I have a US Cutter mh-721 MK-II and I recently bought a Prolific Technology, Inc. PL2303 Serial Port. Supposedly, I am supposed to be able to attach the cutter to the serial port, using the serial/usb adapter. I am also under the impression the serial adapter is supposed to show up as a printer, in Gnome/Ubuntu's printer detection program, but it doesn't I have tried telling inkscape to print directly to the /dev/ttyUSB0 port it creates, but that has no effect.

Does anyone have any advise?

Hi

Serial ports can be tricky, mix in USB and it get's worse!
See this; http://blog.mypapit.net/2008/05/how-to-use-usb-serial-port-converter-in-ubuntu.html

For faultfinding consentrate and sort out one piece at a time. Start with the computer side;

To get the handshake right try to wire a "null modem" cable which is wired in such a way as to provide its own handshaking.
See these:http://www.lammertbies.nl/comm/info/RS-232_flow_control.html
http://www.lammertbies.nl/comm/info/RS- ... .html#part
http://www.lammertbies.nl/comm/cable/RS-232.html

To test the USB serial on it's own you can use a loopback plug.
Once you are satisfied that the PC to USB/Serial is up and running you can connect the cutter and figure out the connection problem.

Here again concentrate on handshaking, you will also have to get the rest of the "equation" right - like;

Baud rate,
number of bits
number of stop bits,
flow control.

The PC and cutter side will have to use the same parameters (settings).

By testing this way a and keeping track of where you have been (take notes) you will get the connection to work.

Good Luck
RGDS
Ragnar

I figured out that I had to set permissions on /dev/ttyUSB0 to allow an unprivelaged user to access the device. Otherwise I'd have to run Inkscape as root.

chmod o+rw /dev/ttyUSB0

After that, it seems to be able to at least access the cutter. I'll let you know if it doesn't cut correctly. To be continued...