Differences

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--- plc:plc [2022/10/27 13:41] – ivan
+++ plc:plc [2022/11/07 16:03] (current) – ivan
@@ Line 534: / Line 534: @@
 //**NOTE**: Jog from PLC requires a firmware update. As of February 2022, the feature is available in the Testing firmware branch.//
-myCNC allows the user to call for a jog command from within PLCs. The advantage of this motion mode is that it allows to perform tasks (such as changing the speed and direction of movement, as well as turning the motion for a particular axis on or off), all without stopping. This is useful in such applications as homing along multiple (for example, three) axes. Such an example is available here: [[plc:plc_examples#simultaneous_homing_for_two_axes|PLC Examples]]
+myCNC allows the user to call for a jog command from within PLCs. The advantage of this motion mode is that it allows to perform tasks (such as changing the speed and direction of movement, as well as turning the motion for a particular axis on or off), all without stopping. This is useful in such applications as homing along multiple (for example, three) axes. Such an example (with simultaneous positioning along the X and Y axes) is available here: [[plc:plc_examples#simultaneous_homing_for_two_axes|PLC Examples]]
 In this mode, the acceleration is set via the following command:
@@ Line 605: / Line 605: @@
 | GVAR_PLC_JOGSPEED_UNITS | 8634 |
 | GVAR_PLC_JOG | 8635 |
+An example of a homing PLC that utilized this functionality is shown below. This PLC is designed for the Z-axis only:
+<code C>#include pins.h
+wait_move()
+{
+    do { code=gvarget(6060); }while(code!=0x4d);  //wait till motion finished
+};
+show_error()
+{
+    gvarset(9121,1); //bring up popup message 21 - this can be customized
+    timer=50;do{timer--;}while(timer>0);
+    message=PLCCMD_MOTION_BREAK;	//1033
+    exit(99);
+};
+find_home_z()
+{
+  gvarset(5521,1); //disable hardware limits
+  gvarset(5525,1); //disable software limits
+  gvarset(8631,50); //acceleration time 100ms = 0.05s
+  statez=0; //we set the "triggered" state to 0 by default
+  speed=500;
+  speed_slow=100; //used on rollback for better precision
+  direction=(4<<8); //set the direction variable to Z-
+  gvarset(8634,(4<<24)|speed); //Jog speed for Z
+  gvarset(8635,direction); //jog in the set direction Z-
+  timer=0;
+  do
+   {
+      changed=0;
+      if (statez==0) //to home X
+       {
+          sens=portget(INPUT_HOME_Z); //get state of home x sensor
+          if (sens!=0)
+          {
+            statez=1;
+            gvarset(8634,(4<<24)|speed_slow); //Jog speed for Z
+            changed=1;
+          };
+       };
+      if (statez==1) //rollback from home Z
+       {
+          sens=portget(INPUT_HOME_Z); //receive the state of the sensor
+          if (sens==0)
+          {
+            statez=2;
+            changed=1;
+          };
+       };
+  if (changed!=0) //if any of the sensors state is changed
+  {
+    direction=0; //set direction to 0 (no movement) before flipping
+    if (statez==0) { direction=direction | (4<<8);  };  //direction set to X-
+    if (statez==1) { direction=direction | 4;  }; //direction set to X+
+    gvarset(8635,direction); //jog in new direction for the axes
+  };
+      if ((timer&0xff)==0)   {     gvarset(8635,direction);    };
+      timer++;
+      ready=(statez==2);
+    }while(ready==0);
+   gvarset(8635,0); wait_move(); //stop jog
+};
+main()
+{
+  gvarset(8631,50); //acceleration time 50ms = 0.05s
+  gvarset(5539,1); //switch to fast g0moveA implementation
+  find_home_z();
+  exit(99);  //normal exit
+};</code>
+The PLC above can be combined with the XY homing (linked at the start of this section) to create simultaneous XYZ homing. In general, the Jog from PLC functionality allows for this simultaneous movement, cutting down on the previously required separate procedures per each axis.