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\layout Chapter

VCP
\layout Section

VCP: A small example
\layout Standard

NOTE: VCP is deprecated, and will most likely not be getting any new development
 or additional widgets.
 We strongly recommend using pyVCP.
 However, pyVCP won't be released until version 2.2 comes out, and VCP is
 in version 2.1.
 That means some people will wind up using VCP, so we can't simply drop
 it.
\begin_inset Foot
collapsed false

\layout Standard

A .vcp to .xml translator that takes a vcp file and turns it into one that
 pyVCP can use is on my to-do list.
 That would enable VCP users to easily switch over to pyVCP.
 If such a translator is written, VCP may be removed from the version 2.2
 release.
\end_inset 


\layout Standard

Place the following in the file 
\family typewriter 
tiny.vcp
\family default 
:
\layout LyX-Code

vcp { 
\newline 
 main-window { 
\newline 
   box { 
\newline 
     button { 
\newline 
       halpin = vcp.pushbutton 
\newline 
       label { text = "Push Me" } 
\newline 
     } 
\newline 
     LED { 
\newline 
       halpin = vcp.light 
\newline 
     } 
\newline 
   } 
\newline 
 }
\newline 
}
\layout Standard

The above file describes a tiny Virtual Control Panel, with one push button,
 and one light.
 To see what it looks like, we need to start HAL:
\layout LyX-Code

$
\series bold 
 halrun
\layout Standard

Next we load halvcp, and give it the name of our .vcp file:
\layout LyX-Code

halcmd: 
\series bold 
loadusr halvcp tiny.vcp
\series default 

\newline 
halcmd:
\layout Standard

There may be some text printed as halvcp parses the tiny.vcp file, but when
 it finishes, there should be a small window on your screen, with a button
 and an LED.
 It will look something like figure 
\begin_inset LatexCommand \ref{fig:tiny.vpc_onscreen}

\end_inset 

.
\layout Standard


\begin_inset Float figure
wide false
collapsed false

\layout Standard
\align center 

\begin_inset Graphics
	filename tinyvcp.png
	rotateOrigin center

\end_inset 


\layout Caption


\begin_inset LatexCommand \label{fig:tiny.vpc_onscreen}

\end_inset 

tiny.vcp on the screen
\end_inset 


\layout Standard

So, we have a button and an LED, but they aren't connected to anything,
 so nothing happens when you push the button.
 However, the LED and the button both have HAL pins associated with them:
\layout LyX-Code

halcmd: 
\series bold 
show pin
\layout LyX-Code

Component Pins:
\newline 
Owner  Type  Dir     Value      Name
\newline 
 03    bit   IN      FALSE      vcp.light
\newline 
 03    bit   OUT     FALSE      vcp.pushbutton
\newline 
halcmd:
\layout Standard

To make something happen, we can connect a HAL signal between the button
 and the light:
\layout LyX-Code

halcmd
\series bold 
:
\series default 
 
\series bold 
newsig jumper bit
\newline 

\series default 
halcmd:
\series bold 
 linksp jumper vcp.pushbutton
\newline 

\series default 
halcmd:
\series bold 
 linksp jumper vcp.light
\newline 

\series default 
halcmd:
\series bold 
 show sig
\newline 

\series default 
Signals:
\newline 
Type      Value      Name
\newline 
bit       FALSE      jumper
\newline 
                         ==> vcp.light
\newline 
                         <== vcp.pushbutton
\newline 
halcmd:
\layout Standard

Now push the button, and the the LED should light up!
\layout Section

VCP: Another small example with EMC
\layout Standard

Place the following in the file 
\family typewriter 
estop.vcp
\family default 
:
\layout LyX-Code

vcp { 
\newline 
   main-window { 
\newline 
      toggle { halpin = vcp.estop } 
\newline 
   }
\newline 
}
\layout Standard

In your .hal file, remove any existing signal linked to 
\family typewriter 
iocontrol.0.emc-enable-in
\family default 
 and add the following lines:
\layout LyX-Code

loadusr -W halvcp estop.vcp
\newline 
newsig estop bit
\newline 
linkps vcp.estop => estop
\newline 
linkps estop => iocontrol.0.emc-enable-in
\layout Standard

Now, when running your machine, the ESTOP button in the GUI is disabled,
 and the ESTOP button in the VCP window is used instead.
\layout Section

VCP Syntax
\layout Subsection

Block
\layout Standard

A block's format is:
\layout LyX-Code


\emph on 
tag
\emph default 
 { 
\emph on 
contents
\emph default 
 }
\layout Standard

The contents can consist of attributes that describe the block, or other
 blocks that nest inside it.
\layout Standard

A attributes format is
\layout LyX-Code


\emph on 
name
\emph default 
 = 
\emph on 
value
\layout Standard

The attribute names that are acceptable for each block depend on the block
 tag, and will be listed later.
\the_end