Gene,
I tried a pl2303 serial to USB one and had problems. It was a radio shack branded device.
Using FC4 at the time it looked like only every other character was being received by the host. Data to the device was fine. Unfortunately, I never resolved the problem and opted for a four port Keyspan device. No problems connecting through it to the same serial device.
If the Garmin only has four wires, most likely the handshake is XON/XOFF, if any. Does the Garmin "talk" correctly via one of the "real" serial ports?
Bob...
Gene Heskett wrote:
Greetings;
Trying to get roadnav to talk to my elderly Garmin 12, and because I'm out of serial ports, the garmin 4 pin to db9 connector cable is plugged into the db9 end of a pl2303 serial to usb adaptor. The pl2303 is recognized and assigned to /dev/ttyUSB0 according to dmesg.
I'm apparently getting zero data from the garmin and I suspect its the lack at least the 7 wire protocol at the garmin side of the pl2303. I believe it may even be just a 2 wire & ground setup as the garmin connector is only a round 4 pin, probably with little or no flow control as the garmin apparently runs at 4800 baud only.
But, I'd like to ask here on this list: Has anyone ever made a pl2303 based adaptor actually work?
The only other time I seriously tried to use this $40 gizmo was as an interface translator with the rs-232 pack of a vintage coco on the other end. At that time I was able to type back and forth using terminal programs on both, but a known good zmodem setup on the coco failed to move more than about 10 bytes of a 10k file when I had minicom attempt the transfer. At the time I also suspected config/handshake problems and eventually gave up, but now I think the pl2303 may be busted or miss-configured, hence the request for a gui program to monitor individual wire status at the db9 connector, but do it using /dev/ttyUSB(x).
Is this latter idea even possible?
Thanks everybody.