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VUTRAX Technical SupportVUTRAX SOFTWARE ADVICE NOTICE 96 - 13 Feb 1992 PLOTTING TO HPGL PLOTTERS - SPEEDING UP PAD DRAWING Output of PCB layouts to pen-plotters can be very time consuming owing to the number of operations necessary to fill areas. The worst of these is normally the drawing of filled circles for component pads, vias, and end-rounding (option Q1). The following suggests ways in which to improve such plotting. A guide to each likely performance improvement is listed in brackets. For those items suggesting changes to the .PXY file, first COPY \VUTRAX\MAIN\HPGL<whatever>.PXY \VUTRAX\MAIN\TRIAL.PXY and apply changes to \VUTRAX\MAIN\TRIAL.PXY. For testing, use the [SELECTPLOTTER] menu box to select plot control file TRIAL.PXY o For check plots use option Q2 to obtain outline only. Since this prevents all filling, use of other items with this scheme either have no effect, or in the case of forcing white space, are counterproductive. (600% faster) o Ensure that you are using the largest available pen for the job. An additional large pen in the colour appropriate to the pads, will be selected in preference to a smaller one when possible, and can greatly reduce the number of drawing strokes. Simply add any additional available pens to the appropriate .NIB file. e.g. Draw 12 12 +02 -02 A Fixed '0.12" BLK FIBRE' '1' Draw 24 24 +02 -02 A Fixed '0.24" BLK FIBRE' '2' with the wider pen in position 2. (100% upwards). o Minimise the overlap between passes by altering the .PXY as described in the introduction. Find line $SN=4;$N Minimum overlap on constructions and change 4 to the smallest value that fills without leaving white streaks between lines. If you can set this to 0 and still get no white streaks then the pen is probably drawing a wider line than you have tabulated in the .NIB file. (20% faster) o Apply the Force Whitespace option Q36 which reduces the amount of fill required (30% faster). o If the actual drawing of circles is substantially slower than similar length line drawing operations try either of the following (but not both together):- * Alter line $SN=4;$N Node fill using concentric ... to $SN=0;$N Node fill using Octagons (50% faster) * In line $T4=$... ...C;,10;$K10;$R$U$ Change the 10 in ,10; (not $K10) to 20, 30 or 45 to change the cord angle from 10 to the nominated number of degrees. 45 produces octagons maybe faster, maybe not, than line drawing them as the first item. (40% faster) |