well as fault inputs/outputs. I did not do a deep dive yet, but perhaps others with more experience with the Delixi series VFDs can help.

It would not be too difficult to tie into the Masso Touch Estop circuit and use it to control a VFD fault input.

Hey all,

the Emergency Stop on Onefinity Elite’s custom variant of the Masso G3 Touch is not wired the way that Masso describes vs. recommends, but it is a Onefinity custom wiring that puts all stepper motor “Enable” wires in a circuit together. So when you press Estop, the stepper motors are disabled and stop moving.

The only allowed way to stop a spindle, including emergency stop, is to use the STOP mode of the VFD (either through VFD front keypad, Modbus command, or programmable input terminal with STOP function assigned to it). This is done either via a Modbus command, or, if the CNC controller does not support Modbus communication, by activating a programmable input terminal of the VFD that is assigned to the STOP command (some VFD also have dedicated Alarm function that can be assigned to input terminals, e.g. like described here). So the strict requirement of stopping the spindle when estop is hit (be the estop button located on the CNC controller or on the VFD control cabinet’s door) has to be implemented in a way that the estop signal triggers the STOP function of the VFD. According to the updated IEC 60204-1, a VFD’s spindle STOP command is considered as a valid Safe Torque Off (STO) that fulfils the stop category 0 requirement (so allows to e.g. safely manually change the tool in this state).

If you want to comply to IEC 60204-1, you would even need to do more:

But besides this very strict requirement, I think that simply implementing the requirement that on pressing estop, not only the steppers are halted, but also every actuator, i.e. the spindle is ensured to be stopped, which can only be implemented by sending the VFD the STOP command, needs to be done by attaching something to Masso G3’s ES output which triggers (ususally via a relay) a programmable input terminal on the VFD that has been assigned to the STOP function (or, if supported by the VFD, to the dedicated emergency Stop function according to IEC61508 & ISO13849 (see Appendix E in Omron MX2 manual).

So I think this Masso diagram shows how the VFD has to be stopped correctly:

– Source: EStop Wiring – Masso Documentation

As explained above, in this diagram, the “Emergency” input of the VFD means one of the programmable input terminals, assigned either – if present – to the dedicated emergency stop function, or to the regular STOP function that is sometimes implemented by disabling FWD RUN (and REV to be strict). On the Masso spindle/VFD control wiring examples, this pin is already assigned this way for regular RUN/STOP, and can be used for this purpose if you make sure that STOP cannot be reversed while Estop is active. As already mentioned above, according to the updated IEC 60204-1, a VFD’s spindle STOP command is considered as a valid Safe Torque Off (STO) that fulfils the stop category 0 requirement.

Thanks all for the suggestions that is completely in line with what i am thinking needs to be changed.

I will rewire/ configure such that the estop disables the drive. That way even if the masso was telling it to run, the safety would not allow it. Instead of just relying on the controller to shut off the run command in the event of an estop.

But at the same time I am very curious, am I the only one who has the Elite machine/ PWN spindle kit that is noticing this problem?

Does anyone have the same setup and yours works properly as far as the estop goes?

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Hey Tom, hey Adam @ARiddle, hey all,

I don’t have experience with Daniel’s @PwnCNC VFD (and the way he does the control wiring) either. He offers different wirings and programmings depending on whether you have a Onefinity Elite Masso or a Buildbotics/Onefinity or something else, but I never had one of his VFD enclosures in my hands. I think Daniel knows everything about this VFD’s possibilities and capability.

This sounds like if the Masso G3 should stop the spindle by firmware by using the existing FWD/STOP wire on the GX-12 Elite spindle control cable. With the Masso wiring diagram I showed above, another solution is shown which sends the STOP signal to the VFD from the Masso’s ES output.

The only solution to control a VFD with the Masso G3 (on the buildbotics the thing is more easy as the controller simply sends the spindle stop via Modbus command) is to trigger one of the VFD’s input terminals that was assigned to either STOP (or disable RUN or FWD and REV which is the same), or if present, a dedicated emergency stop function. Neither Onefinity’s variant of the ES output wiring, nor its proprietary ESTOP/Stepper “Enable” input wiring, does take care of stopping a spindle. But should the Masso G3 stop the spindle by its firmware, the same way it stops the spindle when it encounters a M5 (stop spindle) command in a g-code program? If so, this would be sufficient, but it would be a matter of firmware only.

As far as I understood, because of the Modbus interface missing on Masso G3, the Masso controls the VFD/spindle only via the analog 0–10 V input wire for spindle SPEED, and a wire to the FWD input terminal for spindle RUN/STOP function. So what the Masso G3 could(?) or should(?) do, is trigger by its firmware this RUN/STOP input terminal of the VFD if Estop is pressed. I don’t know if it is supposed to do this. If so, this is a Masso firmware issue.

But this would mean that a Masso firmware that does not stop the spindle on pressing Estop has a an extremely dangerous bug!

So I would not rely on the Masso firmware (that’s why I would not and will never use a Masso controller anyway – proprietary, closed source firmware) and implement stopping the spindle in the way that I showed in the Masso ES ouput relay diagram above. You are on the safe side then. And whether the VFD offers only triggering STOP (= interrupting FWD RUN), or additionally has a dedicated Emergency stop function that can be assigned to an input terminal of the DELIXI VFD, surely Daniel can tell (or you study the VFD manual link above). This could require using one of the unused wires on the Elite GX-12 spindle/VFD control cable).

PS: And if you remember this, you know why no Masso will ever come through my door :wink:

Hey Adam @ARiddle, hey all,

I just had a look at the DELIXI VFD manual.

There, besides FWD (1) and REV (2) running functions that each can be assigned to one of the (only six) input terminals, I find:

Setting valueFunctionDescription
8Free StopWhen the terminal state is valid, the frequency inverter is blocked to output, the shut-down of the motor is not subject to the control of the frequency inverter at this moment. This mode has same meaning of free stop described in P1.0.16.
43Emergency StopWhen this terminal is valid, the frequency inverter outputs the voltage in enclosed mode and freely stops by inertia.

That’s the problem with manuals translated from chinese – what could this mean: “the frequency inverter outputs the voltage in enclosed mode”???

“Free Stop” is assigned to input terminal DI6 by default. I remember Daniel complained that this VFD only has six input terminals.

I think both functions, 8 and 43, will lead to the spinde to be cut from output voltage and left coasting. Safe Torque Off (STO) means always motor left coasting.

Fortunately this has been quickly corrected.

Hey Adam,

This links to the 800 Hz spindle, which is a spindle with four magnetic poles that needs double the frequency for a specific rpm than the usual spindles with two magnetic poles.

May I ask, what max. frequency is the PwnCNC VFD capable of?

I am lucky to have one that will do 580 Hz which can deliver 35,400 RPM on spindles with two magnetic poles (useful for spindles like this one and this one)

Here you see the nameplates of Hitachi WJ200-022SF, which MikeH presented here, that also more forum members run (here, here) and which is identical to the Omron MX2 that I own – with the exception of the max. frequency:

Here you see Michael’s @MikeH nameplate (Hitachi WJ200 2.2 kW): 400 Hz max. frequency

Here you see my VFD’s nameplate (Omron MX2 2.2 kW): 580 Hz max. frequency

Here you can also see that the Omron offers 580 Hz while the Hitachi only 400 Hz, but this only matters if you want to run spindles with more than 24,000 rpm (e.g. these ones). With 400 Hz, you can only run the usual max. 24,000 rpm spindles (with two magnetic poles).

If you attach a spindle that has four magnetic poles to a VFD that can do 400 Hz, it will run with max. 12,000 rpm. To run such a 4-pole spindle with 24,000 Hz, you need a VFD that can deliver 800 Hz.

Due to regulations in the US and EU (and possibly other regions), the maximum frequency capacity of commercially available VFDs is limited to 600 Hz, as experts have concluded that VFDs capable of more than 600 Hz can be used to operate uranium enrichment centrifuges and could be purchased by Iran. That is why you usually don’t find VFDs with more than max. 600 Hz capability.

There are two digital inputs wired into the Elite via the GX12 6-pin PwnCNC Control Cable. One triggers CW the other triggers CCW. Since CCW has very limited functionality for woodworking spindles, you can reassign the CCW function to E-Stop if you wish… in the EM61 VFD it’s P2.0.01(DI2)=43 is the e-stop digital function.
Then it’s a matter of rewiring the Elite’s inlet cable. Unfortunately they did not follow our color coding standard and I believe their blue wire is the DI2… This is about as far as I can take you on this journey. I haven’t attempted to wire the DI2 to an output and assign it to e-stop using the Masso controller.

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