Sticking Home/Limit Switches - Please help

andypugh wrote:

Clive s wrote: I don't think I would connect the 0V from the 48V power supply if that is the one to power the steppers.

Indeed, it is likely to introduce noise from the chopper in the drive. Though some drives make the connection for you, unfortunately.

This is all a but puzzling.

What voltages do you see across the inputs with a multimeter?

Using a multimeter across the pins on the BOB I see 9V.
I have tested with standard switches and also switches that have resistors limiting it to 5V.

Just an update...
I have been working on the machine all day (still doing config stuff)with all switches in NO mode, and it was working fine for homing.
BUT, it seems that after a few hours - even with all switches being NO - something sticks.
e.g. Z homes, makes contact with the switch (verified via halscope) then it backs off, the switch is physically disconnected but halscope shows it as connected for another 5-10 seconds.

So it seems that the issue is continuing to grow in intensity.

It seems to me that there may be a build up of something (im not an electrician but perhaps static, emi, atomic radiation???)
That's the only explanation I have about why it just keeps getting worse and worse..

Apart from ordering another Motherboard and Stepper Drivers, does anyone have any ideas?

Another update...

For Z (untested on others)

If I Jog - then manually activate home switch, it sticks.
Jog z + , switch toggles perfectly fine

WTF?

I am seriously at the point of just buying one of the ready made BOB and Controllers...

Following this from the start, i can only come to a conclusion that something is very wrong with the :
Power supplies making to much ripple
BOB with personality issues <<<<least likely
Miss wiring on the ground side of the things, therefore creating a different potential between pins.

You mentioned that you get 9V at the BOB pins, that is not OK in any way for a 5V BOB, see above about ground <>potential.

You mentioned that you get 9V at the BOB pins, that is not OK in any way for a 5V BOB, see above about ground <>potential.

I have not checked but going from memory this bob inputs are fed from the 12-24V power supply and I think they could be at 9V. This is why I asked for a drawing of how it is exactly wired up preferably with a pic.

Clive you're right, it is fed 12v for the inputs, and I have seen mention elsewhere of 9v across the pins.

I just spent an hour trying to make a diagram but the tool got too annoying so I trashed it...

Might try paper and pen...

Here it is, Obviously just repeat stepper motors and switches...

I hope this can clear some things up

Each switch is wired to an input pin and the shared GND terminal?
What voltage do you measure between the terminals and the shared GND 1) When no switches are triggered 2) When they have "stuck"

andypugh wrote: Each switch is wired to an input pin and the shared GND terminal?

Correct

andypugh wrote: What voltage do you measure between the terminals and the shared GND 1) When no switches are triggered 2) When they have "stuck"

1) 9v
2) 9v
3) 0v (when triggered - currently in NO)

I can also confirm that they only get stuck when jogging/moving in + direction, not when moving in -

When they have stuck I can still see the voltage go from 9v to 0v when triggered.

Maybe I can try to measure the voltage on the DB25 Connector pins... But not sure which ones

So, the voltages at the screw terminals behave correctly, but the values on the parallel port pins don't.
How curious.

You could try measuring the voltages on each side of the opto-couplers (input and output pairs)

I am away for a few days. But I take it you are using a correct type of PP cable as they are not always pin to pin. Try another one.