How do I send a break signal to a serial device connected to a UDS or other CoBos based device server?

<--- This answer applies to all products listed on the left.

Here is a typical setup:

+------+        +----+               +------+
| SUN  | Serial |UDS |   Ethernet    |Local |
|System|--------|    |===============|System|
+------+        +----+               +------+
              192.168.5.2       

Enable Telnet Mode on the UDS's serial port from the web manager or Setup Mode.  For instance, in Setup Mode:

• Type 1 to open the Channel 1 configuration script
• Hit Enter until you get to Disconnect Mode
• Change the value of Disconnect Mode to 40
• Hit Enter until you're back at the menu
• Type 9 to Save and Exit

To pass a break from the Local System to the remote Sun system you will need an application that can send the telnet IAC command "send brk".  This sends the telnet IAC string 0xFF 0xF3 to the UDS's serial port.

For instance, in Microsoft Telnet type Ctrl+] to go to the Microsoft Telnet prompt, then type 'send brk' and hit Enter twice:

C:\Documents and Settings\gary>telnet 172.18.11.189 10001

<type Ctrl+]>

Welcome to Microsoft Telnet Client

Escape Character is 'CTRL+]'

Microsoft Telnet> send brk
Sent break
Microsoft Telnet> <press Enter to return to telnet session>

This same method will work on Linux and Unix machines, but you only have to hit Enter once to be returned to the telnet session.  Here is an example from Fedora Core 6:

[gary@localhost ~]$ telnet 172.18.11.189 10001
Trying 172.18.11.189...
Connected to 172.18.11.189 (172.18.11.189).
Escape character is '^]'.

telnet> send brk

Other Windows telnet clients have the ability to send the telnet 'send brk' IAC string, including the free TeraTerm, available from http://hp.vector.co.jp/authors/VA002416/teraterm.html.  In TeraTerm type Alt+B to send a break, or pull down the Control menu and choose Send Break.

[Originally Published On: 06/11/2007 12:46 PM]