NAME

       thcud - Torch Height Control Up/Down Input

SYNOPSIS

       loadrt thcud

DESCRIPTION

       Torch Height Control This THC takes either an up or a down input from a THC

       If  enabled  and torch is on and X + Y velocity is within tolerance of set speed allow the
       THC to offset the Z axis as needed to maintain voltage.

       If enabled and torch is off and the Z axis is moving up remove any correction  at  a  rate
       not to exceed the rate of movement of the Z axis.

       If  enabled  and torch is off and there is no correction pass the Z position and feed back
       untouched.

       If not enabled pass the Z position and feed back untouched.

       Typical Physical Connections using a Parallel Port
       Parallel Pin 12 <= THC controller Plasma Up
       Parallel Pin 13 <= THC controller Plasma Down
       Parallel Pin 15  <= Plasma Torch Arc Ok Signal
       Parallel Pin 16 => Plasma Torch Start Arc Contacts

       HAL Plasma Connections
       net torch-up thcud.torch-up <= parport.0.pin-12-in
       net torch-down thcud.torch-down <= parport.0.pin-13-in
       net torch-on spindle.0.on => parport.0.pin-16-out (start the arc)
       net arc-ok thcud.arc-ok <= motion.digital-in-00 <= parport.0.pin-15-in (arc ok signal)

       HAL Motion Connections
       net requested-vel thcud.requested-vel <= motion.requested-vel
       net current-vel thcud.current-vel <= motion.current-vel

       PyVCP Connections In the XML file you need something like:

         <pyvcp>
         <checkbutton>
           <text>"THC Enable"</text>
           <halpin>"thc-enable"</halpin>
         </checkbutton>
         </pyvcp>

       Connect the PyVCP pins in the postgui.hal file like this:

       net thc-enable thcud.enable <= pyvcp.thc-enable

FUNCTIONS

       thcud (requires a floating-point thread)

PINS

       thcud.torch-up bit in
              Connect to an input pin

       thcud.torch-down bit in
              Connect to input pin

       thcud.current-vel float in
              Connect to motion.current-vel

       thcud.requested-vel float in
              Connect to motion.requested-vel

       thcud.torch-on bit in
              Connect to spindle.N.on

       thcud.arc-ok bit in
              Arc Ok from Plasma Torch

       thcud.enable bit in
              Enable the THC, if not enabled Z position is passed through

       thcud.z-pos-in float in
              Z Motor Position Command in from axis.n.motor-pos-cmd

       thcud.z-pos-out float out
              Z Motor Position Command Out

       thcud.z-fb-out float out
              Z Position Feedback to Axis

       thcud.cur-offset float out
              The Current Offset

       thcud.vel-status bit out
              When the THC thinks we are at requested speed

       thcud.removing-offset bit out
              Pin for testing

PARAMETERS

       thcud.velocity-tol float rw
              The deviation percent from planned velocity

       thcud.correction-vel float rw
              The Velocity to move Z to correct

AUTHOR

       John Thornton

LICENSE

       GPLv2 or greater