The CMC control units are used to monitor values of different sensors in the Rack or in the LCP. They can also be used to set critical values. As soon as a sensor reports values beyond a critical value an alert is activated. Such exceeding can be used to switch relays. This is useful to cut the power of a rack, e.g. if the temperature is too high.


The CMC-TC unit is mounted in the racks. It needs a 24V DC power source. Four ports are provided to add Input-Output(IO) units. Each IO unit can has four ports for, e.g., sensors or relays. A ethernet port enables the communication to the outside world.

communication protocolls

The default IP address is


TELNET can be used mainly for configure the network option. Enabling the DHCP requests. The out of the box user name and password is cmc .


FTP is used to download the current configuration files and log files. After logging in with the user name and password cmc one has to enter the directory download to find the files. New configuration files can be uploaded. To do this one needs to login with the user name and password admin . The new files have to be placed in the directory upload . There are two configuration files. One is net.cfg , which can you can edit. It determines the network configuration. Another configuration file is cmc.cfg which is a binary and it contains all the other configurations.


The SNMP port can be used to set names of the CMC-TC unit, the IO-unit, the sensors, the relays, etc.. Critical values can be set which is useful to create alerts in case of overstepping. This couses a sending of traps. The values of the sensors can be read out using SNMP. The default community is public . The vendors UID is . . . .

E.g. setting trap receiver IP:
  snmpset -c public -v1 172.25.1.$i SNMPv2-SMI::enterprises.2606. s


The CMC-TC units comes with a web server which can be used to do essentially the same configuration as with SNMP. Furthermore, some logic can be programmed, such as a relay has to be switched, if the temperature sensor reports temperatures higher than the critical value. This configuration can be saved by downloading the cmc.cfg file from the internal FTP server.

CMC-TC basic

The CMC-TC basic control unit is somewhat simpler and it is mounted in the LCP. It has four ports which can be used to connect sensors or relays to it. It needs a 24V DC power source and has a ethernet port. In general, it controls the in- and out-going water temperatures as the in- and out-going air temperature. In- and out-going means in before and after passing the heat exchanger. Also the water flow rate can be measured and, consequently, the carried away heat is calculated. It can monitor the status of the fans and alerts in the case of failing.

communication protocols

Also here the default IP address is


It has the same functionality as the in the case of the CMC-TC unit. The user name and the password is cmc .


FTP can only be used to download the log files. No configuration files can be uploaded. The entire network configuration has to be done using TELNET. The user name and password is cmc .


With SNMP the water and air temperatures are monitored. Critical values can be set and, if sensors or relays are used, they are controlled. In behaves similar as the SNMP port for the CMC-TC control unit.

OIDs for the CMC unit:
OID Meaning Comment
SNMPv2-SMI::enterprises.2606. Door status 0: open; 1: closed


The internal web server serves pages with a nice layout. It shows water flow and temperatures and the status of the fans. In the case of attached sensors and relays they are configured as in the case of the CMC-TC unit. The standard user name and password is cmc . In order to manipulate some special configuration one needs to use admin as a user name. The password is some what complicated and can be figured out by reading the manual of the CMC-TC basic manual. These configuration are not particularly interesting, since the are of the quality: specific heat capacity of water.

firmware update

The latest firmware so far has the version v6.12. Using this firmware allows it to set the fan speed to zero in the case of a cooling system failure. The fans consume 2kW which heats up the system. Now, this can be avoided. Basically it includes the kernel uImage_cmc-pu2_2006-01-30_ppp_mkr , the kernel cramfs_cmc-lcp611.img and a bunch of scripts.

After starting the box a uboot boot loader is started and, usually, the system runs into a BusyBox Linux. The boot loader and the boot process can be viewed using the serial console on the front side of the CMC. E.g., the program gtkterm allows an interactive communication with the serial interface.

There are two ways of updating the firm ware.

via TFTP

The boot loader can be interrupted by pressing enter immediately after powering the CMC unit.

With help one can list the available commands of this boot loader.

printenv shows all valid environment variables

In order to use a TFTP server use the following commands:

  • setenv serverip ip address of the tftp server
  • setenv ipaddr ip address of the box
  • tftpboot server_ip PATH /uImage_cmc-pu2_2006-01-30_ppp_mkr
  • set cramfsimage cramfs_cmc-lcp611.img
  • set bootfile uImage_cmc-pu2_2006-01-30_ppp_mkr
  • save
  • run updatel
  • run updatec
  • boot

After the system is booted cleanly you should be able to take a look onto the web page. Do a reboot and enter the uboot menu again.

Do the at least the following setting

  • setenv flashargs setenv bootargs root=/dev/mtdblock3 ro
  • save
  • boot

via the ftp server of the CMC

Login on the ftp server of the CMC. The default user and password is admin . After loging out the CMC reboots automatically. Wait several minutes, until the CMC unit comes back.


  • hash
  • binary
  • cd upload
  • put update612.tgz
  • put
  • put update
  • quit

This seems sufficient. Anyhow, if not try the next stage and if everything fails you have take this unit and do the tftp procedure.

login again:

  • hash
  • binary
  • cd upload
  • put eraseall
  • put copy
  • cd ..
  • cd download
  • del .
  • put reboot
  • put cramfs_cmc-lcp611.img
  • put uImage_cmc-pu2_2006-01-30_ppp_mkr
  • put
  • put checksum1
  • put update_l
  • quit
Topic revision: r3 - 18 Nov 2009, HenningPerl
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