On 5/21/07, Karl Hiramoto <karl@hiramoto.org> wrote:
Mike Frysinger wrote:
On 5/20/07, Stephen C. Daukas <scd@daukas.com> wrote:
I'm wondering if anyone knows how many RS232 devices a "vanilla" Linux kernel can manage simultaneously.
there shouldnt be any real limit ... at work, we have ~24 USB<->RS232 devices hooked up and we use them all simultaneously to interact with some hardware
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?
i'd be more worried about *what* the devices are and *how* you connect your 32 devices to the machine ... making sure linux has proper device driver support for it -mike
The *how* is the heart of my question... If you mean how physically, that's a matter of cable and such. The driver question is, again, what I was looking into. If Linux has support for multiple RS232s built in to one or more generic drivers in a given distro, then we are talking about terminal emulation - a.k.a. VT100 or ANSI or whatever. Currently, the lab uses hyperterminal to talk with the sondes - the sondes are intelligent and provide a tty-based menu for command and control. The devices are known, so the *what* isn't really an open question.
Yes, there should be no real limit.. At work i have use multile Edgeport/8 http://www.digi.com/products/usb/edgeport.jsp devices to have may rs-232 ports
How do the RS232 FIFO/Interrupts get managed via USB? In other words, each of the RS232s will need to have its "pin-outs" (DB-9) active so the sondes believe they are connected in order to avoid their "turning off". Also, is it safe to assume the edgeport has its own drivers? Regards, Steve