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Author Topic: Twitchy MPG  (Read 3348 times)

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Twitchy MPG
« on: October 26, 2011, 07:26:18 PM »
Hello all. I just hooked up a new handwheel control. It has an MPG, axis select and increment select switches. I used the 24vdc that I run throughout the machine for all my inputs and outputs, for the switches in the handwheel. Once I got the new handwheel hooked up, I tested the MPG and it worked great.. but when I move the axis and or increment switches I see a little jump in the handwheel counts. Obviously I have some voltage bleed over.

The coiled cable (prob. 6 feet unwound) that is connected to the handwheel (encoder and switch wires) is shielded and grounded to the machine through the cannon plug. I then have the wires separate into encoder wires (A+/-,B+/-, 5v and gnd) and the wires for my switches. From the split I run the encoder wires through a shielded cable to my motion control card and ground the shield at the motion control card.

I'm thinking that I'm getting the voltage bleed in the handwheel itself. My question is should I drop the voltage to 12v for the switches? Will this do any good?


Thanks for the help :)

Aero

Online BR549

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Re: Twitchy MPG
« Reply #1 on: October 26, 2011, 07:33:08 PM »
What motion control board are you running????

(;-) TP
Re: Twitchy MPG
« Reply #2 on: October 26, 2011, 07:47:55 PM »
What motion control board are you running????

(;-) TP


Sorry, it is a DSPMC from Vital Systems. I run all my INPUTs and OUTPUTs through OPTO 22 relays.

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Re: Twitchy MPG
« Reply #3 on: October 26, 2011, 09:53:36 PM »
YOU really need to get with them to discuss your problems. We have no way of knowing HOW they interfaced their system to MACH3. It is like comparing apples to pineapples. SOunds close but comes from opposite ends of the world.

Most of what applies to the nornal Mach3 may not even applied to the way they wrote the plugin.

There IS a section for that controller here at this site . I would try there to see if you can get help.

(;-) TP
« Last Edit: October 26, 2011, 09:56:31 PM by BR549 »
Re: Twitchy MPG
« Reply #4 on: October 27, 2011, 11:21:03 AM »
Will this isn't really a Vital Systems issue, it's a me trying to figure out how to wire this issue :P I will try to explain how I have this hooked up better ;)

I have my switches (INPUTS) ran to OPTO 22 relays (G4IDC5, that's 10-30v in and 5v ttl out), and I get the power for the switches from the machines 24vdc power supply. From there they enter the motion control card (via 5v ttl).

The encoder (MPG handwheel) is a single-end (A,B) encoder. I have purchased an encoder converter from US Digital that converts the single-end to a differential signal (A+/-, B+/-).

The handwheel itself is integrated (meaning that the encoder (MPG) and the switches are on one card within the handwheel). In the wiring diagram (all in Japaneses) I can see that the switches share a COM. I have hooked 24vdc to that COM for the switches. When the switches are turned they make contact and send 24vdc to my OPTO relay which in turn forces the relay to send the proper 5vdc TTL to the motion control card triggering the INPUT in Mach3.

My question is since the switches and the MPG are integrated inside the handwheel should I be sending 24vdc through the switches? Should I try to lower the voltage or revers the polarity and make the switch go to ground to trigger the relay instead of sending the 24vdc from the switch to the relay?


Thanks :)
Re: Twitchy MPG
« Reply #5 on: October 27, 2011, 12:38:08 PM »
I switch the polarity of the relays, so instead of 24vdc going through the switch it is grounding the relay. Works perfect now.



Thanks for the help :)
Re: Twitchy MPG
« Reply #6 on: October 28, 2011, 11:48:58 AM »
OK now I have a new prob. with the MPG. When I have the servos enabled and the handwheel on, I get extra counts on my MPG, I'm assuming it's noise. Is there a filter I can install to help with this? I have all my cables shielded for encoder, servo signal cables, and they are ALL grounded to the same terminal block, that is then grounded to the machine (see picture). Is this OK to do, or should they be more isolated?


Any help would be great!!

Thanks,

Aero
Re: Twitchy MPG
« Reply #7 on: October 28, 2011, 12:16:34 PM »
You might try a .1 or .01 ceramic capacitor on the MPG input to ground.  I use them and never a noise problem, even with unshielded wiring.

There is also a debounce setting you can increase that may help as well.

BTW, nice control box.

Regards,
John Champlain
www.picengrave.com
Re: Twitchy MPG
« Reply #8 on: October 28, 2011, 03:59:29 PM »
OK I got the capacitors, do I put them as close to the MPG as possible?



Thanks for the help,


Aero

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Re: Twitchy MPG
« Reply #9 on: October 28, 2011, 04:21:52 PM »
Usually on the inputs.
Hood