Configuring axis gui "axis radio buttons"

An encoder uses an A and B channel in quadrature. Those are simply those two channels being sent to the module that counts encoder pulses from the parallel port.

It is entirely possible to make the push-button of the encoder set feed-rate to 100%, but it has taken dozens of messages to get this far.

Clive wrote:

Is there a problem with this?

Sorry, it was past midnight and I wasn't really in the mood to think hard.

The relevant pins for spindle-override are:
With a scale of 0.01 it takes 100 counts to move the slider from 0 to 100%.
If you slide it back to zero in the GUI, then another 100 counts (to 200) will move it back to 100%

However, if the ..direct-value pin is set to true then it takes absolute rather than relative counts. If counts is 50 and direct-value is set nothing happens, but then as soon as the counts changes to 51 it will go to 51 x scale = 51%.

So, on button press we need to set counts to 100 and also set direct-value to true.

Setting direct-value is easy, we just connect that pin to whatever input pin is operated by the button press.

But, setting the counts to 100 is a little bit harder. There is a HAL component called mux2 that can help here. It outputs one of two inputs depending in the state of the control input.
linuxcnc.org/docs/2.7/html/man/man9/mux2.9.html
But, rather annoyingly, that has an input and output type of "float" and the counts pin is S32[1]
There is an alternative, "mux-generic" where you can select the data type of the inputs and outputs.
linuxcnc.org/docs/2.7/html/man/man9/mux_generic.9.html
It's a bit more difficult to use, but rather more adaptable.
We need to load it:And then it needs to be added to a realtime thread, otherwise it won't get run. You get the function name from the manpage linked above. Note that it is mux_generic to load the file, but mux-gen in the HAL pins. (because file names can't contain "-")We will use 00 for feed-rate and 01 for spindle-rate
We want it to pass normal counts when not "energised" and 100 counts when "energised"
delete your current lineThen addAnd then make the mux operate at the same time as the direct-value:
If you add that to the HAL file you will find that it almost, but not quite works.
What happens is that the override goes to zero, but as soon as the button is released the slider bounces back to the encoder/potentiometer value. (This is a timing thing, when the counts goes from 100 to the new value that is seen as a delta in the counts from 100 to the real encoder counts, and alters the slider again.)
The answer is to set halui.feed-override.count-enable to 0 for a moment when the apparent counts changes. I am still thinking about the best way to do that. If Halui ran in the servo thread it would be fairly easy, as 1mS delay (one thread interval) would be enough. But it doesn't.



[1] float is "floating point" like 3.1415, it can (approximately) represent any real number. S32 is signed 32-bit integer, representing whole numbers from -2,147,483,648 to +2,147,483,647