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Author Topic: Dust hood  (Read 3349 times)

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Dust hood
« on: April 29, 2019, 12:41:31 PM »
Hello all,

on my router I have a pneumatic dust hood. I have two M codes to activate and deactivate it in G code. Also in screen I've made a button so I can raise and lower it in the middle of the program if I want to. But there is a problem. When I start the program (any program that I have) dust hood is activated but then suddenly the output is deactivated in the middle of the program. Sometimes this happens after a minute, sometimes after 10 minutes. Then I have to push the button to activate it again. Any help would be appreciated.
Here is the codes:

function m101()
   
   inst = mc.mcGetInstance()

   local hSig, rc = mc.mcSignalGetHandle(inst, mc.OSIG_OUTPUT5)
   mc.mcSignalSetState(hSig, 1)
   
end

if (mc.mcInEditor() == 1) then
   m101()
end

----------------------------------------------------


function m102()
   
   inst = mc.mcGetInstance()

   local hSig, rc = mc.mcSignalGetHandle(inst, mc.OSIG_OUTPUT5)
   mc.mcSignalSetState(hSig, 0)
   
end

if (mc.mcInEditor() == 1) then
   m102()
end

-------------------------------------------------------


-- Dust hood button script


inst = mc.mcGetInstance()

local hSig, rc = mc.mcSignalGetHandle(inst, mc.OSIG_OUTPUT5)
local state, rc = mc.mcSignalGetState(hSig)

if state == 1 then
    mc.mcSignalSetState(hSig, 0)
else
    mc.mcSignalSetState(hSig, 1)
end


Regards,
Peter
Re: Dust hood
« Reply #1 on: April 29, 2019, 02:40:24 PM »
Hi,
I would guess that the button script is triggering when it shouldn't.

Try putting a wxMessageBox line of code in the button script, it may well indicate false triggering.

Craig
My wife left with my best friend...
     and I miss him!
Re: Dust hood
« Reply #2 on: May 02, 2019, 02:39:38 AM »
which hardware you use?
 
Re: Dust hood
« Reply #3 on: May 02, 2019, 04:27:52 AM »
Hi,

I'm using ESS (plugin version v233) with C32 board. Mach4 build 4124.

Peter
« Last Edit: May 02, 2019, 04:31:48 AM by peter81 »
Re: Dust hood
« Reply #4 on: May 02, 2019, 07:42:13 AM »
Hi,
I still suspect electrical noise is causing a false trigger event on your input ISIG_INPUT5.

A wxMeesageBox line in your button script would catch it.

On the ESS PinConfig page add some debounce filtering. You might also consider fitting a 100nF capacitor between the
input terminal and 0V at your BoB.

Craig
My wife left with my best friend...
     and I miss him!
Re: Dust hood
« Reply #5 on: May 02, 2019, 02:44:15 PM »
Hi,

today i've tried a wxMessageBox line in my button script and It didnt trigger the output. The message box didn't appeared on the screen. So the next thing I will try is the debounce filtering the next time I'll be in my work shop. Thanks.

Peter
Re: Dust hood
« Reply #6 on: May 02, 2019, 02:58:17 PM »
Hi,
the wxMessageBox is meant to detect if the button script has triggered or not. It does not cause the button to trigger or
in any other way affect the button or its action.

If noise is affecting the input I would expect the button to trigger, as evidenced by the MessageBox, every once and awhile.

If the fault is occurring  but WITHOUT the MessageBox then the fault is not the button input or its scrit.

The purpose of the wxMessagebox is to help you determine whats going on.

Craig
My wife left with my best friend...
     and I miss him!

Offline reuelt

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Re: Dust hood
« Reply #7 on: May 03, 2019, 07:33:11 AM »
Hello all,

on my router I have a pneumatic dust hood. I have two M codes to activate and deactivate it in G code. Also in screen I've made a button so I can raise and lower it in the middle of the program if I want to. But there is a problem. When I start the program (any program that I have) dust hood is activated but then suddenly the output is deactivated in the middle of the program. Sometimes this happens after a minute, sometimes after 10 minutes. Then I have to push the button to activate it again. Any help would be appreciated.


Perhaps try using a 24Volts (higher voltage less affected by noise) Bistable (self-locking) relay (only a short pulse required to switch states).
(see attached)
Will reduce draining of power from the C32 board when dust hood activated.
« Last Edit: May 03, 2019, 07:38:32 AM by reuelt »
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Re: Dust hood
« Reply #8 on: May 03, 2019, 09:18:18 AM »
Hi,

I am using 24V. This setup has been working whithout any problem for 8 years with mach3. If I run my cnc with mach3 the dust hood is working as it should. When run by mach4 I have this problem when output is suddenly turned off.

Peter
Re: Dust hood
« Reply #9 on: May 03, 2019, 04:56:31 PM »
Hi,
the fact that the line of wxMessageBox code does not occur suggests that it is not a software error.

If the dust hood is triggering it is doing so without being instructed to it suggests EMI noise.
Even 24V signaling is subject to noise if the circuit impedance is high.

If for instance the on state current is 100 uA at 24 V for a power of 2.4mW and impedance of 240kOhm. Therefore a noise impulse
averaging 2.4mW could falsely trigger the circuit.

If the on state circuit current is 10mA at 24V for a power of 240mW and impedance of 2.4kOhm then a very much
larger noise impulse, 240mW, is required to trigger the circuit.

A higher signaling voltage does not in itself ensure noise free communication.

Craig
My wife left with my best friend...
     and I miss him!