1  [[cha:halui-examples]]
 2  
 3  = Halui Examples
 4  
 5  For any Halui examples to work you need to add the following line to the [HAL]
 6  section of the ini file.
 7  
 8  ----
 9  HALUI = halui
10  ----
11  
12  [[sec:halui-remote-start]]
13  
14  == Remote Start
15  
16  To connect a remote program start button to LinuxCNC you use the
17  `halui.program.run` pin and the `halui.mode.auto` pin.
18  You have to insure that it is OK to run first by using the
19  `halui.mode.is-auto` pin. You do this with an `and2`
20  component. The following figure shows how this is done.
21  When the Remote Run Button is pressed it is connected to
22  both `halui.mode.auto` and `and2.0.in0`. If it is OK for
23  auto mode the pin `halui.mode.is-auto` will be on.
24  If both the inputs to the `and2.0` component are on the
25  `and2.0.out` will be on and this will start the program.
26  
27  .Remote Start Example
28  image::images/remote-start.png[alt="Remote Start Example"]
29  
30  The hal commands needed to accomplish the above are:
31  
32      net program-start-btn halui.mode.auto and2.0.in0 <= <your input pin>
33      net program-run-ok and2.0.in1 <= halui.mode.is-auto
34      net remote-program-run halui.program.run <= and2.0.out
35  
36  Notice on line one that there are two reader pins, this can also be split
37  up to two lines like this:
38  
39      net program-start-btn halui.mode.auto <= <your input pin>
40      net program-start-btn and2.0.in0
41  
42  == Pause & Resume
43  
44  This example was developed to allow LinuxCNC to move a
45  rotary axis on a signal from an external machine.
46  The coordination between the two systems will be
47  provided by two Halui components:
48  
49   - halui.program.is-paused
50   - halui.program.resume
51  
52  In your customized hal file, add the following
53  two lines that will be connected to your I/O to turn
54  on the program pause or to resume when the external
55  system wants LinuxCNC to continue. 
56  
57      net ispaused halui.program.is paused => "your output pin"
58      net resume halui.program.resume <= "your input pin"
59  
60  Your input and output pins are connected to the pins
61  wired to the other controller. They may be parallel port
62  pins or any other I/O pins that you have access to.
63  
64  This system works in the following way. When an M0 is
65  encountered in your G-code, the `halui.program.is-paused`
66  signal goes true. This turns on your output pin so that
67  the external controller knows that LinuxCNC is paused.
68  
69  To resume the LinuxCNC gcode program, when the external controller
70  is ready it will make its output true. This will signal
71  LinuxCNC that it should resume executing Gcode.
72  
73  Difficulties in timing
74  
75   - The "resume" input return signal should not be
76     longer than the time required to get the g-code
77     running again.
78  
79   - The "is-paused" output should no longer be active
80     by the time the "resume" signal ends.
81  
82  These timing problems could be avoided by using
83  ClassicLadder to activate the "is-paused" output via a
84  monostable timer to deliver one narrow output pulse.
85  The "resume" pulse could also be received via a monostable timer.
86  
87