Mesa 7i96 Ethernet board

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10 Oct 2018 20:02 #118655 by Ewok2
Replied by Ewok2 on topic Mesa 7i96 Ethernet board
Wonderfull it work.
The sound is continuous, maybe a litle "high tone" for the X axis....
I can go from the min to the max on each axis.
My last question is :
Do I need to try to tune each parameter ? or I can start to test with a drill now?
For exemple the value :
DIRSETUP = 7500
DIRHOLD = 2000
STEPLEN = 7500
STEPSPACE = 1000
works but do I need to try to put the best value as possible ?
If yes, is there theoritical calculation to do ? Or is it only by test ?

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10 Oct 2018 20:14 - 10 Oct 2018 20:15 #118656 by PCW
Replied by PCW on topic Mesa 7i96 Ethernet board
I would tend to use as long as possible for the step lengths and step space times as long as it does not interfere with the maximum required step pulse rate.

Maximum hardware step pulse rate is 1/(StepLength+StepSpace)
The maximum step rate of the above calculation should be about 25% greater than the machines maximum required step rate so that the feedback control has some working room at the highest machine speed.

I would set the direction setup and hold times quite long, say 20000 ns since this will work for almost any drive and has no real performance penalties.
Last edit: 10 Oct 2018 20:15 by PCW.

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29 Oct 2018 17:22 #119604 by Ewok2
Replied by Ewok2 on topic Mesa 7i96 Ethernet board
Thanks Tommylight.
I change the 12V power supply to a 24V power supply and now the sound is correct when the 3 axis are moving. With 12V I had a horrible noise. You had the feeling that engine where to few powered...

Now PCB, to end with the configuration of the DIRSETUP, DIRHOLD, STEPLEN, STEPSPACE, if I have understand, I set DIRSETUP, DIRHOLD to 20000 ns and I calculate the 2 other with : step pulse rate is 1/(StepLength+StepSpace)
And step pulse rate theorique 25% more than real
=> But how do I calculate the real step pulse rate ?

Do you mean I transform the maximum speed ine mm/s in one axis in step per second ?
but how I know the maximum speed possible on my machine ?

Many thanks
and

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29 Oct 2018 18:39 #119605 by PCW
Replied by PCW on topic Mesa 7i96 Ethernet board
Typically the maximum speed is determined by your step motors, stepdrives, power supply voltage, and the mechanical load the stepmotors are driving.

Stepmotors lose torque rapidly as speed increases and at some point will stall during acceleration or with combined acceleration and cutting loads. To avoid stalling you need to keep the velocity and acceleration limited to a fair amount below the motors (velocity dependent) torque limits.

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29 Oct 2018 19:09 #119607 by Ewok2
Replied by Ewok2 on topic Mesa 7i96 Ethernet board
Some more information after some tests :
maximum speed is 3600mm/s so I put it to 3000mm/s
I do not notice any change by passing STEPSPACE from 100 to 10000 ... => I put it to 1000
for STEPLEN below 600 no move, between 600 and 900 bad noise, above 1000 seem's ok.
So I set it to 2000.

Now I will calculate the theoritical value with your formula :-)
Thanks

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29 Oct 2018 19:35 #119610 by Ewok2
Replied by Ewok2 on topic Mesa 7i96 Ethernet board
I should miss something...
let's get max speed to 3000mm/min => 50mm/s
my cinematics give 4mm/360° and my conf give 1600 microstep / 360° => 400step/mm
So I have a max step pulse of 50*400=> 20 000
but how coul a get a 1/(STEPSPACE+STEPLEN) = 20 000 ?

with my current conf STEPLEN = 1us ; STEPSPACE = 2us
I get a rate of 333 333 ...

I should have miss understand something ?

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29 Oct 2018 19:40 - 29 Oct 2018 19:41 #119611 by PCW
Replied by PCW on topic Mesa 7i96 Ethernet board
Yeah the thing I am trying to say is that the limitation will be in your drives and
motors/mechanics not electronic timing.

The timing should just be set so there are sufficient margins.

(double the drive manufacturers minimums is a good rule of thumb for the timing settings)
Last edit: 29 Oct 2018 19:41 by PCW.

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24 Feb 2019 00:05 #127027 by BigDo
Replied by BigDo on topic Mesa 7i96 Ethernet board
is there a difference between 7i76e and 7i96 Card?

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24 Feb 2019 01:19 - 24 Feb 2019 01:20 #127031 by PCW
Replied by PCW on topic Mesa 7i96 Ethernet board
Both have 5 Axis of step/dir + spindle encoder input+ serial expansion

Differences:

7I76E:
32 inputs
16 outputs
analog spindle interface
2 parallel expansion ports
8 to 32V power

7I96:
11 inputs
6 outputs
1 parallel expansion port
5V power
Last edit: 24 Feb 2019 01:20 by PCW.
The following user(s) said Thank You: BigDo

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09 Mar 2019 15:33 #128169 by persei8
Replied by persei8 on topic Mesa 7i96 Ethernet board
This may be more related to OS networking than Mesa card, but if I'm using the ethernet interface for the Mesa card, can I still use a USB wifi dongle to connect to my wifi network for transferring gcode files, etc.? I would like to replace the parport and bob with a 7i96 to get a little more I/O and remove the dependence on jitter performance. While I'm at it, would offloading the motion control to the FPGA allow me to use a lower performance single board computer instead of a desktop unit? Thank you.

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