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Author Topic: Encoder Input configuration...what am I missing?  (Read 4112 times)

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Offline B3030

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Encoder Input configuration...what am I missing?
« on: May 13, 2014, 07:01:19 PM »
I have a Sherline mill that I have converted to CNC using a CNC4PC C11 BOB and Mach3.  I sometimes use the mill manually so I've been able to mount the Sherline encoders between the steppers and the handwheels.  I provided +5V power as required, and connected the two quadrature encoder outputs to two of the C11 input pins.  I configured those two pins with pull-up resistors on the board.  I enabled the three encoders on the Ports and Pins/Encoder/MPG's page, and set the correct port and pins.  I have the counts/Unit set to 32 for now but will verify the correct setting.

When I turn the handwheels I see only .0001 movement back and forth on the Settings screen's Encoder Postion DROs.  The C11 BOB has LEDs on each input to indicate the condition.  The LEDs flicker on and off as I turn the encoder...as the should to indicate the pulse trains from the toothed wheel inside the encoder.

I then slaved in a set of cheap VEX robot encoders (to replace the Sherline encoders) and I get the same result on the Encoder Position DRO's.

Is there anything else to configure in Mach3 to get the Encoders working? 

I appreciate any advise.

B3030
Re: Encoder Input configuration...what am I missing?
« Reply #1 on: May 13, 2014, 07:29:36 PM »
From the manual:

The Counts per unit value should be set to correspond to the resolution of the encoder and your selection
of Native units. For example, a linear scale with rulings at 20 microns produces a count every 5
microns (remember the quadrature signal), or 200 counts per unit (millimeter). If you have Native
units set to inches, then it would be 200 x 25.4 = 5080 counts per unit (inch) because there are 25.4
millimeters per inch. The Velocity value is not used.


Russ

Offline B3030

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Re: Encoder Input configuration...what am I missing?
« Reply #2 on: May 13, 2014, 08:46:09 PM »
Overloaded,

Thanks for the reply.

I saw that in the manual but I believe that, unless I'm off a huge amount, would affect only the overall accuracy of the encoder readout.  Even if I have it wrong, it should still count up (or down) either too fast or too slow.  As it it now, the Encoder Position readout just flicks back and forth from .0001 to .0000.

Am I right in my understanding that the only settings that affect the encoder readout are on that Ports and Pins/Encoder/MPG's page?

B3030
Re: Encoder Input configuration...what am I missing?
« Reply #3 on: May 13, 2014, 09:17:54 PM »
Maybe double check the channel A and B wiring.
You may be receiving only one channel.

Offline B3030

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Re: Encoder Input configuration...what am I missing?
« Reply #4 on: May 14, 2014, 07:17:04 AM »
I thought about that too so I disconnected the Sherline encoder and connected a simple VEX quadrature encoder directly to the BOB and got the same results.  The two BOB Input channel LEDs do show the classic quadrature pattern I expected to see. 

B3030
Re: Encoder Input configuration...what am I missing?
« Reply #5 on: May 14, 2014, 07:25:57 AM »
Might try/assign different pins, one might be wacky.

Russ
Re: Encoder Input configuration...what am I missing?
« Reply #6 on: May 14, 2014, 08:00:46 AM »
Using the printer port ?
Check the signal continuity through the cable to the PC for both channels.
One might not be making the trip.
Russ


 

Offline Hood

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Re: Encoder Input configuration...what am I missing?
« Reply #7 on: May 14, 2014, 09:02:40 AM »
If you attach your xml I will have a look at that and see if there are problems with it.
Hood

Offline B3030

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Re: Encoder Input configuration...what am I missing?
« Reply #8 on: May 14, 2014, 11:16:19 AM »
Using the printer port ?
Check the signal continuity through the cable to the PC for both channels.
One might not be making the trip.
Russ

 

Yes.  I will check that when I get home and report back.  I appreciate the suggestion.

B3030

Offline B3030

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Re: Encoder Input configuration...what am I missing?
« Reply #9 on: May 14, 2014, 11:21:19 AM »
If you attach your xml I will have a look at that and see if there are problems with it.
Hood
I will do that.
In the meantime, can you verify that, with the encoders enabled and correct ports and pins set on the Ports and Pins/Encoder/MPG's page and valid signals to and through the PP, I should see the Encoder Position DROs on the SETTINGS page reflect the changes? And that no other set up is required?  I saw a thread about OEMDRO codes for encoders but am not sure if it was relevent.

B3030