On Mon, 25 Sep 2023, Viesturs L?cis wrote:
Date: Mon, 25 Sep 2023 18:47:03 +0300
From: "[UTF-8] Viesturs L?cis" <[email protected]>
Reply-To: "Enhanced Machine Controller (EMC)"
<[email protected]>
To: "Enhanced Machine Controller (EMC)" <[email protected]>
Subject: [Emc-users] 3 encoders on 7i76E?
Hello!
I am trying to help a guy to sort out config changes for their LinuxCNC machine.
Currently they are running servo motors with step/dir signals and
there is no position feedback to LinuxCNC. They are having some issues
with machining errors and they want to change the config so that
encoder signal from servodrive is fed to LinuxCNC with an intention
that it will improve positioning precision. 7i76E is supposed to be
capable of reading 3 encoders - one for spindle and two for MPG. The
idea is to use these 3 encoders for X and Y axes (it is a gantry
machine with total of 3 joints for XY plane).
The problem is that this line in INI file:
CONFIG="num_encoders=3 num_stepgens=4 sserial_port_0=0xxxxxxx"
Gives an error on LinuxCNC startup and I believe this line to be the crucial:
config.num_encoders = 3, but only 1 are available, not loading the driver
The num-encoders line only applies to quadrature encoders built into the FPGA
(and there is only 1 quadrature encoder in the standard 7I76E firmware)
If you wish to use the MPG encoders, you must use sserial mode 2:
( sserial_port_0=2xxxxxxx ) and the 7i76 mpg encoder hal pins
Do I understand correctly that simple change of firmware is required?
Can someone suggest what would be correct firmware for this?
This is standard
And then one more question - are those inputs for MPG encoders
suitable to read "normal" encoder signal, meaning - are there any
limitations on max pulse frequency the inputs can handle for these 2
encoders?
They are quite limited (to say 40,000 counts per second)
In addition they are single ended only and do not support index
In general they are not recommended for motion applications
and rather just for supporting MPGs
A much better solution is to add a 7I85 or 7I85S
Thanks in advance!
Viesturs
_______________________________________________
Emc-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/emc-users
Peter Wallace
Mesa Electronics
_______________________________________________
Emc-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/emc-users
