Hi,
From
http://www.cisco.com/univercd/cc/td/doc/product/software/ssr83/tsc_r/54008.htm
Generating a Hardware Break Signal
The telnet break-on-ip line configuration subcommand causes the system to generate a hardware Break signal on the RS-232 line that is associated with a Telnet connection, when a Telnet Interrupt-Process (IP) command is received on that connection. The syntax for this command is:
telnet break-on-ip
Use this command to work around the following situations:
Several user Telnet programs send an IP command, but cannot send a Telnet break command.
Some Telnet programs implement a Break command that sends an IP command.
Some RS-232 hardware devices use a hardware Break command for various purposes.
A hardware Break command is generated when a Telnet break command is received.
In the following example, line 5 is configured with the telnet break-on-ip command. The location text notes that this refers to the high-speed modem. The telnet transparent command sets end-of-line handling.
Example:
line 5
location high-speed modem
telnet transparent
telnet break-on-ip
Besides that, the minimal config needed is:
line # #
no exec
transport input all
As for having difficulty with some devices attached, you need to check the cabling required by the device. The octal cable used for this application is rolled. So , if you attach a coupler to RJ45 and then a cisco blue cable and the RJ45/DB9 adapter in the cisco kit that straightens the cable out to a standard RS-232.
HTH, Erick