The CM11A supplied with X10 (USA) Inc. ActiveHome and IBM Home Director products can be used with HCA.  This device has a number of good features - it's small and self powered.  There are no parts required except a cable to connect the CM11A to the computer's serial port. 

Besides being just an X10 interface, the CM11A also contains a very simple processor and some very limited memory.  This is used by the ActiveHome and Home Director to program the CM11A and then allow it to be disconnected from the computer and have it operate in "autonomous mode".  HCA does not use the memory of the CM11A because its capabilities and memory are very limited.  It is not possible to perform HCA schedules, programs, and groups by using the processor and memory in the CM11A.  When using the ActiveHome and Home Director products, if you have just a few devices and schedules for those devices you will run out of memory in the CM11A and will then not be able to use the CM11 autonomous mode.

The bad news about the CM11A is that it sometimes does not work and "falls asleep".  That is, sometimes it does not respond to commands sent from your computer.

The CM11A is also susceptible to power line problems - spikes and sags.  If you are in an area of the country that experiences frequent power outages, you may want to consider one of the Marrick Limited controllers which are much more tolerate of power line problems.

Some problems with the CM11A are: it may appear to be dead on arrival,  it 'dies' after a long period of good behavior, or it fails to work after being moved.  This can be most aggravating, especially when you think that you understand how to avoid these problem, but still it seems to insist upon staying in it's 'comatose' mode.

The CM11A is also given the HD11A part number when sold by IBM.

Please note that the new HD11 now being offered with IBM's Home Director system is supposed to fix the following problem. As of this date, there is no data either way.

How to revive a CM11 without going into a technical description of just what is wrong

If your CM11 failed while in operation, then it is possible that you can wake it up with any command from a remote keypad or anything else that sends X10 commands - like a motion detector.  Sometimes this is enough to wake up the CM11, but not always. If HCA still can't send commands, then you must go to the next step.  But make sure you try this first, you can use a X10 mini controller, its the easiest revivification process and has a high success rate.

You must follow these steps precisely - the order of operations is important!

1. Unplug the CM11 from the wall socket
2. Remove the batteries (not needed by HCA and should not be present)
3. Unplug the serial port cable
4. Leave the CM11 disconnected for at least 15 minutes
5. Only after this period plug the CM11 into the wall socket
6. Reconnect the serial cable
7. Using the Test Hardware Connection button (HCA properties dialog)  to see if HCA can now communicate with the CM11
8. If you still get an error, repeat steps 1 - 7 but wait longer in step 4.  Some units may require an overnight rest.

Note: It matters that the CM11 is plugged into the wall socket before the serial cable is re-connected.

If you have followed the procedure, and even an overnight's rest does not revive the CM11, then it is possible that it is 'dead'. If you just received the unit, and you have never seen it work correctly, then it is most likely 'dead'.

If you have been using the unit successfully, and now it just doesn't seem to be responding to the above procedure, then it is possible that it is 'dead', but this is very unlikely.

The record shows that in the most exasperating cases, it is usually a failure to follow the instructions completely. Other vendors of software that use the CM11 report that exasperated users have sent CM11s to them and magically, they work right out of the box.

How to avoid this problem

The CM11 insists that it get respect so when installing or moving it, always follow the above procedures.  You can verify that it talks to HCA by the Test Hardware Connection button.

If you haven't moved the CM11A or detached and reattached its cable and it stops working in the middle of the night, then it has gone to sleep.  The best way to prevent this is that it must  be occasionally 'stroked' to keep it alive.  That is, the CM11 needs to 'see' any X10 command from the power line or it will fall asleep. It may take as little as an hour, or as long as a day, but unless it receives some X10 command soon, it will fail.

What we have found, is that those users who report NO problems with their CM11, are also those who have the largest systems, and several motion sensors.

Outdoor motion sensors, and those which detect occupants moving around at night, are just the things that keep the CM11 awake.

If you have an old CP290 around, or even the X-10 "Mini-Timer" you can program the CP290 or the Mini-Timer to issue periodic commands.  With the CP290, you could send one every half hour or so, but the Mini-Timer can issue only 8 commands per day, or one every 3 hours. This may be sufficient to keep the CM11 happy, and requires no computer to program it.

By the way, none of this makes any sense to us either. How a piece of hardware can behave in this manner and how it could be sold in the first place seems like a bad dream - computers are just not supposed to work like this.  The above steps and procedures may seem like black magic but experience has shown that they do work.

Remember also that HCA can use the hardware supplied by Marrick Limited.  While somewhat more expensive their LynX series of controllers are very reliable and don't fall asleep on the job.

Much of the information in this article was written by Sand Hill Engineering, the maker of a Home Automation application for the Macintosh, and used with their permission.