I've finally worked out a reasonable way to get plots of almost anything I would like on my HP 7475A serial plotter. After not playing with it for a long time for a variety of reasons, I decided to take another whack at it. Probably the most important thing to get right is the serial communication. With the dip switches on my plotter set to SWITCH  OFF  ON     LABEL PARITY  x          S2          x          S1 D        x          Y MET           x     US A4            x     A3               x     B4          x          B3 BAUD         x     B2          x          B1 This sets the plotter to 9600 baud, English (ANSI) B, "PC straight to Plotter" and no parity After you've checked your plotter, make sure the serial port is set up right. Probably the most important part of this is setting "crtscst". # stty 9600 parodd parenb ixon ixoff crtscst -F /dev/ttyUSB1 This is what my stty looks like afterwards. # stty -a -F /dev/ttyUSB1 speed 9600 baud; rows 0; columns 0; line = 0; intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = ; eol2 = ; swtch = ; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R; werase = ^W; lnext = ^V; flush = ^O; min = 1; time = 0; parenb parodd cs8 hupcl -cstopb cread clocal crtscts -ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr icrnl ixon ixoff -iuclc -ixany -imaxbel -iutf8 opost -olcuc -ocrnl onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0 isig icanon iexten echo echoe echok -echonl -noflsh -xcase -tostop -echoprt echoctl echoke At this point you should be able to just copy the HPGL file directly to the serial port assuming you have permissions to write to it. $ cat somefile.hpgl > /dev/ttyUSB1 The error light on the plotter will flash on a sort of regular interval. I don't know if that means it still has data in the buffer or if it's just an indication of data transfer. I've only had problems with one or two plots. --------- The second part of this is how to get almost any line drawing to the plotter. Almost all unix-y applications can output postscript. Print your drawing to a postscript file. The next piece may be tricky to find, but it's called ps2hpgl. It consists of a ps2hpgl.ps file and uses ghostscript to convert the postscript to HPGL. I understand Inkscape can create HPGL files directly, but I have yet to get them to work right. I've created a package that installs ps2hpgl.ps in the right library directory of ghostscript and a script that is basically a ripoff of ps2ascii so I can run it anywhere. The next thing you need is "hpglview". This is available from CERN at http://service-hpglview.web.cern.ch/service-hpglview/ Read the README, it has a snippet of code to create a shell script to run it from anywhere. I found ps2hpgl creates upside down plots (not that matters much) but it creates HPGL files that are not consistently sized (or rather consistently undersized). hpglview allows me to resize the plot to whatever size I want as well as rotate it. That's about it in a nutshell. Good luck.