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.TH THCUD "9" "2023-02-10" "LinuxCNC Documentation" "HAL Component"
.SH NAME

thcud \- Torch Height Control Up/Down Input
.SH SYNOPSIS
.HP
.B loadrt thcud
.SH 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
.br
Parallel Pin 12 <= THC controller Plasma Up
.br
Parallel Pin 13 <= THC controller Plasma Down
.br
Parallel Pin 15  <= Plasma Torch Arc Ok Signal
.br
Parallel Pin 16 => Plasma Torch Start Arc Contacts

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

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



.SH FUNCTIONS
.TP
\fBthcud\fR (requires a floating-point thread)

.SH PINS
.TP
.B thcud.torch-up\fR bit in \fR
Connect to an input pin
.TP
.B thcud.torch-down\fR bit in \fR
Connect to input pin
.TP
.B thcud.current-vel\fR float in \fR
Connect to motion.current-vel
.TP
.B thcud.requested-vel\fR float in \fR
Connect to motion.requested-vel
.TP
.B thcud.torch-on\fR bit in \fR
Connect to spindle.N.on
.TP
.B thcud.arc-ok\fR bit in \fR
Arc Ok from Plasma Torch
.TP
.B thcud.enable\fR bit in \fR
Enable the THC, if not enabled Z position is passed through
.TP
.B thcud.z-pos-in\fR float in \fR
Z Motor Position Command in from axis.n.motor-pos-cmd
.TP
.B thcud.z-pos-out\fR float out \fR
Z Motor Position Command Out
.TP
.B thcud.z-fb-out\fR float out \fR
Z Position Feedback to Axis
.TP
.B thcud.cur-offset\fR float out \fR
The Current Offset
.TP
.B thcud.vel-status\fR bit out \fR
When the THC thinks we are at requested speed
.TP
.B thcud.removing-offset\fR bit out \fR
Pin for testing
.SH PARAMETERS
.TP
.B thcud.velocity-tol\fR float rw \fR
The deviation percent from planned velocity
.TP
.B thcud.correction-vel\fR float rw \fR
The Velocity to move Z to correct
.SH AUTHOR

John Thornton
.SH LICENSE

GPLv2 or greater