the TX line is always at between -3 and -12 volts...
If it's pin 2 then it's a DTE if it's pin 3 its a DCE
if it's a DTE you need a crossover if it's a DCE you don't... assuming all the
other pins are wired accordingly..
On 22-Nov-99 Kenn Humborg wrote:
> On Mon, Nov 22, 1999 at 02:23:17AM -0000, subb3 at ibm.net wrote:
>>>> I am trying to connect to a Cisco router via console. The
>> router and the linux box are connected via a serial cable.
>> I have seyon but have never used it. What device name is the serial port on?
>> I need to access this router and any help is appreciated.
>> You're working late!
>> The serial port is /dev/ttyS0 to /dev/ttyS3 (for DOS's COM1: to COM4:).
> On a 2.0.x kernel you might need to use /dev/cua0 to /dev/cua3 instead.
>> Your cable probably needs to be a crossover (aka null-modem) cable.
> A cable that you'd use to connect a PC to a modem is _not_ a crossover.
>> In a 25-way to 25-way (or 9-way to 9-way) crossover, pins 2 and 3 are
> crossed over. In a 25-way to 9-way crossover, pins 2 and 3 are connected
> straight through. A quick test with a multimeter will identify the
> cable if there is any doubt.
> Irish Linux Users' Group: ilug at linux.ie>http://www.linux.ie/mailman/listinfo/ilug for (un)subscription information.
> List maintainer: listmaster at linux.ie
John Ronan <j0n at tssg.wit.ie>, +353-51-302411
Telecommunications Software Systems Group - WIT, http://www.tssg.wit.ie
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