[Wlug] Multiple RS232 Com Ports...
Stephen C. Daukas
scd at daukas.com
Sun May 20 12:19:54 EDT 2007
I'm wondering if anyone knows how many RS232 devices a "vanilla" Linux
kernel can manage simultaneously. I'd like to be able to have up to 32
going at once, with data taken from each device written to its own file
via the standard I/O subsystem. As far as I know, wouldn't Linux simply
fork the appropriate number of driver threads to read as many RS232
ports as are attached with each device's stream written to a "/dev" file?
Why do I want to do this? Glad you asked...
I'm investigating an issue at work that involves our instrumentation lab
having to upload/download/calibrate multiple sondes and have them ready
for field deployment the next day. Currently, we can do three at a time
and this takes about 8-9 hours providing everything goes well.
The manufacturer's software application claims to supports the
simultaneous upload/config of up to 32 sondes. The application will
scan "installed" COM ports looking for recognizable sondes, and present
those found to the user. Yes - this is a windows solution, so I first
began looking for products that would play with Windows...
I began looking for hardware solutions (PCI boards, break-out boxes,
etc.) on the net and I found a few that will provide 16 DB-9 RS232 ports
with full pin-out support as well as so-called "true" interrupt and FIFO
support on the host (via their own custom Windows driver, no doubt).
And then I started wondering about how to get all of this to work in a
Windows environment where "IT" is the only group allowed to install
software and otherwise configure a PC for most users whose biggest
concern is email...
All this got me thinking about avoiding the whole Windows issue and
instead thinking about using Linux to take care of the RS232 part, with
the newly created files moved to a Windows box (sneakernet to start
with), with the normal post-processing of the data taking place as usual
in the Windows environment the staff is used to...
I'm hoping an "out of the box" distro will be able to handle say 16
RS232 ports and that Linux-based terminal emulation software is
available to simultaneously handle those ports as well so I can capture
the data using the appropriate protocols... Anyone know of a similar
application using RS232 and Linux, or have some thoughts on this?
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