Set up using AMC AB15A100 drives, brushed DC motor Prototrak Plus with Encoders

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06 Dec 2021 15:22 - 13 Jun 2022 18:25 #228440 by new2linux
I would like to offer many thanks to the forum, the moderators and all the members that make this forum so informative. I am working on a basic 2 axes mill that started life as a prototrak plus. This originally used "back EMF" as feedback with A-M-C 12A8 drives
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Last edit: 13 Jun 2022 18:25 by new2linux. Reason: Edit: add diagram

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06 Dec 2021 16:31 #228450 by tommylight
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06 Dec 2021 16:54 - 08 Dec 2021 13:53 #228453 by new2linux
The ability for others, in the future, ease of searching, with the most sincere hope of success. This AxCent model is the most recent A-M-C drive available. This model supports brushed and brushless motors, seems to be a popular replacement if it can be figured out.
Last edit: 08 Dec 2021 13:53 by new2linux.

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10 Dec 2021 19:04 #228797 by new2linux
I have reviewed tommylight's tuning process at this link:
forum.linuxcnc.org/10-advanced-configura...ning-detailed-how-to
and I am very grateful for these instructions about the tuning process, but was stopped at the area describing; slow feed rate to less than 2"/min. & press arrow key as if to move table. I pressed arrow key, no motion or vibration with motor for just a half second then the f-error appeared. I have slowly adjusted POT 1 CW (from full CCW) as to firm up the motor against rotation w/o any change to motor resisting to rotation. I have in addition adjusted the "P" from under 2000 to over 6000 w/o any change to motor resisting to rotation.
Am I clear in my thinking that when I use the HAL conf (the "watch" / show lights referencing "hm2_5i25.0.7i77.0.1.analogena" window) and observe the change of color, this only shows the HAL is correct, this has nothing to do with the wiring of the drive?

Please, I will re-read and review any documents again. All other suggestions are warmly welcomed. Many thanks.

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10 Dec 2021 20:23 #228805 by tommylight
Trying to tune a velocity servo system while the velocity loop is not tuned is useless.
Is the velocity loop closed on the drives, or, do the motors have the tacho connected to the drives?
Fix that first, no LinuxCNC.
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10 Dec 2021 20:32 #228808 by PCW
Those drives use quadrature encoder for velocity feedback.
But, yes, the drives velocity loop needs to be tuned to resist applied torque
independent of LinuxCNC (so not connected to the 7I77 at all for initial tuning)
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10 Dec 2021 21:05 - 15 Dec 2021 16:25 #228817 by new2linux
Many, many thanks, tommylight & PCW!! There is no tacho. I do not believe the velocity loop is closed. I will review velocity loop literature, over the weekend. Many thanks!
After re-reading the 7i77 manual "OPERATION" section: The last 2 sentences talk about shielded twisted pair of wires, with the shield connected at the 7i77 GND end only. With this addition: The drives common or GND signal (position 2 on the AMC drive) should be connected to the 7i77 power GND with separate wire; this is to the GND for the whole electrical panel? There is a separate GND screw on the base of each drive that I use to go to GND also.

In the next paragraph in the 7i77 manual; Servo Enable Outputs "states enable outputs are polarized and can be damaged".

It is for this reason that I am asking for a 2nd opinion in reference to how correct the diagram that I am offering is.

I belief that I have read the manual correctly, the diagram I have provided needs a drive common or signal GND, (position 2 on the AMC drive) to go to the 7i77 power GND with separate wire?

I am assuming (referencing to the 7i77 manual ) that "AIN +" & "AIN -" are "+REF IN" (4 position on P1) & "-REF IN" (5 position on P1) on the AMC drive.

Many thanks for all the help: I pray this diagram is close to correct.

Edit: I have reread a prior post that test (this was specifically in reference to 12A8 drive, not AB15A100) with the SW1-1 to -3 = OFF & SW1-4 to -6 = ON; starting with POT4 at mid point; turning POT 4 to change direction of motor. This is to test if motor direction can be changed, w/o Linuxcnc power up. All the green LED are on the drives, the drives do not runaway, but the motor does not move or change direction (the change in direction is what is required), but will spin by hand. This is the correct way to test the diagram?

Many thanks.
Last edit: 15 Dec 2021 16:25 by new2linux. Reason: Edit: Additional info and 2nd?s

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12 Apr 2022 21:44 - 12 Apr 2022 21:55 #240084 by new2linux
I have been searching for electoral help for a while & hope and pray that this gentleman has that knowledge. My I ask the forum members to give him a warm welcome, a servo electrician/technician who usually works with PLC controlled servos in an industrial environment. It has taken some time for me to find someone who believes he can help with my application, and will be following this posts. After some face to face reviewing the 7i77 manual, motor spec. sheet, AMC data sheet, in addition to the diagram at the top of this post we are un-shore where or how to start.

I have a diagram at this address in a prior post, (this is the only method that worked to copy link) the very last page, at the bottom after PCW offered helped with AMC a12a100 using tachometer feedback.

forum.linuxcnc.org/12-milling/41356-a-m-...totrak-plus?start=90

Can we use this diagram as a starting point?? This is for tachometer feedback; I believe I need to use encoder velocity mode.

Many, many thanks, all suggestions are warmly welcomed.
 
Last edit: 12 Apr 2022 21:55 by new2linux. Reason: spelling

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13 Apr 2022 00:15 #240099 by andypugh
I don't think that you will be using Hall sensor with a DC drive (first pic in this thread) but I think that the encoder connection is correct (as the drive seems to use either encoder velocity or tachometer)

You can probably run the drive open-loop but running with a velocity loop in the drive is likely to be easier to tune.
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13 Apr 2022 13:22 - 13 Apr 2022 13:34 #240144 by new2linux
andypugh, Many thanks for your help!! The encoders are working, they count & are the correct direction. The motor, up to this point, I can't use POT 4 (I believe is the proper POT, with the proper switches at (SW1) in place) to change direction of motor w/o Linuxcnc running. It is the motor, to the 7i77 card, to the driver, wiring diagram I think is the unknown part. It is early now, I have emailed my electrician.
Many thanks for the help!
Last edit: 13 Apr 2022 13:34 by new2linux. Reason: to clearify

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