Connect comp param to GUI

ArcEye wrote:

The below works on my simulation

net temp-pid-P <= pid.0.Pgain => pyvcp.temperature-pid-P

Is your pyvcp an output or an input?

I get the same error connecting a simple output pin (from constant) to Pgain.

I get the same error trying to connect a spin box pin to the I/O

John

You can only link I/O type pins to inputs, or other I/O pins (as only one pin in a net is allowed to be a writer)
As far as I can see there is no good reason for the gain pins to be I/O.

You _might_ find that the machine->calibration screen does what you want, have you tried that?

There are a number of inelegant solutions:
1) Change the pin type in /usr/share/pyshared/pyvcp_widgets.py
Possibly better to copy and paste the spinbox control name into a widget with a new name.
The magic value is on line 800 (if you are using a spinbox), change HAL_OUT to HAL_IO
This is a runtime-interpreted file, so there should be no need to recompile anything.

2) Edit and recompile pid.c You will need the file to do this (you could pick up just that one file from git.linuxcnc.org, it's in src/hal/components
You can recompile and install using comp, without needing to reinstall all of EMC2.
In some ways this it the tidiest option.

3) create a very simple HAL module with an IN pin and an IO pin, and a function that make out = in.
Again, that would need to be compiled with comp.

Now we have spotted this problem we might change those pins to inputs in the next EMC2 release. Nobody I have talked to so far thinks that makes any sense.