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Author Topic: Can’t get Probe to Work  (Read 9327 times)

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Offline kolias

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Re: Can’t get Probe to Work
« Reply #10 on: March 01, 2016, 10:20:03 AM »
Here it is
Nicolas

Offline kolias

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Re: Can’t get Probe to Work
« Reply #11 on: March 01, 2016, 01:05:24 PM »
Decided to change the jumper on pins 2-9 from pull-up to pull-down but noticed no difference. Motors and Estop are working and when I touch the clip to the machine the Estop lights up on the diagnostic screen. I attach a snip of my diagnostic screen which shows no lights for the motors and I think I should have the motor lights ON
Nicolas

Offline stirling

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Re: Can’t get Probe to Work
« Reply #12 on: March 01, 2016, 01:13:06 PM »
According to your xml you only have the ONE parallel port. If that's the case you can't use pin 8 for an input.

You're already using inputs 10,12 and 13 so you'd need to change the probe input to either 11 or 15.

However there's a problem:

Ideally you want to set the input active low (and use a pull UP). But according to your BOB datasheet, page 7, that stupid BOB has all the dedicated inputs (10,11,12,13 and 15) hard wired to pull DOWNS. This means the ONLY option you have to activate these is active HIGH.

This is REALLY STUPID and makes tool setting impossible UNLESS you can somehow isolate the tool from ground.

That's why they have that REALLY STUPID diagram on page 11. i.e. THAT can only work if the tool is isolated which is practically NEVER going to be the case.

I'll have to think... time for drink here in the UK...

EDIT: just noticed you just posted again. Pins 2-9 are OUTPUTS - pullups/downs are meaningless on OUTPUTS. Please don't play without knowing what you're doing - you're going to blow something if you're not careful.

Offline kolias

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Re: Can’t get Probe to Work
« Reply #13 on: March 01, 2016, 01:55:33 PM »
Thanks stirling, enjoy your tea / Jin

It is strange because I used the same BOB and drivers / motors before and I had the probe working well with the same script / wiring as when I started this thread (black to clip and 5V with a resistor in between, red to pin 15). I don’t know what happened now.

I took a chance to change the jumper because that’s where it was before when my motors did not work.
Nicolas

Offline kolias

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Re: Can’t get Probe to Work
« Reply #14 on: March 01, 2016, 03:48:08 PM »
I found the attached probe wiring stirling on the web. Is it good for my BOB and if yes where do I get the ground to connect the alligator clip?

Can I take it to the earth ground?
Nicolas

Offline stirling

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Re: Can’t get Probe to Work
« Reply #15 on: March 02, 2016, 03:56:08 AM »
Thanks stirling, enjoy your tea / Jin

It is strange because I used the same BOB and drivers / motors before and I had the probe working well with the same script / wiring as when I started this thread (black to clip and 5V with a resistor in between, red to pin 15).

You'll just have to trust me on this. That is NOT the way to wire a tool for tool setting probe. If you say it worked then OK but it was by some strange quirk of luck that somehow your tool was isolated from ground. That is the ONLY way that could have "worked".

You don't have to trust me on the script though because after we get your touch off working I'll explain exactly why that script is a crock o' horse sh**.



Anyway - the diagram you just posted demonstrates nicely how to do things properly but as I've tried to explain - you have a problem trying to do that with YOUR BOB because the muppets that designed it, HARDWIRED pullDOWN resistors on the dedicated inputs.

See the 10K pullUP resistor on this diagram?
See the that the tool is clipped to GROUND?
See the pullDOWN on YOUR schematic?
See the tool connected to 5V on yours (albeit through a stupid series resistor who's only purpose is to stop a short if the tool actually IS connected to ground).

exactly as I've been trying to explain to you.
Compare it to your BOB manual (page 11) and hopefully you'll see the difference.

All we can try to do on your BOB is try to "over-power" your pullDOWN with a strong pullUP.

So please follow the above diagram EXACTLY except use your 120 ohm resistor instead of the 10K one in the diagram.
Then go to ports n pins and change your probe pin from 8 to 15. Leave it active low (green tick).

Then touch your plate to the tool and you should be good.


 
Can’t get Probe to Work
« Reply #16 on: March 02, 2016, 03:57:30 AM »
You may not need it.  I assume that your machine is grounded so the tool will be grounded through the spindle.  But it's good practice to have a ground wire as shown which should go back to the star point ground in your electronics.  The "copper board" of course should be printed circuit board, so the copper layer which is uppermost is normally insulated from ground until the grounded tool touches.  I find that probing works fine through the machine ground.


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Offline stirling

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Re: Can’t get Probe to Work
« Reply #17 on: March 02, 2016, 04:09:32 AM »
You may not need it.  I assume that your machine is grounded so the tool will be grounded through the spindle.  But it's good practice to have a ground wire as shown which should go back to the star point ground in your electronics.  The "copper board" of course should be printed circuit board, so the copper layer which is uppermost is normally insulated from ground until the grounded tool touches.  I find that probing works fine through the machine ground.

Not quite sure what you're referring to by "it" when you say "You may not need it".

Offline kolias

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Re: Can’t get Probe to Work
« Reply #18 on: March 02, 2016, 08:35:17 AM »
Not sure which ground to connect stirling. My BOB has one ground next to the power IN connectors. Is it ok to connect there or better to take it to my 120VAC earth ground?
Nicolas

Offline stirling

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Re: Can’t get Probe to Work
« Reply #19 on: March 02, 2016, 08:44:35 AM »
the one on the 3 screw power connector is fine or there's a couple more opposite on the 6 screw output connector.