MPG and MESA 7i76E

27 Feb 2024 01:00 #294566 by ajc771
MPG and MESA 7i76E was created by ajc771

I have a Differential MPG on my Pendant control (It has A+, A-,B+,B- and 5V and GND)  and because of the distance to the 7i76e card and the noise,  I would like to use this 100 turn encoder in the differential mode.   With the 7i76e in mode 2 there are two MPG possible on terminal 16 &17 and terminals 18 & 19.  Is there a way to connect one MPG in the differential mode on these terminals?   If so, exactly where and how would I connect them?  Also, is there any special lines I would have to add to my HAL file or INI file?



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27 Feb 2024 02:44 #294571 by PCW
Replied by PCW on topic MPG and MESA 7i76E
There is no way to use the 7I76E MPG inputs differentially
but typically MPG inputs are pretty slow so if you had
a noise issue you could just add a bit of RC filtering.
(or add a differential receiver chip like a 26LS32)

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27 Feb 2024 07:01 #294580 by ajc771
Replied by ajc771 on topic MPG and MESA 7i76E
Hi Peter;

Thanks, I will look into that receiver chip.

Just for others who might find problems getting their MPG to work; I had to make some modifications to the HAL file. (I am using LinuxCNC 2.9.2)

1) I decided to use the jog-vel-mode 1 over incremental because I was use to a VMC I used at my job that would Jog that way: For each axis I did:

setp axis.x.jog-vel-mode 1
setp axis.y.jog-vel-mode 1
setp axis.z.jog-vel-mode 1

Mode 1 does not need increment but jogs each axis (selected by a switch on the Pendant Control) continuously at the speed of the turning of the encoder wheel.

2) Next I had to add this line for the motion module:

net motion-in-position halui.mode.teleop hm2_7i76e.0.7i76.0.0.input-07

3) For each Axis x,y &z I:

setp axis.x.jog-scale 3 #(to lower the speed I could have put 0.5 for example)
net axis-select-x => axis.x.jog-enable
net axis-selected-count => axis.x.jog-counts

Input 7, above, is an input pin on my MESA card that is netted to a switch on the Pendant control. I also had to comment out all the places in the HAL file that had to do with incremental control. The pedant control and the MPG work fine now.

Thanks Again,

The following user(s) said Thank You: tommylight

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