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Author Topic: AutoZero Plate for Z Axis  (Read 17453 times)

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Offline kolias

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Re: AutoZero Plate for Z Axis
« Reply #30 on: March 04, 2011, 10:28:28 PM »
Give me 5 minutes to get your answers
Nicolas

Offline Sage

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Re: AutoZero Plate for Z Axis
« Reply #31 on: March 04, 2011, 10:32:48 PM »
Take the rest of the night. Not sure where you are but I'm going to bed.

While your at it make a drawing of what you have for the limits. Where the wire starts, check the status of the switch (NO or NC) and where it goes to and any other details.
If you have a meter measure the voltage to ground on the limit switch wire when it's sitting idle (switches NOT activated).

Later

Sage

Offline kolias

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Re: AutoZero Plate for Z Axis
« Reply #32 on: March 04, 2011, 11:31:21 PM »
All my limits have contacts for NO, NC & COM and I have wire them between NC and COM. As you can see on the attached BOB, the lowest terminal is the GND and I have connected there all the black wires from the limits. Then on terminal 10 I have the red for the Y axis home & limit switches, on the 11 I have the red from the A axis, on the 12 I have the red from the Z axis and on the 13 I have the red from the X axis. The attached drawing shows how my limits are wired but on this drawing the terminal numbers for each axis are wrong, for some reason I wired them as I describe above

My Inputs screen is as per attached picture. Just to show you the Active Low status

I can put the X axis together with the Z to terminal 12 and thus free up the terminal 13 for the touch plate.

I now get what you mean about the limits and zero setter being used at the same time and I agree.

Sorry but I cant grasp what the active low / high means but if you agree with the above I can put the zero plate on terminal 13 ALONE.

Does it matter if the ground (Black wire) will be together with all black wires from the limits?

I measured the volts between ground and each limit while limits not active and it is 0 volts in all.

Thanks for your time
Nicolas

Offline Sage

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Re: AutoZero Plate for Z Axis
« Reply #33 on: March 04, 2011, 11:56:51 PM »
I'll think about it some more in my sleep.
Active LOW means that the LIMIT condition will be triggered when Mach sees a LOW (ground) on the input (i.e. the condition is ACTIVE when the signal goes LOW)
  It baffles me how this is working now if ,as you say, you have NC switches. If this is ture then all the inputs are LOW already and that should be triggering all the limits. The lights would be on for them in the diagnostics screen.
 Are you sure these are not NO switches. You can test this by pulling the wires off of one of the switches and use an ohmmeter across the connection on the switch from where the wires came. If you measure a short (0 ohms) then you are correct. If there is an open circuit (no meter reaction) then they are in fact NO.

Let me think on it. There is no need to use more than one input for all of the limits and even the home switches, freeing up a lot of inputs. What you do is wire them all in series.

From the BOB input to a switch, from that switch, to the next switch, from that switch to the next etc. etc and finally back to ground on the BOB. The switches have to be all N.C. so the signal can be activated by any one of the switches going open. The setting would be set for ACTIVE HIGH. (the SIGNAL is normally low and is ACTIVATED when it goes HIGH). The high comes from the pull up resistor when the line is no longer pulled low by the switch string.

Sage
« Last Edit: March 05, 2011, 12:00:16 AM by Sage »

Offline Tweakie.CNC

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Re: AutoZero Plate for Z Axis
« Reply #34 on: March 05, 2011, 01:56:24 AM »
Nicolas,

For your probe to work you need a pin that is not being used for anything else.
Connect your X limit switches and Z limit switches in series to pin 11 this will leave pin 10 free.
Now connect your probe to pin 10.

Try that and check if it then works as you would expect it to (I think you will need to slow your probing feedrate as F20 seems a bit fast to me) it would also be a good idea to replace the cutting tool with a piece of metal rod (saves damaging the expensive tool if it does not work correctly).

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline Sage

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Re: AutoZero Plate for Z Axis
« Reply #35 on: March 05, 2011, 08:16:51 AM »
Kolias:
Tweakie is correct. I got onto a bit of a tangent trying to figure out what you have there.  As I also mentioned I don't think it's going to work having the plate and your limits on the same input anyway, so while you're playing with wiring you might as well start now to re-wire things to free up an input.

 Having said that you still need to understand the way the switches are actually wired and the mach settings to fully undestand the ACTIVE LOW or ACTIVE HIGH logic.
 It may be that the BOB is inverting the sense of the actual switch action making it necessary to set the reverse logic in the software.  (is that possible ??) This will make it doubly confusing.

Sage

Offline kolias

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Re: AutoZero Plate for Z Axis
« Reply #36 on: March 05, 2011, 10:33:26 AM »
First I checked my limit switches with my meter and in the NC position that they all are wired I get continuity and when I press the switch lever I get no continuity.

The I switch the zero plate to terminal 13 and I removed the Z axis wire from there and put it together with the X axis wire to terminal 12

Now the digitize LED on the diagnostic screen is OFF and when I touch the plate with the alligator clip the LED comes on.

So far looks ok BUT...... on the inputs screen all active low ticks are red except for the probe which is green. The EStop and the Y /A axis limits when I press the lever on the limit switch are working, I mean I get the message that limit is triggered. But the X / Z limits are not working, when I press the lever on them I get no message like nothing happened.

On the diagnostic screen all LED’s are off.

Another strange thing is that the desktop I use for the CNC is not connected to the web and so I copy the XML file and transfer it to my office laptop to send it to you but when I replaced the existing XML with the one from the desktop Mack changed all the active low red ticks with green ticks. Dont know why

I liked the idea from Tweakie and I removed the bit I had and replaced with some 12 & 10 gauge copper wires I had after I cut them to length as per attached photo.

So now it looks like the zero plate will work but why the X & Z limits dont work. Maybe they dont like been together, maybe the 0.1uF capacitor doesn’t like to have to limits on the same terminal?

I’m waiting for some instructions
Nicolas

Offline Tweakie.CNC

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Re: AutoZero Plate for Z Axis
« Reply #37 on: March 05, 2011, 10:42:23 AM »
You have incorrectly connected the two sets of limit switches in parallel.

Connect them in series.

GND-----switch----switch----switch----switch----PIN 11

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline kolias

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Re: AutoZero Plate for Z Axis
« Reply #38 on: March 05, 2011, 10:58:19 AM »
Thank you Tweakie, I'm going to do that now and post back
Nicolas

Offline Sage

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Re: AutoZero Plate for Z Axis
« Reply #39 on: March 05, 2011, 11:08:43 AM »
Tweakie:

Boy I,m glad you seem to have a clue what he's doing. He's digging into too many things at once for me to keep track.

Kolias:
They key to good troubleshooting is to NOT introduce too many changes at once. I'm not sure what happened with the XML thing but you need to start over, think about what you need, for each input idividually and together an make it so. One small step at a time.
Im thoroughly confused now.

I'll try to digest what you've done and see if I can help further.

Sage
« Last Edit: March 05, 2011, 11:15:01 AM by Sage »