I’m preparing to perform a bench test of the ESTOP and Holding Brake circuit but before I do that and make a mistake that fries something I want to get a sanity check from Dr D Flo or anyone who has attempted to hook this up. I didn’t see a diagram of this circuit on the project page. Thanks!
This could be just a labeling issue but I think it may be more than that. My understanding of the pins 19 and 5 on the Dyn4 is that it is a simple relay. This relay is meant to trigger your relay that supplies 24VDC to the brake. In your drawing you have + and - load leads going to the relay from pins 5 and 19. This will cause a short circuit when the Dyn4 closes the internal brake relay. There should only be 24VDC going into pin 5 and pin 19 will supply this 24VDC to the relay trigger. There is only a small amount of amperage allowed through these pins.
I would run this by DMM before trying.
Just to add a bit more, I think you have a misunderstanding of relay function, unless the drawing is mislabeled. There should only be one “common” on your relay. This would be the common required to trigger the relay. There are other issues with your drawing as well. If I have time I will draw something up that I think may be what you are trying to accomplish. Not really knowing the rest of your system will hinder this a bit but I may be able to clear up some of the brake issues.
I have had some discussions with DMM on the brake circuit recently. I am currently building a 4th axis powered by Dyn4 etc. I have also built a lathe using DMM servos. Their drawings can be difficult to follow at times. I am no electrical engineer. Far from it.
Another issue I wanted to bring up: is this a z axis brake to prevent the z axis from falling when the Dyn4 is not enabled?
Yes, this is to keep the Z axis from falling. I tried using David’s videos to determine the wiring. There were a few connections I could not be positive of by pausing the videos to trace the wires so I’m sure I have some wrong.
Here is a picture of the relay. I don’t see a common connection. Same one David used.
I’ve also sent my drawing to DMM technical support but wouldn’t expect a response until next week.
Thanks for any help!
I do not understand that relay. Not sure why they have + and - signs on both sides. This may be a relay that is beyond may knowledge but that would not take much. The SS relay I used has 4 lugs as well. I can’t find a wiring drawing for that relay. I guess it is a secret. The relays I use for these types of circuits are simpler and just require voltage to trigger a wiper and then pass the load through the wiper either NO or NC. This one seems to do more than that and I do not understand it. You may be right on this one but don’t take my word for it. David is probably more knowledgeable. When it comes to electrical, I’m more of a beat my head against the wall till I understand it enough to fry something and repeat.
The reason I asked about the z axis is that I have been told many times not to use the Dyn4 circuit to control the brake used for this purpose. The reasons given were that there are other times that the brake should be engaged other than when the DYN4 circuit closes and or the stop is activated. I never saw the logic in the reasons and never ended up needing it anyway. I used gear (belt) ratio and counterweight to solve this problem. The problem with using a brake is that it only is active when there is power to run it. If the power to the power supply is off then the brake will not engage. This is fine while the system is on but will not stop the z from creeping while it is off. It appears your power supply for the brake is fed 220 through a contactor. No matter how you wire this, if there is a power outage, the brake will disengage.
Not trying to rain on your parade and I was unable to find a video where David used a brake on his z axis. I am only aware of his 833 mill which uses gas springs to counter the z gravity issues. It’s been some time since I visited and there may be something new however. If it were me, I would try to find a non-electrical means to counter the z creep.
I ended up finding the video where David upgraded to DMM Servos. Apparently, the brake is spring loaded and engaged when no power is applied. This would work great. This is not how it was explained to me when I was looking into this.
The latest build I was doing with the DMM servo with a brake actually required a brake that did the opposite of this. No need to get into it because I scrapped that idea anyway. Sorry to confuse your build. I do think you still have some issues with your wiring diagram, however. Make sure you get some professional advice before you fire it up.
One more thing that you may or may not be aware of with the Dyn4 drives. I have found this to be very useful and creates a much more accurate and repeatable zero on an axis. The DB9 output on the DYN4 has a ZRI output. This is a pulse that is sent through 2 of the DB9 when the encoder reaches its Zero position (once per revolution of the servo). You can use this signal to precisely zero each axis. This will work and wire up differently depending on the controller you are using. I use a centroid controller. It will require between 1 and 3 (on a 3 axis mill) extra inputs on your controller. It also requires modification to your homing program.
The way it works:
When you start homing, the z axis finds your limit switch
Then the servo reverses extremely slowly until the pulse it detected on the ZRI input. Less than one revolution of the servo. The pulse is extremely quick so the feed rate of this process need to be set slow enough for the controller to recognize it.
Z axis zero is set here instead of where the mechanical zero was detected.
Repeated for all other axis
This process virtually eliminates the repeatability problems with mechanical and proximity limit switches. This is very useful in situations where you may have lost “steps” due to a crash or power loss etc. you can re-home and be 99.9% sure you are back where you started as long as the stock did not move. Be aware that the lower the gear ratio of your axis and lower the accuracy of your mechanical limits will cause this ZRI homing to be less accurate. But with highly accurate mechanical limits and ZRI homing, this is exceedingly accurate and repeatable.
I used this feature on my lathe and I basically can rely on my X axis part centerline to always be correct (for the reference tool) even between power cycles. Very handy on a lathe.
Another long-winded reply has come to an end. Good luck with your build. I am happy to help if you so desire. I have converted several machines using different technologies. The DMM route is more complicated but also very high quality.
This is my version of what you are looking for.
My assumptions in this diagram are:
that the Dyn4 pin 5 and 19 are NO.
When the drive is enabled, there is no fault and has power, the pins 5 and 19 are closed by the drive thereby powering the brake to disengage. And vise versa
I also assumed that the input of your relay is the trigger and the load terminals are the closed by the wiper that is controlled by the trigger voltage. I have yet to find a wiring diagram for that relay and I do not understand the nomenclature on the relay itself.
Update. I very intensely watched David’s video again and was able to determine my wiring diagram matches his, so I hooked up my original diagram and it worked. The change I made was to connect the common pin from the DYN4 directly to the (-) 24V DC Power Supply. Prior to that I had it connected to the Mesa board. The contactors would close but the relay would not release the brake until I changed that connection. That allowed BKO (pin 19) to send the signal to the relay to release the brake. If you watch David’s video, I get the same results using the same components. The contactors close then about 2 seconds later I get the green light on the relay and can hear the brake release. The only difference in components is I have a 7i96S Mesa Board.