Re: HP Plotter print process

Ok

Finally spent enough time to figure out just what was happening.

You can ignore pretty much most of the previous posting, since it was a knee

jerk reaction to constant errors I was getting.

I am using a Chinese USB to serial converter based on the FTDI chip.

Running unders Windoze XP, the timing of software signals is somewhat "soft"

as far as USB goes.

I was trying to use X-on X-off handshaking because that's what ACAD V9 does

and that's all I had to compare with.

Once I changed the setting in Bray's Terminal V1.9 to RTS/CTS everything

fell into place.

Apart from editting the HPGL file for Pen selection and a "push the page out

for viewing at the end. it is now possible to use the HPGL file straight

from Eagle's CAM module.

For some reason, the Arc Absolute eagle uses to draw large pads really

screws up the X-on X-off timing. If I isolated those lines, I could get the

plot to run and if I fed them one at a time to the COM port thay worked but

as a script no-go.

Hope this helps anyone looking to plot to a HP 7475A pen plotter directly to

copper.

I still plan to create a webpage detailing the process for us hobbyists.

Don Soucy

"Don Soucy" <editor@primegood.com> wrote in message

news:h2kakm$c1u$1@cheetah.cadsoft.de...

Hi Thom

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 using CAM.

 

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)

IN;                  "Initialize"

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 otherwise)

 

The magic is in a program called Terminal V1.9b by Bray

I've uploaded a copy to one of my servers here:

 

http://www.primegood.com/docs/termv19b.zip

 

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

editor@primegood.com

 

Good Luck

Don Soucy

 

 

 

 

 

"Thom" <tkreider1@cox.net> wrote in message

news:fib2ua$srh$1@cheetah.cadsoft.de...

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 to plot...

 

Thoughts?