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====== Jog from PLC ======

//Note: This article is an extension of the original [[plc:plc#jog_from_plc|PLC: Jog from PLC]] section. For more info on PLC programming, see the original article.// 

The Jog from PLC feature in myCNC allows motion control commands to be executed directly from within PLC programs.  
This enables dynamic axis control (changing direction, speed, or enabling/disabling movement) without stopping machine motion. Such functionality is especially useful for multi-axis homing or probing operations.

Jogging motion is managed using the following global variables, which define acceleration, speed, and direction.

^ Variable Name              ^ ID    ^ Description ^
| GVAR_G0PLC_SPEED           | 8630  | Jog feedrate |
| GVAR_G0PLC_TIME            | 8631  | Jog acceleration time in ms |
| GVAR_G0PLC_SPEED_UNITS     | 8632  | Jog speed |
| GVAR_PLC_JOGSPEED_UNITS    | 8634  | Jog speed + axis mask (%%axis << 24 | speed%%) |
| GVAR_PLC_JOG               | 8635  | Jog direction control bitmask |

----

===== Example Implementations =====

==== Example 1: X-Axis Homing ====

<code c>
#include pins.h
#include func_homing.h


main()
{
  gvarset(5539,1); //switch to fast g0moveA implementation 
  gvarset(8631,10); //acceleration time 100ms = 0.1s       
  speed=1000;
  gvarset(8634,((1<<24)|speed)); //Jog speed for X
  gvarset(8634,((2<<24)|speed)); //Jog speed for Y
 
  forward=1;
  backward=(1<<8);
  sensor=INPUT_HOME_X;

  probe();
  exit(99);
}
</code>

This PLC:
  * Performs homing along the X-axis.
  * Enables fast motion mode (%%GVAR 5539%%).
  * Sets acceleration time (%%GVAR 8631%%) and jog speed (%%GVAR 8634%%).
  * Defines direction bits for X-axis (%%forward%% / %%backward%%).
  * Uses %%INPUT_HOME_X%% as the active home sensor.
  * Calls the %%probe()%% routine to move toward and retract from the home switch (see the func_homing.h code below).

----

==== Example 2: Y-Axis Homing ====

<code c>
#include pins.h
#include func_homing.h

main()
{
  gvarset(5539,1); //switch to fast g0moveA implementation 
  gvarset(8631,10); //acceleration time 100ms = 0.1s       
  speed=1000;
  gvarset(8634,((1<<24)|speed)); //Jog speed for X
  gvarset(8634,((2<<24)|speed)); //Jog speed for Y
 
  forward=(2<<8);
  backward=2;
  sensor=INPUT_HOME_Y;

  probe();
  exit(99);
}
</code>

  * Performs homing along the Y-axis.
  * Uses same motion parameters as the X-axis script above.
  * Reads the Y home sensor (%%INPUT_HOME_Y%%).

----

==== Example 3: Simultaneous XY Homing ====

<code c>
#include pins.h
#include func_homing.h

main()
{
  gvarset(5539,1); //switch to fast g0moveA implementation 
  gvarset(8631,10); //acceleration time 100ms = 0.1s       
  speed=1000;
  gvarset(8634,((1<<24)|speed)); //Jog speed for X
  gvarset(8634,((2<<24)|speed)); //Jog speed for Y
 
  forward1=1;
  forward2=2;
  backward1=(1<<8);
  backward2=(2<<8);

  sensor1=INPUT_HOME_X;
  sensor2=INPUT_HOME_Y;

  probe_xy();
  exit(99);
}
</code>

  * Performs simultaneous homing of X and Y axes.
  * Defines independent direction masks for each axis.
  * Uses both X and Y home sensors.
  * Calls %%probe_xy()%% to handle dual-axis probing until both sensors are reached.

----

==== Example 4: Probe and Jog Control Functions (func_homing) ====

<code c func_homing.h>
probe()
{
 gvarset(8635,forward); //Jog forward
 timer=60000;
 do
  {
     timer--;
     if ((timer&0xff)==0)  {    gvarset(8635,forward);   };
     a=portget(sensor);
     if (a!=0) { timer=0;};
   }while(timer>0);

 gvarset(8634,((1<<24)|(speed/8))); //Jog speed for X
 gvarset(8634,((2<<24)|(speed/8))); //Jog speed for Y
 gvarset(8635,backward); //Jog backward

 timer=60000;
 do
  {
     timer--;
     if ((timer&0xff)==0)  {    gvarset(8635,backward);   };
     a=portget(sensor);
     if (a==0) { timer=0;};
   }while(timer>0);

  gvarset(8635, 0); //Jog Stop
  do{ a=gvarget(6060); }while(a!=0x4d);
}; 


probe_xy()
{
 dir1=forward1;
 dir2=forward2;
 gvarset(8635,dir1|dir2); //Jog forward
 timer=60000; 
 do
  { 
     timer--;
     if ((timer&0xff)==0)   {       gvarset(8635,dir1|dir2);    };
      if (dir1)
      {
       a=portget(sensor1);
       if (a!=0)
        {
          dir1=0;
          gvarset(8635,dir1|dir2); //Jog forward
        };
      };

      if (dir2)
      {
       a=portget(sensor2);
       if (a!=0)   
        {    
          dir2=0;
          gvarset(8635,dir1|dir2); //Jog forward
        };
      };
   }while(dir1|dir2);

dir1=backward1;
dir2=backward2;

 gvarset(8634,((1<<24)|(speed/8))); //Jog speed for X
 gvarset(8634,((2<<24)|(speed/8))); //Jog speed for Y
 gvarset(8635,dir1|dir2); //Jog backward

 timer=60000;
 do
  {
     timer--;
     if ((timer&0xff)==0)   {       gvarset(8635,dir1|dir2);    };
      if (dir1)
      {
       a=portget(sensor1);
       if (a==0)
        {
          dir1=0;
          gvarset(8635,dir1|dir2); //Jog forward
        };
      };

      if (dir2)
      {
       a=portget(sensor2);
       if (a==0)
        {
          dir2=0;
          gvarset(8635,dir1|dir2); //Jog forward
        };
      };
   }while(dir1|dir2);

  gvarset(8635, 0); //Jog Stop
  do{ a=gvarget(6060); }while(a!=0x4d);
}; 
</code>


**%%probe()%%**
  * Sends a forward jog command.
  * Monitors the assigned input sensor until triggered.
  * Reduces jog speed (1/8 of initial) and reverses.
  * Moves backward until sensor deactivates.
  * Stops jogging and waits for motion completion (%%GVAR 6060 == 0x4D%%).

**%%probe_xy()%%**
  * Executes dual-axis jog for X and Y simultaneously.
  * Each axis stops independently when its home sensor triggers.
  * Once both sensors are active, machine jogs backward at reduced speed until both are clear.
  * Ends motion and waits for confirmation of stop.


The Jog from PLC mode allows smooth and flexible axis control without halting motion or interrupting the main program execution.