usb serial programming

[amadeus84@verizon.net (Amadeus W.M.)]

On Mon, 21 Jul 2014 11:18:28 -0700, Greg KH wrote:

> On Mon, Jul 21, 2014 at 03:19:00AM +0000, Amadeus W.M. wrote:
>> Not sure if this is the right venue for this question, please direct me to
>> the right place if it's not.
>> 
>> I have a C program that opens the serial port /dev/ttyS0 and sends commands 
>> (as strings) back and forth to a pan-tilt-zoom camera. That works very well,
>> but I want to use the camera with a Raspberry Pi, which of course does not 
>> have a serial port (RS232). One option is to use a RS232 to usb adapter and 
>> rewrite the C code for the usb port. So how do I go about that? Is
>> usb serial port programming possible and documented anywhere? 
> 
> Nothing to "rewrite", just point your code at /dev/ttyUSB0 instead, and
> away you go...

Thanks for the prompt answer!

That's what I was hoping for, and I would have tried that, but I don't
have any /dev/ttyUSBX. I am connecting the camera to a usb to RS232 
cable:

http://www.amazon.com/gp/product/B000BI95W0/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

Does this mean my adapter is not supported by linux? Also, nothing 
happens in /var/log/messages when I plug the cable into the usb port. 
This is my lsusb:

1) root:~> lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 005 Device 003: ID 0c45:1050 Microdia CF Card Reader
Bus 005 Device 002: ID 046d:c016 Logitech, Inc. Optical Wheel Mouse
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 008: ID 0764:0501 Cyber Power System, Inc. CP1500 AVR UPS
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 005: ID 04fc:0561 Sunplus Technology Co., Ltd Flexcam 100
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

No trace of the adapter.


Should /dev/ttyUSB0 pop up when I plug the adapter into the usb port,
even before I connect anything to the serial port of the cable? 

If the adapter is not supported, can I write a driver for it? I'll be happy to,
with a little guidance to get me started. Any pointers?

Thanks!