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Author Topic: Implementing 3 MPG's one for each of X Y and Z Axis  (Read 9152 times)

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Implementing 3 MPG's one for each of X Y and Z Axis
« on: July 20, 2008, 03:58:43 PM »
I need some help on implementing MPG's on a 3 axis Mill. I wish to use 3 quadrature rotary encoders, one per axis, so that I can manually drive any axis from these 'electronic Handwheels' and machine manualy, as well as position/jog the axis manually, while the DRO's keep track of machine movements. I am using MACH-3, on a fast PEntium, with 2 PAR Port cards. I have set the MPG pinouts to place the X axis MPG on LPT1 (addr = 378) and the Y and Z axes on LPT2. I see the pins toggle on the diagnostic screen. Also the signals are clean, 0.15volt to 4.7volt square waves as the encoder is rotated. I have, to start, simply set the Counts/Unit = 5 and Velocity = 100. The encoders are a 256 pulse per rev on A or B outputs.  After all this is set up, when I set the jog mode to MPG, the X axis (via lpt1) jogs fine, at the selected jog step rate, using MPG-1. the encoder supposedly allocated to the Y axis does nothing, while the Z axis encoder moves the Z axis, but in much smaller step increments. This while the (alt-A) selected axis = X. If I use alt-A to cycle through the selected axes, while on Y , the X axis no longer moves, Y still does not move, Z moves, when Z is selected, No axes move.

What I really would like to achieve is to not use only one MPG, and alt-A cycle thru the active axis, but have all axes 'active' and move when the respective MPG encoder is rotated. But I have not found a combination that works yet.
 I have searched all the posts related to MPG issues, but have not found anything there either.

Any advice gladly accepted.

Thanks
JoNoci

Offline Hood

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Re: Implementing 3 MPG's one for each of X Y and Z Axis
« Reply #1 on: July 20, 2008, 04:49:02 PM »
I have never had any more than 1 MPG hooked up, I have a physical button for each axis to select which one the MPG will work on.
 That however is not answering your question :( Have you done the MPG Calibration for each MPG? Often it makes the MPG much better rather than just setting it up on the Encoder/MPG page. You will find the calibration from the Function Configs menu.
Hood
« Last Edit: July 20, 2008, 04:50:53 PM by Hood »

Offline Chaoticone

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Re: Implementing 3 MPG's one for each of X Y and Z Axis
« Reply #2 on: July 20, 2008, 06:49:28 PM »
Each MPG will have to be set to different input pins in config,ports and pins, MPG/Encoders. Then as Hood said, calibrate each MPG. Open your MPG page by hitting the tab key and see if each mpg has the axis selected your trying to control. I have attached a screen shot to help I hope.

Brett
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Re: Implementing 3 MPG's one for each of X Y and Z Axis
« Reply #3 on: July 21, 2008, 03:18:36 AM »
Thanks Brett/Hood. I am getting closer. I did not select/attach the respective MPG's to the respective axes in the 'TAB' screen, so that is why the MPG's were not driving the required axis. That is all OK now. However, the MPG calibration is not working yet, probably because I do not understand the mechanism properly.  I did as follows:

OPen CAL MPG screen
Select MPG-1
select CAL DETENT, and rotate encoder one detent - gives a count of 10 to 12
select CAL MAX SPEED, and rotate encoder quickly - gives a count of around 500 plus
select CAL STEP/VEL TRANS , and rotate encoder from slow accelerating  to very fast, - gives a count of around 500 plus
select CALCULATE, says step done, then SAVE.
Then Select MPG-2 and repeat, Step done, then SAVE.

Now when I select MPG-3, the select button shows a 'dot' in it, but when I select CAL DETENT, or any of the cal buttons, the MPG-3 button is deselected, and MPG-2
becomes the selected encoder. I seem not to be able to cal MPG-3. However, when in ports n pins I set the Counts/Unit and Velocity values to be the same for MPG-3 as for the pre-calibrated MPG-1 and 2, then MPG-3 drives the axis in the same manner, speed, velocity, etc, as MPG-1 and 2.
So, in essence, it all works, except Cal is a little confusing.

Finally, the step size that each axis moves is 0.005mm ( I work in metric) and I seem unable to change this, regardless of the cycle jog step setting in the TAB screen. Maybe this setting only works for the HOTKEY jog modes? That does seem to step at the selected jog step size setting. I also do not see any change in axis movement step size when speeding up the MPG rotational speed - ie, velocity/step size is still a little confusing for me, and I have not been able to gleen much from the manual.

Kind of you all to help!

JoNo

Offline Chaoticone

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Re: Implementing 3 MPG's one for each of X Y and Z Axis
« Reply #4 on: July 22, 2008, 10:40:16 AM »
JoNo, After each sub calculate, hit calculate on the right then save, then do the next sub the same way. 3 clicks for each, 9 clicks total. Let me know how that does.

Brett
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My guard dog is not what you need to worry about!
Re: Implementing 3 MPG's one for each of X Y and Z Axis
« Reply #5 on: July 22, 2008, 01:25:56 PM »
Hi Brett. I tried as you suggested. MPG-1 and MPG-2 calibrate OK, but still when I select MPG-3, as soon as I select any of the calibrate functions, the select on MPG-3 is removed, and MPG-2 appears as selected. I am unable to calibrate MPG-3 at all- as below

" Now when I select MPG-3, the select button shows a 'dot' in it, but when I select CAL DETENT, or any of the cal buttons, the MPG-3 button is deselected, and MPG-2
becomes the selected encoder. I seem not to be able to cal MPG-3. However, when in ports n pins I set the Counts/Unit and Velocity values to be the same for MPG-3 as for the pre-calibrated MPG-1 and 2, then MPG-3 drives the axis in the same manner, speed, velocity, etc, as MPG-1 and 2. "


I have also played further with the velocity modes, but perhaps you can explain what the intent is behind these selections. I understand them to be -

in velocity mode - the axis will move according to the rate at which you rotate the MPG, the faster you rotate, the faster the move is, but in a sort of linear fashion.
in velocity/step mode - the axis will move, for example, at rate 1 for a certain MPG rotational speed, then if the MPG turns 10% faster, the axis moves 20% faster, and if the MPG rotates 20% faster, the axis moves 50% faster, or something to that effect.

I find no difference between the two selected modes for different MPG rotational rates.

Thanks again.
JoNo

Offline Hood

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Re: Implementing 3 MPG's one for each of X Y and Z Axis
« Reply #6 on: July 22, 2008, 03:28:29 PM »
Velocity mode is like you say, axis moves the speed you turn.
 Velocity Step mode was meant to step when turned slowly but when you went through the threshold speed of rotation that you set in the MPG Config it would revert to Velocity mode. It never really worked that well for me and I think others and I was under the impression that it was not really possible for Art to get it working correctly. Maybe it does work better as it has been 3 or more years since I tried it.
 What I have are two buttons on my panel, one chooses Velocity mode and the other chooses Multi Step mode, normally I am in velocity but if I am sneaking up on something to touch off then I will change to MultiStep when I am close.
 Multi step is very similar to step mode but you dont have to pause for a split second between clciks, one thing to watch out for in MultiStep is it can store up the pulses if you are moving too fast and will continue for a distance after you stop rotating. A few seconds working the MPG in MultiStep will soon get you used to it.
Hood
Re: Implementing 3 MPG's one for each of X Y and Z Axis
« Reply #7 on: March 10, 2009, 07:26:12 AM »
I am having problems setting up a Manual Pulse Encoder for the Z axis on a Seig mill using a C11G breakout board and Mach3
I have set the inputs to use Port 1#: Inputs A# 11 and B#13 but I still do not know how to tell Mach3 to use the Z axis.
Can any one help a newbie to CNC?
Eugene

Offline Chaoticone

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Re: Implementing 3 MPG's one for each of X Y and Z Axis
« Reply #8 on: March 10, 2009, 08:29:38 AM »
Open and close your MPG flyout by pressing the tab button. Set the mode to MPG and Select the axis you want your mpg/s to control.

Brett
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My guard dog is not what you need to worry about!
Re: Implementing 3 MPG's one for each of X Y and Z Axis
« Reply #9 on: March 10, 2009, 10:03:49 AM »
Thanks for the info Bret
Eugene.