Servo Wiring and Tuning detailed How To example Mesa 7i77.

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05 Jul 2022 15:52 #246655 by andypugh
Is your PID loop closed?

Can you attach the HAL and iNI files?

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06 Jul 2022 18:08 #246742 by Monkey_boy
I don`t know how to attach my ini files bu,t I have flashed th 6i25 & 7i77 with the 5i25_7i77x2.bit file and tried again. It seems that Pncconf won`t allow you to enter a number of pwm gens, whatever you enter turns to zero and stays that way.
Is there a way of up-dating Pncconf or maybe an earlyier version ?
Any thoughts :-

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06 Jul 2022 18:43 #246746 by PCW
The number of" PWMgens" on a 7I77 is fixed at 6
and not something you need to change.

All that you do with PWMGens (which represent analog outputs)
in pnnconf is to assign them to X,Y,Z etc axis

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06 Jul 2022 20:01 #246754 by JPL

I don`t know how to attach my ini files...
 

To attach files do NOT use quick reply. You have to click "Action" and then select "Reply". You will then see the full editor with the "Attachments" button.

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06 Jul 2022 20:03 #246755 by JPL
... OR click "Go to editor" (Bottom right below the text box) if you are in quick reply mode..

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07 Jul 2022 09:41 #246789 by Monkey_boy
 

File Attachment:

File Name: Lightmc1.hal.txt
File Size:12 KB
 

File Attachment:

File Name: Light_machine.ini
File Size:3 KB


Hi I think I`ve managed to attach my hal and ini files they came from Pncconf as they are because I don`t know how to edit them yet.
 
Attachments:

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09 Jul 2022 23:00 - 09 Jul 2022 23:08 #246990 by smc.collins

Hi I`m relatively new to Linuxcnc but not new to cnc machines.
 I am retrofitting a bench top cnc mill made by the Light Machine Corperation and I am in the process of testing the motors and drives,
the motors are Lifton 24V brushed servo motors with 1000 line quadrature encoders and the drives are Copley Controls 412`s.
My setup is a Mesa 6i25 and a 7i77 controller, I currently have two of the motors and drives setup as a lathe configuration in Pncconf.
The drives are adjusted so that when power is applied the motors are stationary in thier deadband without input, but the moment I connect
the inputs and enable the dirves the motors run away and cause a following error and also you can`t control them using the open loop test 
in Pncconf.
As for tuning I`m possibly doing somthing wrong or there is a hardware problem, my attempt at tuning with the calibration page and 
hal scope I have  set all the perameters to zero and 1000 with any number inbetween and I can`t change anythig all the motors do is run away and cause
a following error whatever setting I try !
Could someone please help and give me an idear of what to try next.
www.actronic-solutions.de/files/actronic/FTPROOT/400ce.pdf   

these are your drives ?  here is how I would approach this, disconnect the motor and put a load resistor across the drive output say 20 ohm , 40 watt, grab one of amazon, something in that neighborhood for size. Enable the drive, measure the voltages across "leave tach connected" Tach, Motor out, speed input, and then if you could I'd like to know the voltage difference between the ground plane of the Servo drive and the 7i77. 
Last edit: 09 Jul 2022 23:08 by smc.collins.

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16 Jul 2022 10:15 #247438 by andypugh
There is something a bit funny with the attached HAL fie, but I think that is probably an artefact of how it was attached.
For example the line
addf pid.z servo-threa
has the d missing from the end. And the x PID gain setup has line-wraps between the [TAG] and VALUE.

However if that was the case in the real HAL file I don't think it would load.

I didn't see anythng obviously very wrong. So the next thing to do is have a look at the pid command, feedback and output using halshow (show hal configuration in the Axis GUI, I am not sure how to launch it in other GUIs but in all cases "halcmd loadusr halshow" at a command prompt will launch it. You need the "watch" tab to see live values.

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20 Jul 2022 10:51 #247829 by Monkey_boy
Hi I have tryed the experiment wit the 100 ohm resistor and I got the following results, with no input voltage and the drive not enabled the x axis had 1.8v across the resistor, and withe the drive enabled the  resistor had 61v across it  wit  0.8v on the input. The z axis had 0.5v not enabled and 61v enabled with 0.225 votts on the input.
You can adjust the volts on the motors by turning the gain pots down, this stops them running away but i can`t seem to get linux to give me a reasonable input volage either by running the program or jogging. I think it might be the 7i77 but  not sure ??
 

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20 Jul 2022 11:08 #247831 by Monkey_boy
P.S What signals do I need to look at in the HAL configuration ?

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