"A truly successful algorithm would enable the average Kmart shopper to purchase and install a basic Home Plug and Play product without the need of consulting a professional installer or dialing 1-800-I-M-STUCK."

Home Plug and Play Plugfest One

Brian Baker

Home Plug and Play Plugfest One
by Brian Baker

"A truly successful algorithm would enable the average Kmart shopper to purchase and install a basic Home Plug and Play product without the need of consulting a professional installer or dialing 1-800-I-M-STUCK."

The drive from the Orlando airport to the hotel in Ocala, Florida had provided a feast of greenery for these eyes so used to the sparse vegetation of the desert southwest from whence I had come. I appreciated the distraction from the anxiety I felt about the next few days. So many man-hours had been invested in bringing us (the developers of the Home Plug and Play specification) to this critical point. For me this included spending the last 4 to 6 weeks translating written specifications to firmware operating in an actual product. A Home Plug and Play product. I had carefully packaged up two identical units and the box was now sitting in the back seat of my rental car as I drove this last leg of the trip to Ocala, Florida.

When questioned earlier that day by security personnel at the El Paso, Texas international airport about the contents of my package, I made the mistake of answering with: "Some Home Plug and Play products for use at a Plugfest!". I didn’t help things any in my attempt to clarify that the box contained some home automation products. Tapping into my experience over the past few years I realized the only reasonable thing to do in this predicament is to say "its a box of electronic stuff.". It was bad enough a few years ago when people would ask me what I did for a living and I found myself attempting (unsuccessful, if I might add) to describe what a C programmer of embedded systems is. Now that I have moved on to be a systems engineer for a company developing home automation products and a co-developer of the Home Plug and Play specification, I find myself even more alienated from the current mainstream. Home automation is not even listed on the annoying cards that I occasionally have to fill out to maintain my free subscription to engineering periodicals. Enter stage left, Home Plug and Play; a new name appearing in the infancy of this soon-to-be giant industry. Will it move on to a center-stage position?. After what I experienced at Plugfest 1, I returned home with firm expectation that the Home Plug and Play label will soon become a sought-after identifier for manufacturers to place on the packaging of consumer electronic products.

As I entered the conference room of the hotel in Ocala that had been acquired for this first Home Plug and Play Plugfest, my ears homed in immediately to a familiar sound. I have been in many hotel conference rooms over the last 3 years for technical meetings related to the CEBus standard, but it was this steady 60 Hz hum from a large isolation transformer in the corner of the room that impressed upon me that this gathering would be different from any I had experienced heretofore. Use of a low-pass-filter/isolation-transformer combination is necessary when CEBus communication packets must be limited to a particular segment of the powerline medium. Such was the case in this room where there were three powerline networks isolated from the rest of the A/C power in the room. The presence of these transformers underlined the expectations I had that this gathering of engineers would turn out to be a real role-up-your-sleeves kind of event. Representatives from 8 manufacturers were expected to participate in this two-day event; some had already claimed the available table-top real-estate provided for setting up our individual products. Spread out before me was an assortment of personal computers, home-automation products and prototypes. Some products had been under development for years while others represented prototypes of products only conceived in the past few months. After finding and setting up another folding table, I unpacked my box and set up for the next two days of tests for product interoperability.

Plugfest 1 - Day One

The following morning we began a series of tests for interoperability in the critical area of House Code propagation.. In an effort to realize the plug-and-play aspect of the Home Plug and Play specification, the development team had invested a significant effort in designing an algorithm that would simplify product installation. A truly successful algorithm would enable the average Kmart shopper to purchase and install a basic Home Plug and Play product without the need of consulting a professional installer or dialing 1-800-I-M-STUCK. This was a formidable task when you consider some of the real installation scenarios that are idiosyncratic to using the powerline as a communication medium. Consider, for example, what happens in a large apartment building where everyone essentially shares the same electrical service, yet each apartment is virtually a separate household. Installation of a newly purchased Home Plug and Play product should not suffer from interference by other products in the other apartments communicating on the shared powerline. Our initial tests were conservative, consisting of a single product from one manufacturer combined with a product from another manufacturer. Little by little we progressed in installation complexity, finishing day-one with a full-house installation of all the products present. In most cases the installation of a device was indeed plug and play, requiring only a simple press of a button to cause the device to begin interoperating with other devices on the network. Successful plug-and-play installation of a home network consisting of products from diverse manufacturers represented a major milestone in the establishment of the utility provided in the Home Plug and Play as a specification.

Plugfest 1 - Day Two

As we gathered in the morning of the second day, the group discussed the focus of tests for this final day. We agreed to utilize one of the available test networks to continue exercising the initialization and configuration algorithm implementation of some products. Though we had demonstrated the previous day that the House Code propagation algorithm worked as designed, it was apparent that some implementations needed some fine tuning.

We continued throughout the day to add to a list of issues we had begun compiling the previous day. This list would serve as a guideline to us later on as we worked to finalize version 1.0 of the Home Plug and Play specification scheduled for release early in October.

Coincidental with the continued configuration related tests on one network, a second network was utilized to test implementations of the Home Plug and Play concept of network resources that some manufacturers had brought with them. Products generally fall in one of three categories related to network resources:

  • (1) Resource Providers,
  • (2) Resource Subscribers and
  • (3) Resource Independent.

Products in the later category do not participate in network resource related activity of the network. Products can provide one or more resources while also subscribing to a plurality of resources from other providers. The products tested on this second network had implemented the capabilities of a resource provider and/or a resource subscriber of the ubiquitous network resource: time-of-day (TOD). Many consumer electronic products utilize TOD as part of their internal control algorithm or as information to be displayed to the user. The Home Plug and Play specifications defines several types of the TOD resource that are grouped by either the degree of precision or the identity of the source of the TOD. Our test scenarios included products acting as would-be subscribers requesting a subscription to a particular type of time, such as that provided by a product having identified itself as a provider of TOD from an Electric Utility company. It was truly rewarding to observe interoperability demonstrated by TOD synchronization amongst products developed by different manufacturers. Though not an example of rocket science, TOD synchronization and recovery of correct TOD after a power outage is one of those bells and whistles that home owners may well become so accustomed to, that they will grow very sensitive to the absence of this feature in non-Home Plug and Play products.

Another important scenario tested on the second network was related to the Home Plug and Play system feature of House Mode vectors. Periodically, products supporting this feature will broadcast to the other Home Plug and Play devices on the network a vectored message containing the current mode of the house. The vectored format provides a means of presenting the current mode of the house in a hierarchical manner so that products can receive this information over the network and process it to the level of detail they understand. An example of House Mode vectors would be the vector Occupied-Asleep as opposed to the vector Away-Shopping-Kmart. Many devices would stop processing these examples of house mode vectors after the first level of information was parsed because they can only understand the concept of away or occupied. For instance, the home heating thermostat could deal with the information that the home owner is away or not. However, the information that the owner is shopping at Kmart is of no interest to the thermostat - unless maybe he/she is shopping for a new thermostat.

What’s Next

Around the first week of October, the CEBus Industry Council (CIC) will be releasing version 1.0 of the Home Plug and Play specification. This release will include resolution of issues identified during this Plugfest 1 held in Ocala. On November 18th through November 20th, Smart Corporation based in Las Cruces, New Mexico will host Plugfest 2. The goal of this second gathering is to actually walk away with a level of certification for product developers so they can utilize the Home Plug and Play mark/logo on their product packaging and in advertising their products. I encourage you to obtain a copy of the Home Plug and Play specification and jump on the bandwagon. Two more Plugfests are in the planning to occur before this time next year. One of them will coincide with CIC’s annual CEBus developers Conference in the spring. Those who are interested in participating in any of these events should contact the CIC at their web site: www.cebus.org

Updated Biography Mar/03 - Brian Baker is a software engineer at Raytheon Missile Systems located in Tucson Arizona. He was a contributing member of multiple committees and working groups of the CEBus Industry Council while employed at Smart Corporation previous to his joining Raytheon. His background includes development of home automation subsystems and over 15 years of embedded systems development in the defense industry. He was a core member of the developers of the Home Plug and Play specification. Brian can be reached at bdbaker@raytheon.com

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