I just successfully accomplished exactly this process.
It's a multi-stage procedure and requires some 'tweaking' to get it to work
smoothly but the results are worth it.
1st off, you can't plot directly from Eagle. You have to generate HPGL files
I determined by experimentation it's best to run PADS and Traces separately
since I'm finding the file with everything combined is difficult to
troubleshoot, and you will have to troubleshoot it.
Once you have the files, use a GOOD text editor. I use TextPad which is
cheap and has an evaluation mode.
You have to edit the INIT string at the top of the file.
I am using a string I got from a plot to file output from my old ACAD v9
(DOS) of a PCB layout I did.
I tracked down a manual for the HP 7475A at www.sticker.tk
It explains the necessary commands.
the command string I use is
ESC .(; ESC.I81;;17;ESC.N;19;IN;SC;PU;PU;SP1;LT;VS36;
ESC.( ; "turn plotter on"
ESC.I81;;17; "Xoff level to 81" (Xoff when 81 characters left in buffer)
ESC.N:19: "sets intercharacter delay to 19" (not sure what units)
SC; "scaling = off"
PU; "Pen up"
SP1; "Select pen 1"
LT; "Line type solid"
VS36; "velocity 36" (pen speed)
ESC of course is not ascii ESC but the character 27 (TextPad allowsusing
such characters easily)
This string has to replace the string eagle generates from CAM.
it looks something like this (though the ESC gets mangled here)
.(; .I81;;17: .N;19:IN;SC;PU;PU;SP1;LT;VS36;
I have also found it necessary to break up the HPGL files into segments and
insert the INIT string at the head of each segment.
(I still working on figuring out what's going on here - I get plotter errors
The magic is in a program called Terminal V1.9b by Bray
I've uploaded a copy to one of my servers here:
it allows full control of COM parameters.
I am using a USB to Serial convertor (FTDI chip)
I have it configured as COM1
I set the parameters for 9600:N:8:1 XON-OFF
Terminal has a function to send a file.
Once you chop up the HPGL into pieces that won't choke it, you send each
piece to the COM port (the HP 7475A is connected to)
You also have to change the pen selection as eagle sets a different pen for
pads and traces . Edit the SP x in each file to SP1
Contact me if you want more info
"Thom" <email@example.com> wrote in message
Anyone had luck with EagleCad and an HP7475A? I'd like to use the 'ink
resist in the plotter' technique, but I'm not able to get Eagle to produce
anything that prints. I can get a test page printed on the system in
Win98 as well as a text file, but I don't understand how to get EagleCad