# M557

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#### M557: Set Z probe point or define probing grid

**Parameters to define G29 probe grid (all values in mm)**

**Xaaa:bbb**Minimum and maximum X coordinates to probe**Yaaa:bbb**Minimum and maximum Y coordinates to probe**X,Y,U,V,W,A,B,C...aaa:bbb**Minimum and maximum coordinates of an arbitrary axis (except Z) to probe (RRF >=3.3beta2)**Raaa**Radius to probe**Saaa**Probe point spacing (RepRapFirmware 1.19beta10 and later also support**Saaa:bbb**)**Pnn**or**Pxx:yy**(RRF 2.02 and later) Number of points to probe in the X and Y axis directions (alternative to specifying the probe point spacing)

**Examples**

- M557 X0:200 Y0:220 S20
- M557 X0:100 Y0:120 S50:60
- M557 R150 S15

In RRF >= 3.3beta2 it is possible to use an arbitrary axes pair for probing, e.g. X-A or U-C. When using **Raaa** to define a radius this will default to X-Y.

**Parameters to define G32 probe points (Cartesian/CoreXY printers only, deprecated and not supported in firmware 1.18 and later)**

**Pnnn**Probe point number**Xnnn**X coordinate**Ynnn**Y coordinate

**Example**

- M557 P1 X30 Y40.5

Set the points at which the bed will be probed to compensate for its plane being slightly out of horizontal.

The first form defines the grid for G29 bed probing. For Cartesian printers, specify minimum and maximum X and Y values to probe and the probing interval. For Delta printers, specify the probing radius. If you define both, the probing area will be the intersection of the rectangular area and the circle. There is a firmware-dependent maximum number of probe points supported. Currently this is 121 on the Duet 06/085 (enough for a 11x11 grid) and 441 for the Duet 2 WiFi and Duet 2 Ethernet (enough for a 21x21 grid)

The second form defines the points for for G32 bed probing. The P value is the index of the point (indices start at 0) and the X and Y values are the position to move extruder 0 to to probe the bed. An implementation should allow a minimum of three points (P0, P1 and P2). This just records the point coordinates; it does not actually do the probing. See G32. Defining the probe points in this way is deprecated in RepRapFirmware, you should define them in a bed.g file instead.

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