HP2GBR reads Hewlett packard's plot file format (HPGL) and converts the plotter commands into Gerber photoplot code. The program is ideal for converting plot files generated on mechanical drafting programs into Gerber files for photoplotting. Designers who have been pen plotting PCBs and silkscreens will see a remarkable improvement in film quality when using a photoplotter.

HP2GBR is very fast and easy to use. Each pen is automatically mapped into a Gerber D-code. The user can optionally have all circle commands in HPGL converted into Gerber flashes. At the end of the conversion an aperture list in ASCII format is written to disk as well as Artwork's APT file so that the Gerber file can be easily imported into GBRVU.

Extra effort has been made to support plot files from various sources. Filters have been added to remove control characters encountered when copying files from tape or across computer platforms. Additional routines support dialects of HPGL that do not conform directly to the HPGL specification.

A scale factor has been incorporated so that 2X and 4X plot files can be reduced to plot 1:1 on photoplotters.

HP2GBR runs on 286 and higher PCs under DOS, Sun Sparc, Apollo Domain and HP 300/400 & 700 Series computers.

• Improve artwork quality by photoplotting instead of pen plotting.
• Ideal for PCBs and silk screens.
• Fast and easy to use.
• Robust parser handles various dialects of HPGL.
• Tested with plot files from many sources.
• Automatic pen to D-codes.
• Arcs to 360 degrees circular interpolation.
• Print out aperture list vs pen.
• Circles to flashes.
• Scale factor.

HPGL was developed by Hewlett Packard to drive its family of pen plotters. Most commands are vector oriented - pick up the pen, put down the pen, move here, move there. Very few complex commands are part of HPGL since the original plotters did not include powerful CPUs.

HPGL/2 was developed as a successor to HPGL to support many more advanced features that could be offloaded to plotters with powerful CPU's and large amounts of memory. HPGL/2 also includes quite a lot of raster controls and commands since most modern plotters are actually raster devices. This includes embedded pen definitions (up to 256 since a raster device can never run out of pens...) fill patterns, screened vectors, clipping windows, data transformation and the like.

Most plotter drivers do not take advantage of the advanced HPGL/2 functions since they are based on old code that originally supported basic HPGL. However one very popular HPGL/2 command that is often used is PE - poyline encoded command.

PE is very popular because it compresses the pen movement commands by encoding them. This significantly reduces the plot file size. However PE is more difficult to decode which is why many low cost (or no cost) HPGL to DXF programs don't properly support it. Needless to say, HP2DXF does support the PE command.

Command    HPGL   HPGL2    Description

SP          x      x       Selects a pen; data mapped to AutoCAD layer
                           layer no=10 x pen number + | line-type|

PA          x      x       move pen absolute

PR          x      x       move pen relative to current coordinates

PE                 x       polyline encoded - a series of movements encoded
                           to minimize bytes used.

PU          x      x       pen up

PD          x      x       pen down - any moves with pen down generate arcs, 
                           polyines

PW                 x       pen width - translated to polyline with width

IP          x      x       new user unit scale factor

AA          x      x       arc absolute

AR          x      x       arc relative

EA          x      x       outline of rectangle translated to a zero width
                           closed polyline

LB          x      x       string of text - to DXF text

DT          x      x       string termination character

SI          x      x       character height

DI          x      x       direction (angle) of text

CS          x      x       text scaling parameter

CI          x      x       circle

SC          x      x       scale factor

LT          x      x       line type - indirectly supported by mapping to a unique
                           AutoCAD layer.

DOS

SunOS

Solaris

HPUX