RS232 over Ethernet

(Cisco serial console, RJ45 konzole)

http://www.cisco.com/c/en/us/support/docs/routers/7000-series-routers/12223-14.html

http://www.instructables.com/id/Simple-RJ45-DB9-Cisco-console-cable/

http://www.cyberflunk.com/~nikm/cisco/cisco-de9/

RJ45	CAT5 Color	DE9	RS232	DE9 Color
1	orange-white	8	CTS	Clear to send	Blue
2	orange	6	DSR	Data set ready	Orange
3	green-white	2	RXD	RX	Black
4	blue	5	GND	Signal GND	Red (not yet! - see below)
5	blue-white	5	GND	Signal GND	Green (not yet! - see below)
6	green	3	TXD	TX	Yellow
7	brown-white	4	DTR	Data terminal ready	Brown
8	brown	7	RTS	Request to send	White (or Grey)

DB9 - RJ45 redukce

RJ45	CAT5 Color	DE9	RS232
1	orange-white	7	RTS	Request to send
2	orange	4	DTR	Data terminal ready
3	green-white	3	TXD	TX
4	blue	5	GND	Signal ground
5	blue-white	9	RI	Ring Indicator
6	green	2	RXD	RX
7	brown-white	6	DSR	Data set ready
8	brown	8	CTS	Clear to send

(měřeno na zapojeném UTP kabelu)

Rollover kabel

Je potřeba prohodit DB9 piny 2 a 3, na to se používá tzv. rollover kabel, kterej má všechny piny v rj45 zapojený na jedný straně opačně než na druhý…

Null modemy

Null modem je kabel s db9 konektory na obou stranách, s překříženým rx/tx, který nám umožňuje komunikaci mezi dvěmi zařízeními. Zapojení takového kabelu je zde.

http://www.lammertbies.nl/comm/cable/RS-232.html

Dumb

Loopback handshake

CD Audio Null Modem

Take some old unused analog audio cable from CD drive and swap red and black wires on one side (the two wires closer to each other). Such cable then can be used as null modem when you push it on pins 2,3 and 5 of RS232 DB9 connector. (pin 4 will go to empty position of connector).

Voila! You have smallest and cheapest null modem.