DSR/DTR hardware flow control for usb/RS232 serial

Hi all,

I'm currently trying to use an old HP pen plotter to make art. So far, I've been able to send simple HP-GL instructions to the plotter using a usb-serial FTDI cable and the chiplotle library. Everything works there -- yay!

One thing I haven't been able to make use of is DSR/DTR hardware flow control. As far as I can tell, this has never been implemented in the usbserial module. Does anyone know of a software workaround for this? (I would like to avoid rewiring the cable to use RTS/CTS pins.) Does anyone know of a patch to the driver that implements DSR/DTR?

Thanks for any help!


This may or may not be a resolution, did a search on DDG

Thanks for the link. I may be mistaken, but it seems like the kernel patch only provides the functions to address the DSR/DTR pins. Does that mean I would have to write my own driver? I don't really feel qualified to do that properly.


I'm not experienced in this issue, I just gave you a link to see if it will provide further solutions. However if you do a search for your issue on DDG, there is a great number of links that may help.