The Plotter Coordinate System

The plotting surface of all HP plotters is a Cartesian coordinate system that is scaled in plotter units. The plotter unit is the smallest possible addressable move and is 0.025 mm (approximately 0.001 in.) in length. The orientation of the X- and Y-axes, the locations of the origin point, and the default location of scaling points P1 and P2 are shown in the following diagrams. The paper is shown as thugh you were facing the front of the plotter and looking down on it. Default coordinate values for P1 and P2 and the plotter-unit range within the mechanical (hard-clip) limits of each plotter are included in the table entitled Plotting Areas and Default P1, P2 Locations.

Dick Bentley [bentley at northnet.org] says:

...the diagrams shows a rectangle representing the paper with origin (0,0) shown at lower left with +Y going up, and +X going right. The origin (0,0) is the exact corner of the paper. Inside this rectangle is a dotted line rectangle labeled 'Soft-Clip limits', and the edge of the paper itself (the outside rectangle) is labeled 'Hard-Clip limits'. Inside the Soft-Clip limits (the dotted line rectangle) is shown P1 (down near the lower left and inside the dotted rectangle) and P2 (at upper right and inside the dotted rectangle).

The plotter unit is 0.025 mm (0.0009842 inches - to be exact) and is apparently equal in both X and Y.

And... I will now make another guess that the values of P1 and P2 as set by default or by an IP command mean absolutely nothing unless an SC is also given in which case P1 and P2 will affect both the scaling of user units AND offset in both X and Y.

If you have any comments either agreeing or disagreeing with any or all of the above, please have at it.

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