component thcud "Torch Height Control Up/Down Input";

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.

Physical Connections typical
paraport.0.pin-12-in <= THC controller Plasma Up 
paraport.0.pin-13-in <= THC controller Plasma Down
parport.0.pin-15-in  <= Plasma Torch Arc Ok Signal
parport.0.pin-16-out => Plasma Torch Start Arc Contacts

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

HAL Motion Connections
thc.requested-vel <= motion.requested-vel
thc.current-vel <= motion.current-vel

Pyvcp Connections
In the xml file you need something like:

<checkbutton>
  <text>"THC Enable"</text>
  <halpin>"thc-enable"</halpin>
</checkbutton>
<spinbox>
  <width>"5"</width>
  <halpin>"vel-tol"</halpin>
  <min_>.01</min_>
  <max_>1</max_>
  <resolution>0.01</resolution>
  <initval>0.2</initval>
  <format>"1.2f"</format>
  <font>("Arial",10)</font>
</spinbox>

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

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

""";
 
author "John Thornton";

license "GPLv2 or greater";

option singleton yes;

// Input Pins
pin in bit torch_up "Connect to an input pin";
pin in bit torch_down "Connect to input pin";
pin in float current_vel "Connect to motion.current-vel";
pin in float requested_vel "Connect to motion.requested-vel";
pin in bit torch_on "Connect to motion.spindle-on";
pin in bit arc_ok "Arc Ok from Plasma Torch";
pin in bit enable "Enable the THC, if not enabled Z position is passed through";
pin in float z_pos_in "Z Motor Position Command in from axis.n.motor-pos-cmd";

// Output Pins
pin out float z_pos_out "Z Motor Position Command Out";
pin out float z_fb_out "Z Position Feedback to Axis";
pin out float cur_offset "The Current Offset";
pin out bit vel_status "When the THC thinks we are at requested speed";
pin out bit removing_offset "Pin for testing";

// Parameters
param rw float velocity_tol "The deviation percent from planned velocity";
param rw float correction_vel "The Velocity to move Z to correct";

// Global Variables
variable float offset;
variable float last_z_in;

function _;

;;

#include "rtapi_math.h"

FUNCTION(_) {
    if(enable){
        float min_velocity = requested_vel -(requested_vel*(1/velocity_tol));
        if(current_vel > 0 && current_vel >= min_velocity){vel_status = 1;}
        else {vel_status =0;}
        
        if(torch_on && arc_ok && vel_status){ // allow correction
            if(torch_down){
                offset -= correction_vel;
            }
            if(torch_up){
                offset += correction_vel;
            }    
            last_z_in = 0;
        }
        if(!torch_on){ // remove any offset
            float z_diff;
            z_diff = z_pos_in - last_z_in;
            if(z_diff > 0 && offset != 0){ // torch is moving up
                removing_offset = 1;
                if(offset > 0){ // positive offset
                    if(offset > z_diff){ // remove some
                        offset -= z_diff;
                    }
                    else {offset = 0;}
                }
                if(offset < 0){ // negative offset
                    if(offset < z_diff){ // remove some
                        offset += z_diff;
                    }
                    else {offset = 0;}
                }
            }
            else {removing_offset = 0;}
            last_z_in = z_pos_in;
        }
        z_pos_out = z_pos_in + offset;
        z_fb_out = z_pos_in; // keep axis motor position fb from being confused
    }
    if(!enable){
        z_pos_out = z_pos_in;
        z_fb_out = z_pos_in; // keep axis motor position fb from being confused
    }
}