Test LinuxCNC without motors and encoders connected

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26 Jun 2019 12:53 #137893 by Peterdeleu
I've just created a Stepconf, and her it works fine!
My not working configuration is a Pncconf

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27 Jun 2019 19:48 #138025 by andypugh
What hardware are you actually using, though?

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27 Jun 2019 23:30 #138049 by Peterdeleu
The PC LinuxCNC:
I'm using the onboard graphic card NVIDIAR GeForce 6150 + nForce 430. The motherboard is a M2NPV-VM ASUS

Mesa hardware:
5I25 - 7i77 and a 7i84

At this moment there's no CNC hardware connected.
Before I rebuild my machine (Biesse Rover 18) I try to find out how LinuxCNC works.
I know already a lot about the wiring of the Biesse and everything is documented.
I will use the LinuxCNC build-in PLC to control the hardware on the machine.
But I want to work save. The machine have very strong servo's, and first I want to understand LinuxCNC before I connect it with the Biesse.
What I did on LinuxCNC is simulating the Home and limit switches, the Estop, ... with buttons connected to the IO's.
I've created virtual buttons on the user interface of LinuxSNS to control the IO's. This will make it possible to wire the machine to the Mesa, and test all the hardware by pressing the virtual buttons. (Spindle on, vacuum cups, spindle down, tools down, ....

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27 Jun 2019 23:35 #138050 by andypugh
Well, just be aware that Stepconf isn't that much help for a Mesa setup.

(It is some help, the INI won't be far off, and all the important files will be created.
The HAL pins will be in the right places, but half the names will be wrong.

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27 Jun 2019 23:43 - 27 Jun 2019 23:47 #138055 by Peterdeleu
I know.
I've used pncconf to start. I've changed already a lot on the INI and Hal.
But I only used Stepconf to verify if my PC, graphic card and LinuxCNC was working fine. It is easier to test the PC hardware with Stepconf, because Pncconf needs encoder inputs before it wants to "simulate" a CNC program.
And the CNC-prgram is running fine with a Stepconf configuration, the preview is not smooth. It "jumps" to the end of a movement instruction. With Stepconf I see a smoot displacement of the tool.
And that is something I want to have solved :)

I haven't found strange things or big unexplainable differences in both configurations (Stepconf vs Pncconf).
The only thing that I think that could be the cause, that is that I don't have encoders connected, and I've put the Ferror parameter on 1000. Otherwise the program will not start...
Last edit: 27 Jun 2019 23:47 by Peterdeleu.

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28 Jun 2019 00:23 #138060 by andypugh

Peterdeleu wrote: With Stepconf I see a smoot displacement of the tool.
And that is something I want to have solved :)


Then that is probably entirely due to the lack of feedback in your earlier config.
So we can ignore the problem. This means that Stepconf was a good test,

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02 Jul 2019 14:58 #138401 by Peterdeleu
Ok, next step :) And I will thank the people who already replied on this post. It is very helpful to me ;)
Thanks to you I have already a lot of answers, and I've dropped some "answers and suggestions" in the freezer, because of lack of knowledge at this time to understand them well ;)

I removed one of the encoders from the CNC machine.
Now I'm able to test the encoders (working range 5 - 15V).
When I measure the output on the 7i77, I only have 4.7 volt.
But it doesn't seems a problem for the encoder. I can see reaction the pins in the "Show Hal Configuration.
When I turn the encoder by hand, I can see that (in my test the X-axis) linuxCNC the movement can see.

Next step is tuning the parameters.
My encoders have a resolution of 500 steps/turn.
The X-as on the machine travels 25 mm/turn. (rough measured)
If I understand well, I need to tune the ENCODER_SCALE parameter.
As far as I know, the ENCODER_SCALE should be 500steps/turn decided by 25mm. Result 20 pulses/mm movement.
After changing the ENCODER_SCALE to 20, and turning the encoder 1 turn, I don't see a correct movement in LinuxCNC.
I only have a nearly good movement it I change the parameter to 100.
That's strange... or is there something that I miss here?

And if you have some time left to explain me the following parameters, I would be very thankful.
I tried to find the answers in the last hours, but it is hard to find the correct explanation.
Some answers are to technical and difficult to understand for me as a starter ;)

DEADBAND = 0.0
MAX_OUTPUT = 0.0
ENCODER_SCALE = 100.0
OUTPUT_SCALE = 10.0
OUTPUT_MIN_LIMIT = -10.0
OUTPUT_MAX_LIMIT = 10.0

What are these parameters?

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02 Jul 2019 15:51 #138404 by Peterdeleu
Quick update...

It looks like the encoders are not functioning well with 4.7V.
So first I have to find out how I can change the 4.7V (comming from the FPGA 5I25 board) to a voltage that the encoder likes (10V)
But if I change the encoder to 10V, what with the outputs of the encoders (to the 7i77).. will they also be 10V, and is this OK for the 7i77 encoder input?

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02 Jul 2019 16:00 #138405 by PCW
Normally you should setup the 7I77 to use external 5V power (as suggested in the manual)

For external 7I77 5V power:

5I25 W2 DOWN
7I77 W5 RIGHT

5V power supplied to 7I77 TB1

Note that 5V encodera should work at 4.7V so I suspect you have some other issues

1. Are the encoder single ended or differential? (how many wires)
2. Are the 7I77 encoder inputs jumpered to match the encoder type?

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02 Jul 2019 16:04 - 02 Jul 2019 16:08 #138406 by PCW

PCW wrote: Normally you should setup the 7I77 to use external 5V power (as suggested in the manual)

For external 7I77 5V power:

5I25 W2 DOWN
7I77 W5 RIGHT

5V power supplied to 7I77 TB1

Note that 5V encoders should work at 4.7V so I suspect you have some other issues

1. Are the encoder single ended or differential? (how many wires)
2. Are the 7I77 encoder inputs jumpered to match the encoder type?


Oops thats what happens when you accidentally hit quote instead of edit...
Last edit: 02 Jul 2019 16:08 by PCW.

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