The CM11 plugin has been updated for Catalina and newer OS versions as of XTension version 9.4.34.

Unfortunately the CM11 is no longer made by X10. There are still plenty that show up on ebay and other places but for a modern replacement you should consider the XTB-232 which is a drop in excellent replacement.

The CM11 is an X10 powerline protocol interface. It can talk to any of the X10 powerline modules.

It is a serial device so it will require a Serial Adaptors

The CM11 has been around a long time and has an excellent track record, it is also available from many online retailers or ebay sellers very inexpensively.

XTension supports multiple interfaces and multiple CM11's may be placed around your house to improve signal reception.

Because the CM11 is a low speed serial device the connection between the USB/Serial adaptor and the interface can be extended easily through inexpensive cable such as CAT-5 cable for long distances, or with the addition of RS-432 converters for many hundreds of feet to get them where they need to be.

The CM11 advertises the ability to perform limited functions even without the computer connected. XTension does not support downloading simplified instructions to the CM11 and must remain running. You should not put batteries in the CM11 when used with XTension, every so often a cosmic ray will hit it's chip and cause it to send out a signal on a regular basis that will drive you crazy to find until you take the batteries out.

CM11 support is included in XTension, no plugins or additional software or licenses are required.

As of this writing (3/9/2009) the CM11a cannot be connected wirelessly via the IOGear bluetooth/serial adaptor. It almost works and further experimentation may resolve the problems, but at the moment this combination isn't likely to work.

The CM11a can be connected through wired TCP/Serial interfaces like that built into the Barix Barionet devices. Xtension can NOT automatically set the serial port settings on the Barionet interfaces, so you will need to set the Barionet RS-232 serial speed to 4800 baud, and confirm other default settings of 8 bits, no parity, 1 stop bit; and reboot the Barionet to use the new settings. With incorrect baud rate, Xtension will report “CM11 successfully located” and then “CM11: Error 35 - No response from the CM11” and “PM Interface error: (Power Failure at controller)”