[Beowulf] Re: multiport RS232 to ethernet (or USB)

Jim Lux James.P.Lux at jpl.nasa.gov
Thu Apr 6 15:50:34 PDT 2006


At 02:22 PM 4/6/2006, Ed Karns wrote:

>On Apr 6, 2006, at 12:00 PM, 
><mailto:beowulf-request at beowulf.org>beowulf-request at beowulf.org wrote:
>
>>
>>And, I suppose one could gang up a raft of $9 USB/Serial dongles on a USB 
>>hub (somehow, I suspect that this is fraught with peril)
>>
>>
>>The device has to allow independent control of RTS and reading CTS (which 
>>may not be used in the usual flow control scheme)
>
>
>It might be a tall order to get the ":cheap" $9 USB to Serial adapter to 
>do Request to Send / Clear to Send / hardware handshaking ... probably 
>should consider Xon / Xoff / software handshaking instead = not a problem 
>for the least expensive USB to Serial adapters. (Ctrl S / Ctrl Q being 
>easy from the command line or script to get the port to respond.)


Except that the piece of hardware the serial port is talking to uses RTS 
and CTS, not as handshaking lines, but to wake up the box, and to return 
status.

However, I did just try it with a cheap USB/RS232 adapter, and I can toggle 
RTS just fine from a program talking to a Windows COM port.  And, they 
"claim" that they have a Linux driver when I get to that step.  I'm sure 
it's the same FTDI USB/Serial chip that everyone uses.

Jim 
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