Limit Switches and Homing Issue (Solved)

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Chris
Posts: 9
Joined: Sat Dec 08, 2018 8:03 am

Limit Switches and Homing Issue (Solved)

Post by Chris » Sat Dec 08, 2018 9:53 am

Quick question – I’m having problems homing my Buildbotics. I’ve install limit switches correctly and can see the status change in the indicators tab then the switches are activated. The problem I’m having is when I go to home the x and y axis as soon as the limit switch is triggered the Buildbotics detects this as an estop and does not follow the expected backoff, latch actions. I’ve only connect the motor limits switches to pins 3,4,5 and 8 (for M0 and M1 min & max switches) with power/ground going to pins 6 and 7 on the DB25 I/0, I’ve using Makerbot limit switches.
9CED5175-89F5-4CF9-BA05-CCA290C89765.jpeg

Can you please help me figure out what’s going wrong?

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Doug
Posts: 343
Joined: Fri Feb 02, 2018 4:56 pm

Re: Limit Switches and Homing Issue

Post by Doug » Sat Dec 08, 2018 12:28 pm

Chris,

You have to set up the soft limits on your motors to make the limit switches work correctly. Try setting those up on the Motor configuration pages and let me know how it goes.

Chris
Posts: 9
Joined: Sat Dec 08, 2018 8:03 am

Re: Limit Switches and Homing Issue

Post by Chris » Sat Dec 08, 2018 1:06 pm

Thanks Doug - I've set both the X and y soft limits setting as followings but still getting the same issue that when the switch is triggered the Buildbotic controller triggers an estop rather than the homing sequence.
softlimit.png
Many thanks
Chris

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Doug
Posts: 343
Joined: Fri Feb 02, 2018 4:56 pm

Re: Limit Switches and Homing Issue

Post by Doug » Sat Dec 08, 2018 1:49 pm

Chris,

From your first post, it looks like the Motor 0 min switch is active. It is possible that the switch is still engaged. If you can see it, please verify that it has opened. Another way to test is to verify that you do not have ground on pin 3. If the switch is still active, try increasing the latch back off distance on the motor configuration page.

Doug

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Doug
Posts: 343
Joined: Fri Feb 02, 2018 4:56 pm

Re: Limit Switches and Homing Issue

Post by Doug » Sat Dec 08, 2018 2:02 pm

Chris,

The problem may be that the limit switch is engaged before you even start the sequence. Try disabling the min 0 switch in the Motor 0 configuration page. Then clear the estop by clicking the estop button. Then move the spindle away from the switch. Then, re-enable the switch and try your homing sequence again.

Just so you know, we have some beta software that has some nice new features, one of which improves the homing and probing processes. If you are willing to accept the possibility of some unexpected actions (due to beta software), I can send it to you. We hope to release this new software shortly so it's getting pretty close to being ready for production.

You can update software from a local file using the "Upload" button.

Doug

Chris
Posts: 9
Joined: Sat Dec 08, 2018 8:03 am

Re: Limit Switches and Homing Issue

Post by Chris » Sat Dec 08, 2018 2:32 pm

Thanks Doug

More than happy to beta test the new release - I’ll have play with the current settings this weekend.

Many thanks
Chris

Chris
Posts: 9
Joined: Sat Dec 08, 2018 8:03 am

Re: Limit Switches and Homing Issue

Post by Chris » Sat Dec 08, 2018 3:42 pm

Thanks Doug - new firmware has fixed my webcam issue (Logitech C920 HD Pro), but still having the same problem with the homing.

Will have a play in the morning (23:40 here in the UK). Below is the wiring diagram for the endstop I'm using in case you can see anything obivously wrong there.
DB25_breakout_box_makerbot endstop.png
Great support and awesome product - please keep this up!

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Doug
Posts: 343
Joined: Fri Feb 02, 2018 4:56 pm

Re: Limit Switches and Homing Issue

Post by Doug » Sat Dec 08, 2018 4:47 pm

Hmmm,

Please reply with your system configuration as an attachment. You can get your configuration using the following procedure:
1. Go to the "General" page on the Buildbotics Controller.
2. Click "Backup"
3. Save the resulting json file to your local computer.
4. Attach that configuration file to your reply to this post.

That json file will have your machine configuration on it. I will set up my machine using your configuration and try to simulate the problem. Hopefully, that will lead me to a solution.

Chris
Posts: 9
Joined: Sat Dec 08, 2018 8:03 am

Re: Limit Switches and Homing Issue

Post by Chris » Sun Dec 09, 2018 1:34 am

Thanks Doug

Config file attached. I'm building an OX CNC 1000x1000mm.
bbctrl-20181209.zip
(948 Bytes) Downloaded 382 times
Many thanks
Chris

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Doug
Posts: 343
Joined: Fri Feb 02, 2018 4:56 pm

Re: Limit Switches and Homing Issue

Post by Doug » Sun Dec 09, 2018 8:03 am

Chris,

Thanks for sending your configuration. I have it loaded on my machine. I had to make a few changes in the limit switch configuration to make it match my machine. I only have limit switches on one end of each axis.

I ended up with my x-axis limit switch being wired as a maximum limit but your configuration had it assigned as a minimum switch. When I attempted to home, it resulted in the exact failure that you have described. In other words, the machine goes into e-stop as soon as the switch is closed. More succinctly, while the machine was searching for xmin, xmax activates causing estop.

I suspect confusion may have occurred because, in the past we assumed that people would connect motor 0 to the X axis and motor 1 to the Y axis. So, we used to call pin 3 x-min, pin 4 x-max, pin 5 y-min, and pin 8 y-max. Of coarse, this was silly because users are free to assign their axis to any of the motor outputs. I noticed that you assigned your X axis to motor 1 and Y to motors 0 and 3. In the new version, you will notice that we named those pins motor 0 min, motor 0 max, motor 1 min, motor 1 max...)

So, I have to ask you to double-check your limit switch wiring. make sure they are wired as follows:
* Motor 0 min goes to pin 3 (your y axis minimum switch)
* Motor 0 max goes to pin 4 (your y axis maximum switch)
* Motor 1 min goes to pin 5 (your x axis minimum switch)
* Motor 1 min goes to pin 8 (your x axis maximum switch)

I apologize for the confusion and hope this gets it fixed. Please let me know how it goes.

Doug

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