Software Companions delivers three different plot file viewers: ViewCompanion Standard, Pro and Premium.
All of them can view, print and convert HPGL, HPGL-2, HP-RTL and Calcomp formatted plotter files (PLT).
Using ViewCompanion you can:
The Pro and Premium editions add a markup feature, and support for additional file formats.
Please read the different product descriptions for more information:
Read more about ViewCompanion Standard
Read more about ViewCompanion Pro
Read more about ViewCompanion Premium
You can find a ViewCompanion family comparison chart, that list the main differences between the editions, here:
ViewCompanion Family Comparison Chart
A fully functional evaluation copy can be downloaded from our web site. The downloaded product will run in evaluation mode
for a period of 30 days. After the trial period you're required to purchase a license, if you want to continue to use the product.
ScConverter may be what you're looking for; it can easily be integrated using either COM, or ordinary DLL import.
scConverter can convert PLT, CGM, DWF, TIFF, Gerber and other formats, to an extensive list of output formats which includes PDF, DXF, TIFF, PNG, JPG and DWF.
A complete list of input and output formats can be found on the product homepage: