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12v12 motor drivers carrier board


#1

I made a carrier board (expressPCB service) for two 12v12 motor driver boards in one enclosure. All was well until I tried to plug in the usb without having the motor power supply on, guess I should have known better. The unpowered boards /rst lines holds the other boards low so i had to put on some diodes. All is well now though. I used rs232 in/out for cmds and feedback info and they are cascadable (I am using 8 boxes and 8 linear motors). The pattern for the plug ins for the boards was a challange to measure they don’t seem to be on any standard spacing to each other. I am pretty happy with the boards but wish they had decelerate control as well as accelerate.



#2

Hi.

Thanks for sharing your project with us. It looks cool, and I am glad you were able to solve your problem.

As for your request for deceleration control, I suggest changing the “When motor is off” parameter to “Coast” and try using the “Brake duration” parameter. However, if that suggestion is not adequate for what you are trying to do, then we do have a custom version of the jrk 12v12 firmware that includes deceleration limiting. Please note that this custom firmware was based on version 1.3, so it does not include the bug fixes that were made in version 1.4.

- Zeeshan


#3

That is interresting to hear that is is a possible upgrade. I have the brake select on because my control program in the PLC does not send a stop command before sending new position commands and it could be reversing direction because of that. I blew up one of the smaller 3a jrk drivers when that happened so changed to the larger boards. The brake selection on the jrk board seems to do the stop then reverse automatically. I could reprogram the PLC to do that but have been in a bit of a rush to get it functioning. It is very cool to watch the 4 pairs of linear motors drive in sync. This week I will doing life and load testing on the motors and controllers at 60+ lbs each and hopefully better than 25% duty cycle. I also added heat sinks to the driver chips to help cool them. The AND gates work very well to read back the position and current data from each of the motors drivers to the PLC. It seems like a lot of stuff for farily simple functions but I needed to make it reliable and maintainable.


#4



#5

[attachment=0]DSCN0520.JPG[/attachment]


#6

Thanks for posting photos of your project. Wow, that looks great!

I am really interested in what your project is for; could you tell me more about it?

- Zeeshan


#7

I was reading the thread on the decelerate firmware change. I can’t tell for sure but do you also lose position readings and current readings? Unfortunatly I am using both of those in my code

I did change the driver boards to coast as was suggested but it runs by the set point by quite a bit and then backs up.
How would I get the origional firmware back in the devices if it doesn’t do what I need?


#8

hi Zeeshan,
Thanks for the information and it helps me alot. che:-)


#9

You should still be able to read position and current with the custom firmware.

You might try adjusting your PID parameters. In general, the standard way to prevent overshoot is to adjust your PID parameters. Did you only change the “When motor is off” parameter to “Coast” when this behavior started? If you want help debugging, can you post more information about your setup (i.e. settings file)?

In order to restore your jrk’s firmware, you can follow our directions to upgrade the jrk’s firmware under the “Upgrading Firmware” section of the jrk user’s guide.

- Zeeshan


#10

I had purchased two extra boards to play with and did put in the firmware change to the one of them. It refused to work after that, so I may have done something wrong (It did work before) . The board did say v1.3 but no motor running at all. The yellow light is on and it recognizes the usb but that’s it. I then put 1.4 back in and still nothing.
So I tried the second board and it did take the change. The default PID really did act differently because the motor would not stabilize. I am pretty sure the pid settings could have been adjusted to help stop the oscillations.
As much as I would love to have the decelerate I am concerned with taking out any more boards and really would be great if the firmware didn’t loose the current and speed limiting.

If there was a compromise firmware that just made acc/decel to be the same value that would make a lot of difference and I wouldn’t think it would be that much of a change to have to remove the current limiting. So if you have a wish list put it on there.
I really do like these little controllers but for that one missing piece.

I will play with the PID with the rest of the boards I have using v1.4 to see if I can take out the overshoot that way.