Difference between PLT and HPGL



Can someone explain me what is different between .PLT and .HPGL?


HPGL, less often referred in full as HP Graphics Language Plotter file, is a file format that contains a few lines of setup commands, followed by a list of printing commands, which tell the plotter what and where to draw on the page. Usually, HPGL is used to send information to plotter printers.

PLT, in its turn, is an AutoCAD Plotter Document. Based on HPGL, this format is used for vector-based plotter files created by AutoCAD drawing software. PLT files can be printed using a plotter, which prints images using lines instead of dots.


MOST of the time .plt files will contain HPGL commands because most AutoCad users have HP plotters or HP-compatible plotters.

The PLT file can have any type of print file inside it (HPGL/HPRTL/HPGL2/ECM/PostScript/etc.), it is a ‘wrapper’ around another file. The ‘.plt’ extension keeps things simple for AutoCad users.

AutoCad expects the user to select a plotter, then creates the printable file using the plotter’s driver and adds the .plt extension. In Valentina, when the .plt option is implemented, you will be prompted to select your printer/plotter or filetype to put inside the .plt file.



Thanks Susan. This is exactly what i need.

This is little bit not what i expected. I don’t know how to use plotter’s driver. And seem like QPrinter class doesn’t know how to work with plotters too.

For example i looked on Inkscape. It can generate a HPGL file and a PLT file. When you generate a HPGL file Inkscape asks additional questions. And the file contains information for plotter. But if select PLT file no additional information asked, and for me seem like the file contains only an image.

I can make the second case too. Natively, without any plotter’s driver, generate HPGL instructions. But will it be useful? Maybe only if user could use any additional program. For example Inkscape with plugin Inkcut.

If what you want is something like plugin Inkcut this is additional task and far more complex. Right now i don’t see any possibility to send data to plotter by Valentina.


The .plt file’s usefulness may be solely in file management - all AutoCad plot files have the same extension. There doesn’t seem to be any other benefit - no other programs import .plt files. Perhaps we shouldn’t spend time on an export option that doesn’t provide value.


Inkscape opens such files.


Okay, I looked at Inkscape. File Import: Interesting that Inkscape will open lots of print file formats if they contain vector commands (like Postscript). http://wiki.inkscape.org/wiki/index.php/Frequently_asked_questions#What_formats_can_Inkscape_import.2Fexport.3F

File Export: Inkscape allows Save As to:

  1. .PLT, but it makes the choice for the user to use HPGL inside the .PLT file. No other .PLT choices are available.
  2. .HPGL, without encapsulation within a .PLT wrapper. Exporting directly to .HPGL gives ability to send the file to an HP plotter with native plotter code so no need to go through a printer driver. This results in super speedy printing. Plutting HPGL code within .PLT wrapper adds nothing to this process.

Question: PDF and SVG are the top two file interchange formats to share vector-based images between programs. .PLT is not used by much more than AutoCad and Inkscape (bless their overachieving NP-complete little hearts :smiley: Should we raise the priority of .PLT file export ahead of other more necessary improvements?


I actually see a need for .PLT import once ‘Reverse Engineering’ is implemented, but no pressing use case for exporting. I vote for waiting on this, unless someone wants to volunteer to specifically do this.


Thomas HOCEDEZ created an issue 2016-10-03 Hello, I’m converting PDF/DXF outputs of Valentina into Inkscape to use my plotter. This is quite boring as there can be loss of precision or scale. It would be nice that the printed output of Valentina could be send to a plotter. i think It would be possible convert & send HPGL through serial port, using the code of inkcut or the HPGL output of Inkscape. Thnaks.


@thomas.hocedez doesn’t require .PLT only .HPGL (actually this is now HP-GL/2 code with .hpgl extension because HP doesn’t support HP-GL code anymore). Most modern plotters can receive PostScript (.PS) files. Layouts can be exported to .PS with File/Layout/Export As/Postscript option. Many modern plotters also accept PDF and SVG.if their driver includes these features, as mine does, it is an Epson SureColor 7000. Layouts can be exported to .PDF and .SVG under the Layout options too.


For someone preparing to purchase a plotter for the first time, is there any brand or model that will be best for printing from Valentina? Thank you.


This day came!:smile:


This day came!:smile:

Many modern plotters also accept PDF and SVG.if their driver includes these features, as mine does, it is an Epson SureColor 7000.

Thanks, @dismine. Are you saying additional compatibility will be supported in the future? I should have read @slpencer’s last post more carefully. I think the existing file export features are adequate for me. I will look for this model, or one with an equivalent driver.

Is there anything to be gained from printing any of the file format’s other than PDF? I have limited experience with digital patterns and markers but it seems to me that a PDF should be perfectly fine in all situations.


No. I am saying that someone asking question that i have been expecting. It is similar to “Does this printer will work on Linux”? Not opposite. This mean we begin creating influence on plotters users what to buy. Little bit selfish, i know.:wink:


No. I am saying that someone asking question that i have been expecting.

Oh, I see! Awesome! In that case I am pleased to have asked. Yes, Valentina officially holds power in the marketplace! :smile: