= Halui Examples

For any Halui examples to work you need to add the following line
to the {[}HAL{]} section of the ini file.

    HALUI = halui


== Remote Start

To connect a remote program start button to EMC you use the
halui.program.run pin and the halui.mode.auto pin. You have to
insure that it is Ok to run first by using the halui.mode.is-auto
pin. You do this with an and2 component. The following figure shows
how this is done. When the Remote Run Button is pressed it is
connected to both halui.mode.auto and and2.0.in0. If it is ok for
auto mode the pin halui.mode.is-auto will be on. If both the inputs
to the and2.0 component are on the and2.0.out will be on and this
will start the program.

    Remote Start Example

    . 
image::images/remote-start.png[]
    
    

The hal commands needed to accomplish the above are:

    net program-start-btn halui.mode.auto and2.0.in0 <= <your input pin>

    net program-run-ok and2.0.in1 <= halui.mode.is-auto

    net remote-program-run halui.program.run <= and2.0.out


Notice on line one that there are two reader pins, this can also be
split up to two lines like this:

    net program-start-btn halui.mode.auto <= <your input pin>

    net program-start-btn and2.0.in0


== Paused & Resume

This example developed from the need of EMC2 to move a rotary axis
when told to do so by another machine. To coordinate between two
control systems using Halui we take advantage of two components of
Halui.


 - halui.program.is-paused

 - halui.program.resume


In your custom.hal file we can add a couple of lines that when
connected to your I/O can tell the other control system that the
program is paused and to resume the program when the other control
system wants EMC2 to resume.

    net ispaused halui.program.is-paused => your out pinnet resume
    halui.program.resume <= your in pin


Your inand out'' pin is what is connected to the other
controller. It could be a parallel port pin or any other pin you
have access to.

How this works is when a M0 is encountered in your g code
halui.program.is-paused goes true. This turns on your outpin so
the other controller knows EMC2 is finished.

To resume the g code the other controller makes your inpin go
true. This will then run the EMC2 g code up to the next M0.

Timing requirements


 - Resume must not be true longer that it takes to run the g code

 - Is Paused must not be on when next resume arrives


Timing issues that could foul up a good plan is when the other
controller sends a resume out and sees the is paused bit on and
thinks that EMC2 was very fast at completing the requested command.
The second issue is the other controller sending out a resume that
is longer than it takes to execute the program.

This could be over come using ClassicLadder to turn on the is
paused bit for a limited amount of time then turning it back off.
Also the resume could be on a one shot or a very short timer.