This blog post has been contributed by Carl Kagy, Phil Webster and Kalyani Khobragade from CMC team.

The Dell Chassis Management Controller (CMC) allows you to utilize its serial connection to deploy, monitor, configure and update the chassis components. You can use it to perform extensive management actions with the Racadm CLI tool. 

This blog will show you how to connect to the CMC serial port. This connection can be used to drill through for access to the server COM ports within the chassis. 

 A typical scenario for use is shown below 

 

As shipped from the factory, the CMC serial port is enabled.  The CMC serial port default settings are 115200 baud, 8 bit data, no parity and one stop bit (115200,8,n,1). The workstation serial port settings must match the CMC settings. You must connect to the Active CMC (denoted by the blue LED) on a chassis that has two CMCs.

You will connect a null modem cable from the workstation serial port connector to the DB9 connector on the CMC as shown.The CMC requires hardware flow control signals, as shown below.  Use of flow control guarantees complete transfer of all characters.

 

Once the cable is connected and your terminal emulation application is running on the workstation, tap the return key once or twice.  You should see the CMC login prompt.  Login to the CMC.  You can display the serial port settings with the "racadm getconfig" command as shown below.

 

The settings can be changed using the "racadm config" command; however, the workstation serial settings must be changed to match!  Alternatively, the settings can be changed through a network interface such as telnet or SSH, both of which offer the same CLI as the serial port.

To connect to a server, use the "racadm connect" command as shown in the screenshot above.  When finished with the session to the server, type the escape sequence (by default "<ctrl>-\") to return to the CMC command line. 

Some of you will want to connect with the ability to handle all binary data, for debug sessions.  Use the "-b" option of the "connect" command for this.  Note that you cannot use the escape sequence in a binary session.  You must reset the CMC to break the session.  On a chassis with two CMCs, resetting the CMC will cause the other CMC to become active (it will show the blue LED).  You will need to move the cable over to the other CMC.  To avoid this, you can temporarily remove the second CMC until you have completed debugging.

Now that you have access to the serial port, you can use server OS facilities for debug and configuration.