# Coordinates and axis count

The common Cartesian interface has six components, `[x, y, z, rx, ry, rz]`; the MG400 uses four, `[x, y, z, r]`. The mapping is `r = rz`. Since the MG400 cannot independently realize `rx` and `ry`, both must be zero for target positions. Returned values are expanded to `[x, y, z, 0, 0, r]`.

The common joint interface has six components, `[j1, j2, j3, j4, j5, j6]`; the MG400 has four axes. Returned values are expanded to `[j1, j2, j3, j4, 0, 0]`. Nonzero `j5` or `j6` targets cannot be executed.

Select work and tool coordinate systems using `change_work()` and `change_tool()`. Some work/tool definition read/write operations are unimplemented; consult the API reference.