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TOPIC: touch probe noise

touch probe noise 06 Мар 2012 19:10 #18433

  • whampoo
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Hi All,
I am getting false hits on my probe, I have tried to insert a debounce statement in the HAL.ini file with no luck probably because I have no clue how its supposed to be written. Any help would be appreciated, its set to para pin 13. I tried to edit the file and it stopped EMC from starting up ...

Thanks
Joel
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Re:touch probe noise 07 Мар 2012 01:34 #18438

  • ArcEye
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Hi

You will need something like the below.
I use debounce components on my limits and home switches to get a clean cut off and eliminate line noise and they work well.
loadrt debounce cfg=1
addf debounce.0 base-thread
setp debounce.0.delay 100  # default is 5 which is too short for most things

net probe-raw parport.0.pin-13-in => debounce.0.0.in
net probe-filtered <= debounce.0.0.out   => 'probe-signal-input-pin' 
# ie connect to wherever parport.0.pin-13 was connected before

For further info do man debounce from a terminal or check the html version
linuxcnc.org/docs/2.5/html/man/man9/debounce.9.html

regards
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Re:touch probe noise 07 Мар 2012 02:09 #18439

  • Rick G
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Are you getting false random hits such as from noise or extra hits when you contact/retract from target?

Rick G
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Re:touch probe noise 07 Мар 2012 04:17 #18441

  • whampoo
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Hi all,

Rick, I am getting false random hits from noise, I was raising the z axis and it hit about 6 times before I reached the desired height.
I am hoping to try my first probe test run tonight. :)

Thank you ArcEye I will give that a try. I looked at the debounce page its all still Greek to me. I will eventually understand
it all but for now, I am still to new to EMC and its been many years since I have played with Linux. I will eventually get there if
my brain doesn't quit before then. :S



Thank you all very much.
Joel
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Re:touch probe noise 07 Мар 2012 04:57 #18442

  • BigJohnT
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If your probe wire runs parallel to any hi current wires you might need to use shielded wire with the shield grounded on one end only.

John
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Re:touch probe noise 07 Мар 2012 05:49 #18444

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Hi John,
The wire is shielded, I bought the probe and it using the 1/4" jack with a shielded cable but I also had the same issues with my homing/limit switches and you help me with that a while back. It may be that the BOB is not one of the best and has its own issues and causing noise. It may not be grounded correctly? This is something I am going to look at, sometimes its the simplest things that cause the biggest problems.



Thanks again,
Joel
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Re:touch probe noise 07 Мар 2012 07:23 #18446

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Make sure the shield is only grounded on one end or else you create a current loop instead of a shield drain and bad things happen when you have a current loop...

John
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Re:touch probe noise 08 Мар 2012 21:13 #18470

  • whampoo
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Hi all,

sorry to bother you with this but no matter what I try using the sample code I get errors when I try to start up EMC ... either the pin doesn't exist or its already defines or an unexpected realtime delay on task 1.
I guess I just don't quite get some of this setup stuff yet ... wonder if I ever will :S
here is the Hal file I am using.

#load the debounce. One set of three channels.
loadrt debounce cfg=4


#add the debounce to a thread, so that it gets run
#this is running in the fast base-thread
#you could use the servo thread. I am not sure which would be best.
addf debounce.0 base-thread



#Unlink the parport pins and limit inputs for rewiring
delsig max-home-x
delsig max-home-y
delsig max-home-z


net x-raw parport.0.pin-10-in => debounce.0.0.in
net y-raw parport.0.pin-11-in => debounce.0.1.in
net z-raw parport.0.pin-12-in => debounce.0.2.in
net probe parport.0.pin-13-in => debounce.0.3.in


net x-filt debounce.0.0.out => axis.0.home-sw-in axis.0.pos-lim-sw-in axis.0.neg-lim-sw-in
net y-filt debounce.0.1.out => axis.1.home-sw-in axis.1.pos-lim-sw-in axis.1.neg-lim-sw-in
net z-filt debounce.0.2.out => axis.2.home-sw-in axis.2.pos-lim-sw-in axis.2.neg-lim-sw-in
net probe-filt <= debounce.0.3.out => motion.probe.in


#It's important to actually activate the debounce
#20 base-threads is about 0.4mS. The typical machine doesn't move far in that time.
setp debounce.0.delay 40


Thanks for any help you can provide.
Joel
Last Edit: 08 Мар 2012 21:14 by whampoo. Reason: typo
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Re:touch probe noise 09 Мар 2012 03:15 #18474

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#load the debounce. One set of three channels.
loadrt debounce cfg=4


#add the debounce to a thread, so that it gets run
#this is running in the fast base-thread
#you could use the servo thread. I am not sure which would be best.
addf debounce.0 base-thread

It looks like you are only trying to have one debounce
#addf debounce.0 base-thread

connected to the base thread, you need to connect all four of them.

An example of connected multiple components...
wiki.linuxcnc.org/cgi-bin/wiki.pl?Simple_Remote_Pendant
loadrt or2 count=2
loadrt mux4 count=1

addf or2.0 servo-thread
addf or2.1 servo-thread

Rick G
Last Edit: 09 Мар 2012 03:20 by Rick G.
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Re:touch probe noise 09 Мар 2012 07:07 #18475

  • whampoo
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OK looks like I am just a total moron when it comes to what you typed :huh:

loadrt or2 count=2
loadrt mux4 count=1

addf or2.0 servo-thread
addf or2.1 servo-thread

when I looked up the pendant info it was showing the postgui.hal file does it matter which file I use to make the changes? Even so, now I am reaching here and trying really hard to understand its just not sinking in ... you are saying I don't have enough threads? The other 3 debounce statements stopped the noise issues with the homing switches. Was I just lucky on that and possibly only one of the switched was causing the problem ? I am using the same ground for all 3 switches and the probe as well not sure if this would cause a problem or not. Anyway back to the probe... I see that the probe-in was added to the other configuration files and it does get initialized. are you saying I need to change this statement to:

net probe parport.0.pin-13-in => debounce.1.3.in
net probe-filt <= debounce.1.3.out => motion.probe.in

Sorry I am still quite new at the whole CNC thing ... and not very well versed on how all this stuff seems to work together, and the logic behind just isn't sinking in ..... I guess that is part of the problem of never working with something and then building one to play with, either way, I am really starting to believe the first thing to go is the mind ... or I guess the second..... the eyes have already gone ... so I am well on my way with the mind now ... :laugh:

Thanks
Joel
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