<p>Your config looks fine for the most of the definitions that have been compared to the known settings when using a probe.</p>
<p>You should be aware that with <code>#define Z_SAFE_HOMING</code> you define that the sensor is in the middle of the bed, however, the nozzle is then offset from the middle of the bed per the <code>#define X_PROBE_OFFSET_FROM_EXTRUDER -43</code> and <code>#define Y_PROBE_OFFSET_FROM_EXTRUDER -4</code> defined offsets.</p>
<p>So, when <code>G28</code> is commanded, the carriage will move to (110, 110) for the probe  which is displayed as (110 - -43, 110 - -4) = (153, 114) for the nozzle.</p>
<p>So there is nothing wrong with the configuration, it works as it should.</p>

CC BY-SA 4.0
2023-11-15T15:04:04.273Z
Thanks for that. I had the printer in storage for a few years and basically lost track of everything I'd learned previously. Good to know the config is correct. So basically the sensor is not expected to be dead sensor now, the starter Gcode will run it's setup and all is good?
Raynbow
CC BY-SA 4.0
2023-11-15T18:53:07.617Z
@Raynbow You're welcome, but thanking is done through [accepting](https://3dprinting.stackexchange.com/help/someone-answers) and [upvoting (requires at least a 15 rep. though)](https://3dprinting.stackexchange.com/help/privileges/vote-up) answers. Please take the [tour] and read our [help] to find all about where Stack Exchange 3DPrinting is all about. We're all happy to help out! I once started with the Anet A8.
0scar
CC BY-SA 4.0
2023-11-15T14:22:02.197Z
2023-11-15T14:22:02.197Z
0scar
<p>Recently added a probe to my Anet A8 for auto bed levelling, calculations have been added based on position of probe to hotend as required. I'm using Marlin 1.1.9.</p>
<p>When I go into 'Prepare' in the printer settings to select auto home, it doesn't centre on the bed, seems to go to the back right. I presume this should be to the centre of the bed? I can't find where to change this in the config. Note the LCD screen shows X:153, Y:114. Config below.</p>
<pre><code>//============================== Endstop Settings ===========================

// @section homing

// Specify here all the endstop connectors that are connected to any endstop or probe.
// Almost all printers will be using one per axis. Probes will use one or more of the
// extra connectors. Leave undefined any used for non-endstop and non-probe purposes.
#define USE_XMIN_PLUG
#define USE_YMIN_PLUG
#define USE_ZMIN_PLUG
//#define USE_XMAX_PLUG
//#define USE_YMAX_PLUG
//#define USE_ZMAX_PLUG

// Enable pullup for all endstops to prevent a floating state
#define ENDSTOPPULLUPS
#if DISABLED(ENDSTOPPULLUPS)
  // Disable ENDSTOPPULLUPS to set pullups individually
  //#define ENDSTOPPULLUP_XMAX
  //#define ENDSTOPPULLUP_YMAX
  //#define ENDSTOPPULLUP_ZMAX
  //#define ENDSTOPPULLUP_XMIN
  //#define ENDSTOPPULLUP_YMIN
  //#define ENDSTOPPULLUP_ZMIN
  //#define ENDSTOPPULLUP_ZMIN_PROBE
#endif

// Mechanical endstop with COM to ground and NC to Signal uses &quot;false&quot; here (most common setup).
#define X_MIN_ENDSTOP_INVERTING true  // set to true to invert the logic of the endstop.
#define Y_MIN_ENDSTOP_INVERTING true  // set to true to invert the logic of the endstop.
#define Z_MIN_ENDSTOP_INVERTING true  // set to true to invert the logic of the endstop.
#define X_MAX_ENDSTOP_INVERTING false // set to true to invert the logic of the endstop.
#define Y_MAX_ENDSTOP_INVERTING false // set to true to invert the logic of the endstop.
#define Z_MAX_ENDSTOP_INVERTING false // set to true to invert the logic of the endstop.
#define Z_MIN_PROBE_ENDSTOP_INVERTING true  // set to true to invert the logic of the probe.

// Enable this feature if all enabled endstop pins are interrupt-capable.
// This will remove the need to poll the interrupt pins, saving many CPU cycles.
//#define ENDSTOP_INTERRUPTS_FEATURE

/**
 * Endstop Noise Filter
 *
 * Enable this option if endstops falsely trigger due to noise.
 * NOTE: Enabling this feature means adds an error of +/-0.2mm, so homing
 * will end up at a slightly different position on each G28. This will also
 * reduce accuracy of some bed probes.
 * For mechanical switches, the better approach to reduce noise is to install
 * a 100 nanofarads ceramic capacitor in parallel with the switch, making it
 * essentially noise-proof without sacrificing accuracy.
 * This option also increases MCU load when endstops or the probe are enabled.
 * So this is not recommended. USE AT YOUR OWN RISK.
 * (This feature is not required for common micro-switches mounted on PCBs
 * based on the Makerbot design, since they already include the 100nF capacitor.)
 */
//#define ENDSTOP_NOISE_FILTER

//=============================================================================
//============================== Movement Settings ============================
//=============================================================================
// @section motion

/**
 * Default Settings
 *
 * These settings can be reset by M502
 *
 * Note that if EEPROM is enabled, saved values will override these.
 */

/**
 * With this option each E stepper can have its own factors for the
 * following movement settings. If fewer factors are given than the
 * total number of extruders, the last value applies to the rest.
 */
//#define DISTINCT_E_FACTORS

/**
 * Default Axis Steps Per Unit (steps/mm)
 * Override with M92
 *                                      X, Y, Z, E0 [, E1[, E2[, E3[, E4]]]]
 */
#define DEFAULT_AXIS_STEPS_PER_UNIT   { 100, 100, 400, 100 }

/**
 * Default Max Feed Rate (mm/s)
 * Override with M203
 *                                      X, Y, Z, E0 [, E1[, E2[, E3[, E4]]]]
 */
#define DEFAULT_MAX_FEEDRATE          { 400, 400, 8, 50 }

/**
 * Default Max Acceleration (change/s) change = mm/s
 * (Maximum start speed for accelerated moves)
 * Override with M201
 *                                      X, Y, Z, E0 [, E1[, E2[, E3[, E4]]]]
 */
#define DEFAULT_MAX_ACCELERATION      { 2000, 2000, 100, 10000 }

/**
 * Default Acceleration (change/s) change = mm/s
 * Override with M204
 *
 *   M204 P    Acceleration
 *   M204 R    Retract Acceleration
 *   M204 T    Travel Acceleration
 */
#define DEFAULT_ACCELERATION          400     // X, Y, Z and E acceleration for printing moves
#define DEFAULT_RETRACT_ACCELERATION  1000    // E acceleration for retracts
#define DEFAULT_TRAVEL_ACCELERATION   1000    // X, Y, Z acceleration for travel (non printing) moves

/**
 * Default Jerk (mm/s)
 * Override with M205 X Y Z E
 *
 * &quot;Jerk&quot; specifies the minimum speed change that requires acceleration.
 * When changing speed and direction, if the difference is less than the
 * value set here, it may happen instantaneously.
 */
#define DEFAULT_XJERK                 10.0
#define DEFAULT_YJERK                 10.0
#define DEFAULT_ZJERK                  0.3
#define DEFAULT_EJERK                  5.0

/**
 * S-Curve Acceleration
 *
 * This option eliminates vibration during printing by fitting a BÃ©zier
 * curve to move acceleration, producing much smoother direction changes.
 *
 * See https://github.com/synthetos/TinyG/wiki/Jerk-Controlled-Motion-Explained
 */
//#define S_CURVE_ACCELERATION

//===========================================================================
//============================= Z Probe Options =============================
//===========================================================================
// @section probes

//
// See http://marlinfw.org/docs/configuration/probes.html
//

/**
 * Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
 *
 * Enable this option for a probe connected to the Z Min endstop pin.
 */
#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN

/**
 * Z_MIN_PROBE_ENDSTOP
 *
 * Enable this option for a probe connected to any pin except Z-Min.
 * (By default Marlin assumes the Z-Max endstop pin.)
 * To use a custom Z Probe pin, set Z_MIN_PROBE_PIN below.
 *
 *  - The simplest option is to use a free endstop connector.
 *  - Use 5V for powered (usually inductive) sensors.
 *
 *  - RAMPS 1.3/1.4 boards may use the 5V, GND, and Aux4-&gt;D32 pin:
 *    - For simple switches connect...
 *      - normally-closed switches to GND and D32.
 *      - normally-open switches to 5V and D32.
 *
 * WARNING: Setting the wrong pin may have unexpected and potentially
 * disastrous consequences. Use with caution and do your homework.
 *
 */
//#define Z_MIN_PROBE_ENDSTOP

/**
 * Probe Type
 *
 * Allen Key Probes, Servo Probes, Z-Sled Probes, FIX_MOUNTED_PROBE, etc.
 * Activate one of these to use Auto Bed Leveling below.
 */

/**
 * The &quot;Manual Probe&quot; provides a means to do &quot;Auto&quot; Bed Leveling without a probe.
 * Use G29 repeatedly, adjusting the Z height at each point with movement commands
 * or (with LCD_BED_LEVELING) the LCD controller.
 */
//#define PROBE_MANUALLY
//#define MANUAL_PROBE_START_Z 0.2

/**
 * A Fix-Mounted Probe either doesn't deploy or needs manual deployment.
 *   (e.g., an inductive probe or a nozzle-based probe-switch.)
 */
#define FIX_MOUNTED_PROBE

/**
 * Z Servo Probe, such as an endstop switch on a rotating arm.
 */
//#define Z_PROBE_SERVO_NR 0   // Defaults to SERVO 0 connector.
//#define Z_SERVO_ANGLES {70,0}  // Z Servo Deploy and Stow angles

/**
 * The BLTouch probe uses a Hall effect sensor and emulates a servo.
 */
//#define BLTOUCH
#if ENABLED(BLTOUCH)
  //#define BLTOUCH_DELAY 375   // (ms) Enable and increase if needed
#endif

/**
 * Enable one or more of the following if probing seems unreliable.
 * Heaters and/or fans can be disabled during probing to minimize electrical
 * noise. A delay can also be added to allow noise and vibration to settle.
 * These options are most useful for the BLTouch probe, but may also improve
 * readings with inductive probes and piezo sensors.
 */
//#define PROBING_HEATERS_OFF       // Turn heaters off when probing
#if ENABLED(PROBING_HEATERS_OFF)
  //#define WAIT_FOR_BED_HEATER     // Wait for bed to heat back up between probes (to improve accuracy)
#endif
//#define PROBING_FANS_OFF          // Turn fans off when probing
//#define DELAY_BEFORE_PROBING 200  // (ms) To prevent vibrations from triggering piezo sensors

// A probe that is deployed and stowed with a solenoid pin (SOL1_PIN)
//#define SOLENOID_PROBE

// A sled-mounted probe like those designed by Charles Bell.
//#define Z_PROBE_SLED
//#define SLED_DOCKING_OFFSET 5  // The extra distance the X axis must travel to pickup the sled. 0 should be fine but you can push it further if you'd like.

//
// For Z_PROBE_ALLEN_KEY see the Delta example configurations.
//

/**
 *   Z Probe to nozzle (X,Y) offset, relative to (0, 0).
 *   X and Y offsets must be integers.
 *
 *   In the following example the X and Y offsets are both positive:
 *   #define X_PROBE_OFFSET_FROM_EXTRUDER 10
 *   #define Y_PROBE_OFFSET_FROM_EXTRUDER 10
 *
 *      +-- BACK ---+
 *      |           |
 *    L |    (+) P  | R &lt;-- probe (20,20)
 *    E |           | I
 *    F | (-) N (+) | G &lt;-- nozzle (10,10)
 *    T |           | H
 *      |    (-)    | T
 *      |           |
 *      O-- FRONT --+
 *    (0,0)
 */
#define X_PROBE_OFFSET_FROM_EXTRUDER -43
#define Y_PROBE_OFFSET_FROM_EXTRUDER -4
#define Z_PROBE_OFFSET_FROM_EXTRUDER 0
// X offset: -left  +right  [of the nozzle]
// Y offset: -front +behind [the nozzle]
// Z offset: -below +above  [the nozzle]

// Certain types of probes need to stay away from edges
#define MIN_PROBE_EDGE 10

// X and Y axis travel speed (mm/m) between probes
#define XY_PROBE_SPEED 6000

// Feedrate (mm/m) for the first approach when double-probing (MULTIPLE_PROBING == 2)
#define Z_PROBE_SPEED_FAST HOMING_FEEDRATE_Z

// Feedrate (mm/m) for the &quot;accurate&quot; probe of each point
#define Z_PROBE_SPEED_SLOW (Z_PROBE_SPEED_FAST / 2)

// The number of probes to perform at each point.
//   Set to 2 for a fast/slow probe, using the second probe result.
//   Set to 3 or more for slow probes, averaging the results.
#define MULTIPLE_PROBING 3

/**
 * Z probes require clearance when deploying, stowing, and moving between
 * probe points to avoid hitting the bed and other hardware.
 * Servo-mounted probes require extra space for the arm to rotate.
 * Inductive probes need space to keep from triggering early.
 *
 * Use these settings to specify the distance (mm) to raise the probe (or
 * lower the bed). The values set here apply over and above any (negative)
 * probe Z Offset set with Z_PROBE_OFFSET_FROM_EXTRUDER, M851, or the LCD.
 * Only integer values &gt;= 1 are valid here.
 *
 * Example: `M851 Z-5` with a CLEARANCE of 4  =&gt;  9mm from bed to nozzle.
 *     But: `M851 Z+1` with a CLEARANCE of 2  =&gt;  2mm from bed to nozzle.
 */
#define Z_CLEARANCE_DEPLOY_PROBE   10 // Z Clearance for Deploy/Stow
#define Z_CLEARANCE_BETWEEN_PROBES  5 // Z Clearance between probe points
#define Z_CLEARANCE_MULTI_PROBE     5 // Z Clearance between multiple probes
//#define Z_AFTER_PROBING           5 // Z position after probing is done

#define Z_PROBE_LOW_POINT          -2 // Farthest distance below the trigger-point to go before stopping

// For M851 give a range for adjusting the Z probe offset
#define Z_PROBE_OFFSET_RANGE_MIN -20
#define Z_PROBE_OFFSET_RANGE_MAX 20

// Enable the M48 repeatability test to test probe accuracy
//#define Z_MIN_PROBE_REPEATABILITY_TEST

// For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
// :{ 0:'Low', 1:'High' }
#define X_ENABLE_ON 0
#define Y_ENABLE_ON 0
#define Z_ENABLE_ON 0
#define E_ENABLE_ON 0 // For all extruders

// Disables axis stepper immediately when it's not being used.
// WARNING: When motors turn off there is a chance of losing position accuracy!
#define DISABLE_X false
#define DISABLE_Y false
#define DISABLE_Z false
// Warn on display about possibly reduced accuracy
//#define DISABLE_REDUCED_ACCURACY_WARNING

// @section extruder

#define DISABLE_E false // For all extruders
#define DISABLE_INACTIVE_EXTRUDER true // Keep only the active extruder enabled.

// @section machine

// Invert the stepper direction. Change (or reverse the motor connector) if an axis goes the wrong way.
#define INVERT_X_DIR false
#define INVERT_Y_DIR false
#define INVERT_Z_DIR true

// @section extruder

// For direct drive extruder v9 set to true, for geared extruder set to false.
#define INVERT_E0_DIR false
#define INVERT_E1_DIR false
#define INVERT_E2_DIR false
#define INVERT_E3_DIR false
#define INVERT_E4_DIR false

// @section homing

//#define NO_MOTION_BEFORE_HOMING  // Inhibit movement until all axes have been homed

//#define UNKNOWN_Z_NO_RAISE // Don't raise Z (lower the bed) if Z is &quot;unknown.&quot; For beds that fall when Z is powered off.

//#define Z_HOMING_HEIGHT 4  // (in mm) Minimal z height before homing (G28) for Z clearance above the bed, clamps, ...
                             // Be sure you have this distance over your Z_MAX_POS in case.

// Direction of endstops when homing; 1=MAX, -1=MIN
// :[-1,1]
#define X_HOME_DIR -1
#define Y_HOME_DIR -1
#define Z_HOME_DIR -1

// @section machine

// The size of the print bed
#define X_BED_SIZE 220
#define Y_BED_SIZE 220

// Travel limits (mm) after homing, corresponding to endstop positions.
#define X_MIN_POS -33
#define Y_MIN_POS -10
#define Z_MIN_POS 0
#define X_MAX_POS X_BED_SIZE
#define Y_MAX_POS Y_BED_SIZE
#define Z_MAX_POS 240

/**
 * Software Endstops
 *
 * - Prevent moves outside the set machine bounds.
 * - Individual axes can be disabled, if desired.
 * - X and Y only apply to Cartesian robots.
 * - Use 'M211' to set software endstops on/off or report current state
 */

// Min software endstops constrain movement within minimum coordinate bounds
#define MIN_SOFTWARE_ENDSTOPS
#if ENABLED(MIN_SOFTWARE_ENDSTOPS)
  #define MIN_SOFTWARE_ENDSTOP_X
  #define MIN_SOFTWARE_ENDSTOP_Y
  #define MIN_SOFTWARE_ENDSTOP_Z
#endif

// Max software endstops constrain movement within maximum coordinate bounds
#define MAX_SOFTWARE_ENDSTOPS
#if ENABLED(MAX_SOFTWARE_ENDSTOPS)
  #define MAX_SOFTWARE_ENDSTOP_X
  #define MAX_SOFTWARE_ENDSTOP_Y
  #define MAX_SOFTWARE_ENDSTOP_Z
#endif

#if ENABLED(MIN_SOFTWARE_ENDSTOPS) || ENABLED(MAX_SOFTWARE_ENDSTOPS)
  //#define SOFT_ENDSTOPS_MENU_ITEM  // Enable/Disable software endstops from the LCD
#endif

/**
 * Filament Runout Sensors
 * Mechanical or opto endstops are used to check for the presence of filament.
 *
 * RAMPS-based boards use SERVO3_PIN for the first runout sensor.
 * For other boards you may need to define FIL_RUNOUT_PIN, FIL_RUNOUT2_PIN, etc.
 * By default the firmware assumes HIGH=FILAMENT PRESENT.
 */
//#define FILAMENT_RUNOUT_SENSOR
#if ENABLED(FILAMENT_RUNOUT_SENSOR)
  #define NUM_RUNOUT_SENSORS   1     // Number of sensors, up to one per extruder. Define a FIL_RUNOUT#_PIN for each.
  #define FIL_RUNOUT_INVERTING false // set to true to invert the logic of the sensor.
  #define FIL_RUNOUT_PULLUP          // Use internal pullup for filament runout pins.
  #define FILAMENT_RUNOUT_SCRIPT &quot;M600&quot;
#endif

//===========================================================================
//=============================== Bed Leveling ==============================
//===========================================================================
// @section calibrate

/**
 * Choose one of the options below to enable G29 Bed Leveling. The parameters
 * and behavior of G29 will change depending on your selection.
 *
 *  If using a Probe for Z Homing, enable Z_SAFE_HOMING also!
 *
 * - AUTO_BED_LEVELING_3POINT
 *   Probe 3 arbitrary points on the bed (that aren't collinear)
 *   You specify the XY coordinates of all 3 points.
 *   The result is a single tilted plane. Best for a flat bed.
 *
 * - AUTO_BED_LEVELING_LINEAR
 *   Probe several points in a grid.
 *   You specify the rectangle and the density of sample points.
 *   The result is a single tilted plane. Best for a flat bed.
 *
 * - AUTO_BED_LEVELING_BILINEAR
 *   Probe several points in a grid.
 *   You specify the rectangle and the density of sample points.
 *   The result is a mesh, best for large or uneven beds.
 *
 * - AUTO_BED_LEVELING_UBL (Unified Bed Leveling)
 *   A comprehensive bed leveling system combining the features and benefits
 *   of other systems. UBL also includes integrated Mesh Generation, Mesh
 *   Validation and Mesh Editing systems.
 *
 * - MESH_BED_LEVELING
 *   Probe a grid manually
 *   The result is a mesh, suitable for large or uneven beds. (See BILINEAR.)
 *   For machines without a probe, Mesh Bed Leveling provides a method to perform
 *   leveling in steps so you can manually adjust the Z height at each grid-point.
    With an LCD controller the process is guided step-by-step.
 */
//#define AUTO_BED_LEVELING_3POINT
//#define AUTO_BED_LEVELING_LINEAR
#define AUTO_BED_LEVELING_BILINEAR
//#define AUTO_BED_LEVELING_UBL
//#define MESH_BED_LEVELING

/**
 * Normally G28 leaves leveling disabled on completion. Enable
 * this option to have G28 restore the prior leveling state.
 */
//#define RESTORE_LEVELING_AFTER_G28

/**
 * Enable detailed logging of G28, G29, M48, etc.
 * Turn on with the command 'M111 S32'.
 * NOTE: Requires a lot of PROGMEM!
 */
//#define DEBUG_LEVELING_FEATURE

#if ENABLED(MESH_BED_LEVELING) || ENABLED(AUTO_BED_LEVELING_BILINEAR) || ENABLED(AUTO_BED_LEVELING_UBL)
  // Gradually reduce leveling correction until a set height is reached,
  // at which point movement will be level to the machine's XY plane.
  // The height can be set with M420 Z&lt;height&gt;
  #define ENABLE_LEVELING_FADE_HEIGHT

  // For Cartesian machines, instead of dividing moves on mesh boundaries,
  // split up moves into short segments like a Delta. This follows the
  // contours of the bed more closely than edge-to-edge straight moves.
  #define SEGMENT_LEVELED_MOVES
  #define LEVELED_SEGMENT_LENGTH 5.0 // (mm) Length of all segments (except the last one)

  /**
   * Enable the G26 Mesh Validation Pattern tool.
   */
  //#define G26_MESH_VALIDATION
  #if ENABLED(G26_MESH_VALIDATION)
    #define MESH_TEST_NOZZLE_SIZE    0.4  // (mm) Diameter of primary nozzle.
    #define MESH_TEST_LAYER_HEIGHT   0.2  // (mm) Default layer height for the G26 Mesh Validation Tool.
    #define MESH_TEST_HOTEND_TEMP  205.0  // (Â°C) Default nozzle temperature for the G26 Mesh Validation Tool.
    #define MESH_TEST_BED_TEMP      60.0  // (Â°C) Default bed temperature for the G26 Mesh Validation Tool.
  #endif

#endif

#if ENABLED(AUTO_BED_LEVELING_LINEAR) || ENABLED(AUTO_BED_LEVELING_BILINEAR)

  // Set the number of grid points per dimension.
  #define GRID_MAX_POINTS_X 3
  #define GRID_MAX_POINTS_Y GRID_MAX_POINTS_X

  // Set the boundaries for probing (where the probe can reach).
  //#define LEFT_PROBE_BED_POSITION MIN_PROBE_EDGE 10
  //#define RIGHT_PROBE_BED_POSITION (X_BED_SIZE - MIN_PROBE_EDGE) 167
  //#define FRONT_PROBE_BED_POSITION MIN_PROBE_EDGE 10
  //#define BACK_PROBE_BED_POSITION (Y_BED_SIZE - MIN_PROBE_EDGE) 202
  #define LEFT_PROBE_BED_POSITION 10
  #define RIGHT_PROBE_BED_POSITION 167
  #define FRONT_PROBE_BED_POSITION 10
  #define BACK_PROBE_BED_POSITION 206


  // Probe along the Y axis, advancing X after each column
  //#define PROBE_Y_FIRST

  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)

    // Beyond the probed grid, continue the implied tilt?
    // Default is to maintain the height of the nearest edge.
    //#define EXTRAPOLATE_BEYOND_GRID

    //
    // Experimental Subdivision of the grid by Catmull-Rom method.
    // Synthesizes intermediate points to produce a more detailed mesh.
    //
    //#define ABL_BILINEAR_SUBDIVISION
    #if ENABLED(ABL_BILINEAR_SUBDIVISION)
      // Number of subdivisions between probe points
      #define BILINEAR_SUBDIVISIONS 3
    #endif

  #endif

#elif ENABLED(AUTO_BED_LEVELING_UBL)

  //===========================================================================
  //========================= Unified Bed Leveling ============================
  //===========================================================================

  //#define MESH_EDIT_GFX_OVERLAY   // Display a graphics overlay while editing the mesh

  #define MESH_INSET 1              // Set Mesh bounds as an inset region of the bed
  #define GRID_MAX_POINTS_X 10      // Don't use more than 15 points per axis, implementation limited.
  #define GRID_MAX_POINTS_Y GRID_MAX_POINTS_X

  #define UBL_MESH_EDIT_MOVES_Z     // Sophisticated users prefer no movement of nozzle
  #define UBL_SAVE_ACTIVE_ON_M500   // Save the currently active mesh in the current slot on M500

  //#define UBL_Z_RAISE_WHEN_OFF_MESH 2.5 // When the nozzle is off the mesh, this value is used
                                          // as the Z-Height correction value.

#elif ENABLED(MESH_BED_LEVELING)

  //===========================================================================
  //=================================== Mesh ==================================
  //===========================================================================

  #define MESH_INSET 10          // Set Mesh bounds as an inset region of the bed
  #define GRID_MAX_POINTS_X 3    // Don't use more than 7 points per axis, implementation limited.
  #define GRID_MAX_POINTS_Y GRID_MAX_POINTS_X

  //#define MESH_G28_REST_ORIGIN // After homing all axes ('G28' or 'G28 XYZ') rest Z at Z_MIN_POS

#endif // BED_LEVELING

/**
 * Points to probe for all 3-point Leveling procedures.
 * Override if the automatically selected points are inadequate.
 */
#if ENABLED(AUTO_BED_LEVELING_3POINT) || ENABLED(AUTO_BED_LEVELING_UBL)
  #define PROBE_PT_1_X 20
  #define PROBE_PT_1_Y 160
  #define PROBE_PT_2_X 20
  #define PROBE_PT_2_Y 10
  #define PROBE_PT_3_X 180
  #define PROBE_PT_3_Y 10
#endif

/**
 * Add a bed leveling sub-menu for ABL or MBL.
 * Include a guided procedure if manual probing is enabled.
 */
//#define LCD_BED_LEVELING

#if ENABLED(LCD_BED_LEVELING)
  #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
  #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
#endif

// Add a menu item to move between bed corners for manual bed adjustment
//#define LEVEL_BED_CORNERS

#if ENABLED(LEVEL_BED_CORNERS)
  #define LEVEL_CORNERS_INSET 30    // (mm) An inset for corner leveling
  //#define LEVEL_CENTER_TOO        // Move to the center after the last corner
#endif

/**
 * Commands to execute at the end of G29 probing.
 * Useful to retract or move the Z probe out of the way.
 */
//#define Z_PROBE_END_SCRIPT &quot;G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10&quot;


// @section homing

// The center of the bed is at (X=0, Y=0)
//#define BED_CENTER_AT_0_0

// Manually set the home position. Leave these undefined for automatic settings.
// For DELTA this is the top-center of the Cartesian print volume.
//#define MANUAL_X_HOME_POS 0
//#define MANUAL_Y_HOME_POS 0
//#define MANUAL_Z_HOME_POS 0

// Use &quot;Z Safe Homing&quot; to avoid homing with a Z probe outside the bed area.
//
// With this feature enabled:
//
// - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
// - If stepper drivers time out, it will need X and Y homing again before Z homing.
// - Move the Z probe (or nozzle) to a defined XY point before Z Homing when homing all axes (G28).
// - Prevent Z homing when the Z probe is outside bed area.
//
#define Z_SAFE_HOMING

#if ENABLED(Z_SAFE_HOMING)
  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)     // X point for Z homing when homing all axes (G28).
  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)     // Y point for Z homing when homing all axes (G28).
#endif

// Homing speeds (mm/m)
#define HOMING_FEEDRATE_XY (100*60)
#define HOMING_FEEDRATE_Z  (4*60)

// @section calibrate

/**
 * Bed Skew Compensation
 *
 * This feature corrects for misalignment in the XYZ axes.
 *
 * Take the following steps to get the bed skew in the XY plane:
 *  1. Print a test square (e.g., https://www.thingiverse.com/thing:2563185)
 *  2. For XY_DIAG_AC measure the diagonal A to C
 *  3. For XY_DIAG_BD measure the diagonal B to D
 *  4. For XY_SIDE_AD measure the edge A to D
 *
 * Marlin automatically computes skew factors from these measurements.
 * Skew factors may also be computed and set manually:
 *
 *  - Compute AB     : SQRT(2*AC*AC+2*BD*BD-4*AD*AD)/2
 *  - XY_SKEW_FACTOR : TAN(PI/2-ACOS((AC*AC-AB*AB-AD*AD)/(2*AB*AD)))
 *
 * If desired, follow the same procedure for XZ and YZ.
 * Use these diagrams for reference:
 *
 *    Y                     Z                     Z
 *    ^     B-------C       ^     B-------C       ^     B-------C
 *    |    /       /        |    /       /        |    /       /
 *    |   /       /         |   /       /         |   /       /
 *    |  A-------D          |  A-------D          |  A-------D
 *    +--------------&gt;X     +--------------&gt;X     +--------------&gt;Y
 *     XY_SKEW_FACTOR        XZ_SKEW_FACTOR        YZ_SKEW_FACTOR
 */
//#define SKEW_CORRECTION

#if ENABLED(SKEW_CORRECTION)
  // Input all length measurements here:
  #define XY_DIAG_AC 282.8427124746
  #define XY_DIAG_BD 282.8427124746
  #define XY_SIDE_AD 200

  // Or, set the default skew factors directly here
  // to override the above measurements:
  #define XY_SKEW_FACTOR 0.0

  //#define SKEW_CORRECTION_FOR_Z
  #if ENABLED(SKEW_CORRECTION_FOR_Z)
    #define XZ_DIAG_AC 282.8427124746
    #define XZ_DIAG_BD 282.8427124746
    #define YZ_DIAG_AC 282.8427124746
    #define YZ_DIAG_BD 282.8427124746
    #define YZ_SIDE_AD 200
    #define XZ_SKEW_FACTOR 0.0
    #define YZ_SKEW_FACTOR 0.0
  #endif

  // Enable this option for M852 to set skew at runtime
  //#define SKEW_CORRECTION_GCODE
#endif
</code></pre>

CC BY-SA 4.0
2023-11-15T18:54:55.310Z
Since this is Marlin 1.1.9, please find some additional background information at [How to set Z-probe boundary limits in firmware when using automatic bed leveling?](https://3dprinting.stackexchange.com/q/8153/) on how the limits (used to) work in Marlin
0scar
<marlin><anet-a8><automatic-bed-leveling>
Anet A8 Auto Bed Levelling - Auto home not centring with new Marlin 1.1.9 config
Raynbow
# Anet A8 Auto Bed Levelling - Auto home not centring with new Marlin 1.1.9 config

(Asked by: username_0 on 2023-11-15)

Recently added a probe to my Anet A8 for auto bed levelling, calculations have been added based on position of probe to hotend as required. I'm using Marlin 1.1.9.
When I go into 'Prepare' in the printer settings to select auto home, it doesn't centre on the bed, seems to go to the back right. I presume this should be to the centre of the bed? I can't find where to change this in the config. Note the LCD screen shows X:153, Y:114. Config below.
//============================== Endstop Settings ===========================

// @section homing

// Specify here all the endstop connectors that are connected to any endstop or probe.
// Almost all printers will be using one per axis. Probes will use one or more of the
// extra connectors. Leave undefined any used for non-endstop and non-probe purposes.
#define USE_XMIN_PLUG
#define USE_YMIN_PLUG
#define USE_ZMIN_PLUG
//#define USE_XMAX_PLUG
//#define USE_YMAX_PLUG
//#define USE_ZMAX_PLUG

// Enable pullup for all endstops to prevent a floating state
#define ENDSTOPPULLUPS
#if DISABLED(ENDSTOPPULLUPS)
  // Disable ENDSTOPPULLUPS to set pullups individually
  //#define ENDSTOPPULLUP_XMAX
  //#define ENDSTOPPULLUP_YMAX
  //#define ENDSTOPPULLUP_ZMAX
  //#define ENDSTOPPULLUP_XMIN
  //#define ENDSTOPPULLUP_YMIN
  //#define ENDSTOPPULLUP_ZMIN
  //#define ENDSTOPPULLUP_ZMIN_PROBE
#endif

// Mechanical endstop with COM to ground and NC to Signal uses "false" here (most common setup).
#define X_MIN_ENDSTOP_INVERTING true  // set to true to invert the logic of the endstop.
#define Y_MIN_ENDSTOP_INVERTING true  // set to true to invert the logic of the endstop.
#define Z_MIN_ENDSTOP_INVERTING true  // set to true to invert the logic of the endstop.
#define X_MAX_ENDSTOP_INVERTING false // set to true to invert the logic of the endstop.
#define Y_MAX_ENDSTOP_INVERTING false // set to true to invert the logic of the endstop.
#define Z_MAX_ENDSTOP_INVERTING false // set to true to invert the logic of the endstop.
#define Z_MIN_PROBE_ENDSTOP_INVERTING true  // set to true to invert the logic of the probe.

// Enable this feature if all enabled endstop pins are interrupt-capable.
// This will remove the need to poll the interrupt pins, saving many CPU cycles.
//#define ENDSTOP_INTERRUPTS_FEATURE

/**
 * Endstop Noise Filter
 *
 * Enable this option if endstops falsely trigger due to noise.
 * NOTE: Enabling this feature means adds an error of +/-0.2mm, so homing
 * will end up at a slightly different position on each G28. This will also
 * reduce accuracy of some bed probes.
 * For mechanical switches, the better approach to reduce noise is to install
 * a 100 nanofarads ceramic capacitor in parallel with the switch, making it
 * essentially noise-proof without sacrificing accuracy.
 * This option also increases MCU load when endstops or the probe are enabled.
 * So this is not recommended. USE AT YOUR OWN RISK.
 * (This feature is not required for common micro-switches mounted on PCBs
 * based on the Makerbot design, since they already include the 100nF capacitor.)
 */
//#define ENDSTOP_NOISE_FILTER

//=============================================================================
//============================== Movement Settings ============================
//=============================================================================
// @section motion

/**
 * Default Settings
 *
 * These settings can be reset by M502
 *
 * Note that if EEPROM is enabled, saved values will override these.
 */

/**
 * With this option each E stepper can have its own factors for the
 * following movement settings. If fewer factors are given than the
 * total number of extruders, the last value applies to the rest.
 */
//#define DISTINCT_E_FACTORS

/**
 * Default Axis Steps Per Unit (steps/mm)
 * Override with M92
 *                                      X, Y, Z, E0 [, E1[, E2[, E3[, E4]]]]
 */
#define DEFAULT_AXIS_STEPS_PER_UNIT   { 100, 100, 400, 100 }

/**
 * Default Max Feed Rate (mm/s)
 * Override with M203
 *                                      X, Y, Z, E0 [, E1[, E2[, E3[, E4]]]]
 */
#define DEFAULT_MAX_FEEDRATE          { 400, 400, 8, 50 }

/**
 * Default Max Acceleration (change/s) change = mm/s
 * (Maximum start speed for accelerated moves)
 * Override with M201
 *                                      X, Y, Z, E0 [, E1[, E2[, E3[, E4]]]]
 */
#define DEFAULT_MAX_ACCELERATION      { 2000, 2000, 100, 10000 }

/**
 * Default Acceleration (change/s) change = mm/s
 * Override with M204
 *
 *   M204 P    Acceleration
 *   M204 R    Retract Acceleration
 *   M204 T    Travel Acceleration
 */
#define DEFAULT_ACCELERATION          400     // X, Y, Z and E acceleration for printing moves
#define DEFAULT_RETRACT_ACCELERATION  1000    // E acceleration for retracts
#define DEFAULT_TRAVEL_ACCELERATION   1000    // X, Y, Z acceleration for travel (non printing) moves

/**
 * Default Jerk (mm/s)
 * Override with M205 X Y Z E
 *
 * "Jerk" specifies the minimum speed change that requires acceleration.
 * When changing speed and direction, if the difference is less than the
 * value set here, it may happen instantaneously.
 */
#define DEFAULT_XJERK                 10.0
#define DEFAULT_YJERK                 10.0
#define DEFAULT_ZJERK                  0.3
#define DEFAULT_EJERK                  5.0

/**
 * S-Curve Acceleration
 *
 * This option eliminates vibration during printing by fitting a BÃ©zier
 * curve to move acceleration, producing much smoother direction changes.
 *
 * See https://github.com/synthetos/TinyG/wiki/Jerk-Controlled-Motion-Explained
 */
//#define S_CURVE_ACCELERATION

//===========================================================================
//============================= Z Probe Options =============================
//===========================================================================
// @section probes

//
// See http://marlinfw.org/docs/configuration/probes.html
//

/**
 * Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
 *
 * Enable this option for a probe connected to the Z Min endstop pin.
 */
#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN

/**
 * Z_MIN_PROBE_ENDSTOP
 *
 * Enable this option for a probe connected to any pin except Z-Min.
 * (By default Marlin assumes the Z-Max endstop pin.)
 * To use a custom Z Probe pin, set Z_MIN_PROBE_PIN below.
 *
 *  - The simplest option is to use a free endstop connector.
 *  - Use 5V for powered (usually inductive) sensors.
 *
 *  - RAMPS 1.3/1.4 boards may use the 5V, GND, and Aux4->D32 pin:
 *    - For simple switches connect...
 *      - normally-closed switches to GND and D32.
 *      - normally-open switches to 5V and D32.
 *
 * WARNING: Setting the wrong pin may have unexpected and potentially
 * disastrous consequences. Use with caution and do your homework.
 *
 */
//#define Z_MIN_PROBE_ENDSTOP

/**
 * Probe Type
 *
 * Allen Key Probes, Servo Probes, Z-Sled Probes, FIX_MOUNTED_PROBE, etc.
 * Activate one of these to use Auto Bed Leveling below.
 */

/**
 * The "Manual Probe" provides a means to do "Auto" Bed Leveling without a probe.
 * Use G29 repeatedly, adjusting the Z height at each point with movement commands
 * or (with LCD_BED_LEVELING) the LCD controller.
 */
//#define PROBE_MANUALLY
//#define MANUAL_PROBE_START_Z 0.2

/**
 * A Fix-Mounted Probe either doesn't deploy or needs manual deployment.
 *   (e.g., an inductive probe or a nozzle-based probe-switch.)
 */
#define FIX_MOUNTED_PROBE

/**
 * Z Servo Probe, such as an endstop switch on a rotating arm.
 */
//#define Z_PROBE_SERVO_NR 0   // Defaults to SERVO 0 connector.
//#define Z_SERVO_ANGLES {70,0}  // Z Servo Deploy and Stow angles

/**
 * The BLTouch probe uses a Hall effect sensor and emulates a servo.
 */
//#define BLTOUCH
#if ENABLED(BLTOUCH)
  //#define BLTOUCH_DELAY 375   // (ms) Enable and increase if needed
#endif

/**
 * Enable one or more of the following if probing seems unreliable.
 * Heaters and/or fans can be disabled during probing to minimize electrical
 * noise. A delay can also be added to allow noise and vibration to settle.
 * These options are most useful for the BLTouch probe, but may also improve
 * readings with inductive probes and piezo sensors.
 */
//#define PROBING_HEATERS_OFF       // Turn heaters off when probing
#if ENABLED(PROBING_HEATERS_OFF)
  //#define WAIT_FOR_BED_HEATER     // Wait for bed to heat back up between probes (to improve accuracy)
#endif
//#define PROBING_FANS_OFF          // Turn fans off when probing
//#define DELAY_BEFORE_PROBING 200  // (ms) To prevent vibrations from triggering piezo sensors

// A probe that is deployed and stowed with a solenoid pin (SOL1_PIN)
//#define SOLENOID_PROBE

// A sled-mounted probe like those designed by Charles Bell.
//#define Z_PROBE_SLED
//#define SLED_DOCKING_OFFSET 5  // The extra distance the X axis must travel to pickup the sled. 0 should be fine but you can push it further if you'd like.

//
// For Z_PROBE_ALLEN_KEY see the Delta example configurations.
//

/**
 *   Z Probe to nozzle (X,Y) offset, relative to (0, 0).
 *   X and Y offsets must be integers.
 *
 *   In the following example the X and Y offsets are both positive:
 *   #define X_PROBE_OFFSET_FROM_EXTRUDER 10
 *   #define Y_PROBE_OFFSET_FROM_EXTRUDER 10
 *
 *      +-- BACK ---+
 *      |           |
 *    L |    (+) P  | R <-- probe (20,20)
 *    E |           | I
 *    F | (-) N (+) | G <-- nozzle (10,10)
 *    T |           | H
 *      |    (-)    | T
 *      |           |
 *      O-- FRONT --+
 *    (0,0)
 */
#define X_PROBE_OFFSET_FROM_EXTRUDER -43
#define Y_PROBE_OFFSET_FROM_EXTRUDER -4
#define Z_PROBE_OFFSET_FROM_EXTRUDER 0
// X offset: -left  +right  [of the nozzle]
// Y offset: -front +behind [the nozzle]
// Z offset: -below +above  [the nozzle]

// Certain types of probes need to stay away from edges
#define MIN_PROBE_EDGE 10

// X and Y axis travel speed (mm/m) between probes
#define XY_PROBE_SPEED 6000

// Feedrate (mm/m) for the first approach when double-probing (MULTIPLE_PROBING == 2)
#define Z_PROBE_SPEED_FAST HOMING_FEEDRATE_Z

// Feedrate (mm/m) for the "accurate" probe of each point
#define Z_PROBE_SPEED_SLOW (Z_PROBE_SPEED_FAST / 2)

// The number of probes to perform at each point.
//   Set to 2 for a fast/slow probe, using the second probe result.
//   Set to 3 or more for slow probes, averaging the results.
#define MULTIPLE_PROBING 3

/**
 * Z probes require clearance when deploying, stowing, and moving between
 * probe points to avoid hitting the bed and other hardware.
 * Servo-mounted probes require extra space for the arm to rotate.
 * Inductive probes need space to keep from triggering early.
 *
 * Use these settings to specify the distance (mm) to raise the probe (or
 * lower the bed). The values set here apply over and above any (negative)
 * probe Z Offset set with Z_PROBE_OFFSET_FROM_EXTRUDER, M851, or the LCD.
 * Only integer values >= 1 are valid here.
 *
 * Example: `M851 Z-5` with a CLEARANCE of 4  =>  9mm from bed to nozzle.
 *     But: `M851 Z+1` with a CLEARANCE of 2  =>  2mm from bed to nozzle.
 */
#define Z_CLEARANCE_DEPLOY_PROBE   10 // Z Clearance for Deploy/Stow
#define Z_CLEARANCE_BETWEEN_PROBES  5 // Z Clearance between probe points
#define Z_CLEARANCE_MULTI_PROBE     5 // Z Clearance between multiple probes
//#define Z_AFTER_PROBING           5 // Z position after probing is done

#define Z_PROBE_LOW_POINT          -2 // Farthest distance below the trigger-point to go before stopping

// For M851 give a range for adjusting the Z probe offset
#define Z_PROBE_OFFSET_RANGE_MIN -20
#define Z_PROBE_OFFSET_RANGE_MAX 20

// Enable the M48 repeatability test to test probe accuracy
//#define Z_MIN_PROBE_REPEATABILITY_TEST

// For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
// :{ 0:'Low', 1:'High' }
#define X_ENABLE_ON 0
#define Y_ENABLE_ON 0
#define Z_ENABLE_ON 0
#define E_ENABLE_ON 0 // For all extruders

// Disables axis stepper immediately when it's not being used.
// WARNING: When motors turn off there is a chance of losing position accuracy!
#define DISABLE_X false
#define DISABLE_Y false
#define DISABLE_Z false
// Warn on display about possibly reduced accuracy
//#define DISABLE_REDUCED_ACCURACY_WARNING

// @section extruder

#define DISABLE_E false // For all extruders
#define DISABLE_INACTIVE_EXTRUDER true // Keep only the active extruder enabled.

// @section machine

// Invert the stepper direction. Change (or reverse the motor connector) if an axis goes the wrong way.
#define INVERT_X_DIR false
#define INVERT_Y_DIR false
#define INVERT_Z_DIR true

// @section extruder

// For direct drive extruder v9 set to true, for geared extruder set to false.
#define INVERT_E0_DIR false
#define INVERT_E1_DIR false
#define INVERT_E2_DIR false
#define INVERT_E3_DIR false
#define INVERT_E4_DIR false

// @section homing

//#define NO_MOTION_BEFORE_HOMING  // Inhibit movement until all axes have been homed

//#define UNKNOWN_Z_NO_RAISE // Don't raise Z (lower the bed) if Z is "unknown." For beds that fall when Z is powered off.

//#define Z_HOMING_HEIGHT 4  // (in mm) Minimal z height before homing (G28) for Z clearance above the bed, clamps, ...
                             // Be sure you have this distance over your Z_MAX_POS in case.

// Direction of endstops when homing; 1=MAX, -1=MIN
// :[-1,1]
#define X_HOME_DIR -1
#define Y_HOME_DIR -1
#define Z_HOME_DIR -1

// @section machine

// The size of the print bed
#define X_BED_SIZE 220
#define Y_BED_SIZE 220

// Travel limits (mm) after homing, corresponding to endstop positions.
#define X_MIN_POS -33
#define Y_MIN_POS -10
#define Z_MIN_POS 0
#define X_MAX_POS X_BED_SIZE
#define Y_MAX_POS Y_BED_SIZE
#define Z_MAX_POS 240

/**
 * Software Endstops
 *
 * - Prevent moves outside the set machine bounds.
 * - Individual axes can be disabled, if desired.
 * - X and Y only apply to Cartesian robots.
 * - Use 'M211' to set software endstops on/off or report current state
 */

// Min software endstops constrain movement within minimum coordinate bounds
#define MIN_SOFTWARE_ENDSTOPS
#if ENABLED(MIN_SOFTWARE_ENDSTOPS)
  #define MIN_SOFTWARE_ENDSTOP_X
  #define MIN_SOFTWARE_ENDSTOP_Y
  #define MIN_SOFTWARE_ENDSTOP_Z
#endif

// Max software endstops constrain movement within maximum coordinate bounds
#define MAX_SOFTWARE_ENDSTOPS
#if ENABLED(MAX_SOFTWARE_ENDSTOPS)
  #define MAX_SOFTWARE_ENDSTOP_X
  #define MAX_SOFTWARE_ENDSTOP_Y
  #define MAX_SOFTWARE_ENDSTOP_Z
#endif

#if ENABLED(MIN_SOFTWARE_ENDSTOPS) || ENABLED(MAX_SOFTWARE_ENDSTOPS)
  //#define SOFT_ENDSTOPS_MENU_ITEM  // Enable/Disable software endstops from the LCD
#endif

/**
 * Filament Runout Sensors
 * Mechanical or opto endstops are used to check for the presence of filament.
 *
 * RAMPS-based boards use SERVO3_PIN for the first runout sensor.
 * For other boards you may need to define FIL_RUNOUT_PIN, FIL_RUNOUT2_PIN, etc.
 * By default the firmware assumes HIGH=FILAMENT PRESENT.
 */
//#define FILAMENT_RUNOUT_SENSOR
#if ENABLED(FILAMENT_RUNOUT_SENSOR)
  #define NUM_RUNOUT_SENSORS   1     // Number of sensors, up to one per extruder. Define a FIL_RUNOUT#_PIN for each.
  #define FIL_RUNOUT_INVERTING false // set to true to invert the logic of the sensor.
  #define FIL_RUNOUT_PULLUP          // Use internal pullup for filament runout pins.
  #define FILAMENT_RUNOUT_SCRIPT "M600"
#endif

//===========================================================================
//=============================== Bed Leveling ==============================
//===========================================================================
// @section calibrate

/**
 * Choose one of the options below to enable G29 Bed Leveling. The parameters
 * and behavior of G29 will change depending on your selection.
 *
 *  If using a Probe for Z Homing, enable Z_SAFE_HOMING also!
 *
 * - AUTO_BED_LEVELING_3POINT
 *   Probe 3 arbitrary points on the bed (that aren't collinear)
 *   You specify the XY coordinates of all 3 points.
 *   The result is a single tilted plane. Best for a flat bed.
 *
 * - AUTO_BED_LEVELING_LINEAR
 *   Probe several points in a grid.
 *   You specify the rectangle and the density of sample points.
 *   The result is a single tilted plane. Best for a flat bed.
 *
 * - AUTO_BED_LEVELING_BILINEAR
 *   Probe several points in a grid.
 *   You specify the rectangle and the density of sample points.
 *   The result is a mesh, best for large or uneven beds.
 *
 * - AUTO_BED_LEVELING_UBL (Unified Bed Leveling)
 *   A comprehensive bed leveling system combining the features and benefits
 *   of other systems. UBL also includes integrated Mesh Generation, Mesh
 *   Validation and Mesh Editing systems.
 *
 * - MESH_BED_LEVELING
 *   Probe a grid manually
 *   The result is a mesh, suitable for large or uneven beds. (See BILINEAR.)
 *   For machines without a probe, Mesh Bed Leveling provides a method to perform
 *   leveling in steps so you can manually adjust the Z height at each grid-point.
    With an LCD controller the process is guided step-by-step.
 */
//#define AUTO_BED_LEVELING_3POINT
//#define AUTO_BED_LEVELING_LINEAR
#define AUTO_BED_LEVELING_BILINEAR
//#define AUTO_BED_LEVELING_UBL
//#define MESH_BED_LEVELING

/**
 * Normally G28 leaves leveling disabled on completion. Enable
 * this option to have G28 restore the prior leveling state.
 */
//#define RESTORE_LEVELING_AFTER_G28

/**
 * Enable detailed logging of G28, G29, M48, etc.
 * Turn on with the command 'M111 S32'.
 * NOTE: Requires a lot of PROGMEM!
 */
//#define DEBUG_LEVELING_FEATURE

#if ENABLED(MESH_BED_LEVELING) || ENABLED(AUTO_BED_LEVELING_BILINEAR) || ENABLED(AUTO_BED_LEVELING_UBL)
  // Gradually reduce leveling correction until a set height is reached,
  // at which point movement will be level to the machine's XY plane.
  // The height can be set with M420 Z
  #define ENABLE_LEVELING_FADE_HEIGHT

  // For Cartesian machines, instead of dividing moves on mesh boundaries,
  // split up moves into short segments like a Delta. This follows the
  // contours of the bed more closely than edge-to-edge straight moves.
  #define SEGMENT_LEVELED_MOVES
  #define LEVELED_SEGMENT_LENGTH 5.0 // (mm) Length of all segments (except the last one)

  /**
   * Enable the G26 Mesh Validation Pattern tool.
   */
  //#define G26_MESH_VALIDATION
  #if ENABLED(G26_MESH_VALIDATION)
    #define MESH_TEST_NOZZLE_SIZE    0.4  // (mm) Diameter of primary nozzle.
    #define MESH_TEST_LAYER_HEIGHT   0.2  // (mm) Default layer height for the G26 Mesh Validation Tool.
    #define MESH_TEST_HOTEND_TEMP  205.0  // (Â°C) Default nozzle temperature for the G26 Mesh Validation Tool.
    #define MESH_TEST_BED_TEMP      60.0  // (Â°C) Default bed temperature for the G26 Mesh Validation Tool.
  #endif

#endif

#if ENABLED(AUTO_BED_LEVELING_LINEAR) || ENABLED(AUTO_BED_LEVELING_BILINEAR)

  // Set the number of grid points per dimension.
  #define GRID_MAX_POINTS_X 3
  #define GRID_MAX_POINTS_Y GRID_MAX_POINTS_X

  // Set the boundaries for probing (where the probe can reach).
  //#define LEFT_PROBE_BED_POSITION MIN_PROBE_EDGE 10
  //#define RIGHT_PROBE_BED_POSITION (X_BED_SIZE - MIN_PROBE_EDGE) 167
  //#define FRONT_PROBE_BED_POSITION MIN_PROBE_EDGE 10
  //#define BACK_PROBE_BED_POSITION (Y_BED_SIZE - MIN_PROBE_EDGE) 202
  #define LEFT_PROBE_BED_POSITION 10
  #define RIGHT_PROBE_BED_POSITION 167
  #define FRONT_PROBE_BED_POSITION 10
  #define BACK_PROBE_BED_POSITION 206


  // Probe along the Y axis, advancing X after each column
  //#define PROBE_Y_FIRST

  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)

    // Beyond the probed grid, continue the implied tilt?
    // Default is to maintain the height of the nearest edge.
    //#define EXTRAPOLATE_BEYOND_GRID

    //
    // Experimental Subdivision of the grid by Catmull-Rom method.
    // Synthesizes intermediate points to produce a more detailed mesh.
    //
    //#define ABL_BILINEAR_SUBDIVISION
    #if ENABLED(ABL_BILINEAR_SUBDIVISION)
      // Number of subdivisions between probe points
      #define BILINEAR_SUBDIVISIONS 3
    #endif

  #endif

#elif ENABLED(AUTO_BED_LEVELING_UBL)

  //===========================================================================
  //========================= Unified Bed Leveling ============================
  //===========================================================================

  //#define MESH_EDIT_GFX_OVERLAY   // Display a graphics overlay while editing the mesh

  #define MESH_INSET 1              // Set Mesh bounds as an inset region of the bed
  #define GRID_MAX_POINTS_X 10      // Don't use more than 15 points per axis, implementation limited.
  #define GRID_MAX_POINTS_Y GRID_MAX_POINTS_X

  #define UBL_MESH_EDIT_MOVES_Z     // Sophisticated users prefer no movement of nozzle
  #define UBL_SAVE_ACTIVE_ON_M500   // Save the currently active mesh in the current slot on M500

  //#define UBL_Z_RAISE_WHEN_OFF_MESH 2.5 // When the nozzle is off the mesh, this value is used
                                          // as the Z-Height correction value.

#elif ENABLED(MESH_BED_LEVELING)

  //===========================================================================
  //=================================== Mesh ==================================
  //===========================================================================

  #define MESH_INSET 10          // Set Mesh bounds as an inset region of the bed
  #define GRID_MAX_POINTS_X 3    // Don't use more than 7 points per axis, implementation limited.
  #define GRID_MAX_POINTS_Y GRID_MAX_POINTS_X

  //#define MESH_G28_REST_ORIGIN // After homing all axes ('G28' or 'G28 XYZ') rest Z at Z_MIN_POS

#endif // BED_LEVELING

/**
 * Points to probe for all 3-point Leveling procedures.
 * Override if the automatically selected points are inadequate.
 */
#if ENABLED(AUTO_BED_LEVELING_3POINT) || ENABLED(AUTO_BED_LEVELING_UBL)
  #define PROBE_PT_1_X 20
  #define PROBE_PT_1_Y 160
  #define PROBE_PT_2_X 20
  #define PROBE_PT_2_Y 10
  #define PROBE_PT_3_X 180
  #define PROBE_PT_3_Y 10
#endif

/**
 * Add a bed leveling sub-menu for ABL or MBL.
 * Include a guided procedure if manual probing is enabled.
 */
//#define LCD_BED_LEVELING

#if ENABLED(LCD_BED_LEVELING)
  #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
  #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
#endif

// Add a menu item to move between bed corners for manual bed adjustment
//#define LEVEL_BED_CORNERS

#if ENABLED(LEVEL_BED_CORNERS)
  #define LEVEL_CORNERS_INSET 30    // (mm) An inset for corner leveling
  //#define LEVEL_CENTER_TOO        // Move to the center after the last corner
#endif

/**
 * Commands to execute at the end of G29 probing.
 * Useful to retract or move the Z probe out of the way.
 */
//#define Z_PROBE_END_SCRIPT "G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10"


// @section homing

// The center of the bed is at (X=0, Y=0)
//#define BED_CENTER_AT_0_0

// Manually set the home position. Leave these undefined for automatic settings.
// For DELTA this is the top-center of the Cartesian print volume.
//#define MANUAL_X_HOME_POS 0
//#define MANUAL_Y_HOME_POS 0
//#define MANUAL_Z_HOME_POS 0

// Use "Z Safe Homing" to avoid homing with a Z probe outside the bed area.
//
// With this feature enabled:
//
// - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
// - If stepper drivers time out, it will need X and Y homing again before Z homing.
// - Move the Z probe (or nozzle) to a defined XY point before Z Homing when homing all axes (G28).
// - Prevent Z homing when the Z probe is outside bed area.
//
#define Z_SAFE_HOMING

#if ENABLED(Z_SAFE_HOMING)
  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)     // X point for Z homing when homing all axes (G28).
  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)     // Y point for Z homing when homing all axes (G28).
#endif

// Homing speeds (mm/m)
#define HOMING_FEEDRATE_XY (100*60)
#define HOMING_FEEDRATE_Z  (4*60)

// @section calibrate

/**
 * Bed Skew Compensation
 *
 * This feature corrects for misalignment in the XYZ axes.
 *
 * Take the following steps to get the bed skew in the XY plane:
 *  1. Print a test square (e.g., https://www.thingiverse.com/thing:2563185)
 *  2. For XY_DIAG_AC measure the diagonal A to C
 *  3. For XY_DIAG_BD measure the diagonal B to D
 *  4. For XY_SIDE_AD measure the edge A to D
 *
 * Marlin automatically computes skew factors from these measurements.
 * Skew factors may also be computed and set manually:
 *
 *  - Compute AB     : SQRT(2*AC*AC+2*BD*BD-4*AD*AD)/2
 *  - XY_SKEW_FACTOR : TAN(PI/2-ACOS((AC*AC-AB*AB-AD*AD)/(2*AB*AD)))
 *
 * If desired, follow the same procedure for XZ and YZ.
 * Use these diagrams for reference:
 *
 *    Y                     Z                     Z
 *    ^     B-------C       ^     B-------C       ^     B-------C
 *    |    /       /        |    /       /        |    /       /
 *    |   /       /         |   /       /         |   /       /
 *    |  A-------D          |  A-------D          |  A-------D
 *    +-------------->X     +-------------->X     +-------------->Y
 *     XY_SKEW_FACTOR        XZ_SKEW_FACTOR        YZ_SKEW_FACTOR
 */
//#define SKEW_CORRECTION

#if ENABLED(SKEW_CORRECTION)
  // Input all length measurements here:
  #define XY_DIAG_AC 282.8427124746
  #define XY_DIAG_BD 282.8427124746
  #define XY_SIDE_AD 200

  // Or, set the default skew factors directly here
  // to override the above measurements:
  #define XY_SKEW_FACTOR 0.0

  //#define SKEW_CORRECTION_FOR_Z
  #if ENABLED(SKEW_CORRECTION_FOR_Z)
    #define XZ_DIAG_AC 282.8427124746
    #define XZ_DIAG_BD 282.8427124746
    #define YZ_DIAG_AC 282.8427124746
    #define YZ_DIAG_BD 282.8427124746
    #define YZ_SIDE_AD 200
    #define XZ_SKEW_FACTOR 0.0
    #define YZ_SKEW_FACTOR 0.0
  #endif

  // Enable this option for M852 to set skew at runtime
  //#define SKEW_CORRECTION_GCODE
#endif

**Tags:** marlin, anet-a8, automatic-bed-leveling
> **Comments:**
> **username_1**: Since this is Marlin 1.1.9, please find some additional background information at [How to set Z-probe boundary limits in firmware when using automatic bed leveling?](https://3dprinting.stackexchange.com/q/8153/) on how the limits (used to) work in Marlin  

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## 1 answers

### Answer by username_1 on 2023-11-15. Score: 0 | Accepted answer

Your config looks fine for the most of the definitions that have been compared to the known settings when using a probe.

You should be aware that with `#define Z_SAFE_HOMING` you define that the sensor is in the middle of the bed, however, the nozzle is then offset from the middle of the bed per the `#define X_PROBE_OFFSET_FROM_EXTRUDER -43` and `#define Y_PROBE_OFFSET_FROM_EXTRUDER -4` defined offsets.

So, when `G28` is commanded, the carriage will move to (110, 110) for the probe which is displayed as (110 - -43, 110 - -4) = (153, 114) for the nozzle.

So there is nothing wrong with the configuration, it works as it should.

> **Comments:**
> **username_0**: Thanks for that. I had the printer in storage for a few years and basically lost track of everything I'd learned previously. Good to know the config is correct. So basically the sensor is not expected to be dead sensor now, the starter Gcode will run it's setup and all is good?  
> **username_1**: @Raynbow You're welcome, but thanking is done through [accepting](https://3dprinting.stackexchange.com/help/someone-answers) and [upvoting (requires at least a 15 rep. though)](https://3dprinting.stackexchange.com/help/privileges/vote-up) answers. Please take the [tour] and read our [help] to find all about where Stack Exchange 3DPrinting is all about. We're all happy to help out! I once started with the Anet A8.  

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