Exploring ANSI standards in meter communications
The ANSI protocol standards will reduce the cost of supporting metering operations and accelerate the rate of innovation and change within the metering industry. Participants from both the supplier and user sides must advance with their eyes open or fall behind their competitors. The greatest advantages will come to those who have the best access to the highest quality information. Electric utilities and others who purchase and apply meters must consider these new standards in order to optimise their operations. The keys to success are timing, and intelligent selection from the array of new tools coming onto the market.
With electromechanical meters, collecting data was easy. It consisted of someone visually reading a couple of 3- to 5-digit values from standardised dials, manually recording the value on a billing form, and returning it to the utility for transcription and bill generation. In some co-ops and municipalities, the customer might even have read his own meter and sent the reading in on a postcard.
The advent of more complex rates and electronic registers resulted in changes to the method of data collection. The dials were replaced by displays, which scrolled through selected data values only, while most of the information remained inside the meter for retrieval via a communication tool.
Each style of electronic meter communicated using its own protocol to provide internally stored values in formats unique to each manufacturer. A new meter design usually resulted in some different control parameters or values being added, some values being recorded in new formats, and all being transported with a ‘slightly modified’ proprietary protocol.
Today some meters store hundreds of thousands of pieces of metering data. The microprocessors used in these meters vary from small 4-bit micros to Intel® Pentium® chips. Many moderately priced meters today go beyond conventional metering to analyse the service at which they are installed, adapt to that service, and even notify the installer if the service is mis-wired.
While handheld readers are still used, an increasing number of meters communicate directly with AMR systems. The users of these legacy meters are burdened with multiple computer systems from different suppliers using dozens of proprietary protocols to communicate with the user’s meter inventory. Utilities are required to buy separate software from each meter manufacturer in order to program options in these meters. Third party handheld readers and metering systems have to be updated for every new meter type added to the mix. Only those who can obtain a licence from meter manufacturers can even develop software to read the meter.
Several years ago the ANSI, AMRA and Canadian Standards bodies got together in a series of meetings called Tablefests. Their objective was to develop a solution to the increasing obstacles for meter communications. After five years of intense work – involving over thirty utilities, all of the North American meter manufacturers, several third party software providers, a number of consultants, and several other interested parties – three significant ANSI protocol standards have emerged and a fourth is on the way.
What are the ANSI protocols?
The ANSI protocols are a set of simple but flexible protocols aimed at a wide range of metering products. They were developed by the ANSI C12 Electricity Metering Standards Committee in co-operation with the Automatic Meter Reading Association (AMRA) and Measurement Canada (the Canadian standards body).
The standards are aimed at a variety of metering products, including, meters, recorders and add-on modules. As a result, the standards all refer to this class of metering related products as end devices instead of meters. Care was taken to be compatible with the needs of water and gas industries as well.
The standards include:
ANSI C12.18-1996 Protocol Specification for ANSI Type 2 Optical Port: This standard is a very simple transport protocol (layers 1 though 7) designed to transport data structures as defined in C12.19 via the infra-red optical port currently in use by most North American electricity revenue meters.
ANSI C12.19-1997 Utility Industry End Device Tables: This standard defines a set of flexible data structures for use in metering products. The standard also defines a Pascal-like syntax for identifying and describing these structures. In order to support innovation, the standard allows for inclusion of manufacturer-defined tables, which can also be described in this same syntax.
ANSI C12.21-1998 Protocol Specification for Telephone Modem Communication: This standard extends C12.18 and C12.19 to accommodate modem communications at the meter.
ANSI C12.22 – Protocol Specification for Interfacing to Data Communications Networks: This working draft for a standard extends C12.18 and C12.19 to support data network communications at the meter. The work is currently advancing under the joint involvement of NEMA/ANSI, AMRA/IEEE and Measurement Canada.
These standards promise lower meter operation costs and simplified meter interface processes. Common protocols and similar structures give meter purchasers greater ability to exploit the functionality of the meters they buy. Historically the lack of open standards meant that many electronic meter capabilities remained hidden and were seldom, if ever, used. The standards enable a new openness in metering that has not existed before. Many options and features that were closely held by meter developers will now be open and available to the purchaser or software developer, who may want to take advantage of them to optimise their operations or for commercial benefit.
The standards also provide a common vocabulary to describe meter capabilities. Users, learning about manufacturer A’s standard protocol meter, have a much higher potential for using that knowledge when they consider manufacturer B’s meter. Legacy meters are described in unique terms, defined by each meter manufacturer. Now a ‘negotiate service’ (part of the communications start-up process) will mean the same thing to all meters, no matter who manufactured them. Data structures are defined as ‘tables’ and all commands and functions are referred to as ‘procedures’. Self-describing data structures let users read the meter to find out what parameters measure kWh and which are kVARh. Common data structures for familiar functions follow the same rules. This keeps meter personnel from having to adjust mentally every time they switch between products manufactured by different companies.
The standards also allow a single software set to perform common programming and data retrieval processes on meters designed independently of the software developer. In other words, utilities or third parties can more easily write useful software to exercise ANSI protocol meters with little or no assistance from the manufacturers of those meters.
In fact, most meter firmware that has been developed to date for products using these ANSI protocols has used a common, commercially available test software package for conformance tests. This commercial software, Table TstBench® from NERTEC, handles both standard and manufacturer-defined ‘tables’ and ‘procedures’. Use of this capability means that the time between acquisition of a new meter and being able to use it effectively can now be collapsed to seconds, rather than weeks or months. It also enables the purchaser to evaluate sample meters at a rapid pace.
This use of common software by very dissimilar ANSI protocol meters encourages innovation. It allows manufacturers to introduce new features and products without the costs or delays currently caused by having to keep software up-to-date in parallel. The parsable data description syntax that allows this is found in ANSI C12.19.
These standards are written to allow manufacturers to evolve their products toward the standards, as well as to encourage innovation beyond the standard. Mechanisms exist to allow the addition of these innovations in subsequent standard revisions as they achieve market acceptance.
What’s Happening Now
The market pressures for ANSI protocol meters (APMs) have reached critical mass. Initial opposition by a few suppliers is dissipating as they sense a change in the marketplace and prepare their own ANSI protocol products. While some less progressive manufacturers of meters and software tools may attempt to delay broader acceptance until their products catch up, leading manufacturers will be ready to meet the increasing market demands.
The entire Canadian market is closing to new meters that do not meet the ANSI C12 protocols for both transport and data structures.
In California, the Public Utilities Commission has required the use of the ANSI transport protocol C12.18 in the deregulated market. Other states in the deregulation process are expected to follow. Strangely, the California Public Utilities Commission did not require C12.19, the AMRA tables standard. The C12.18 protocol, however, was written specifically to support the AMRA tables, so moving products to C12.18 without C12.19 becomes a waste of development resources.
Several utilities, led by Southern Company, have made the AMRA tables a meter procurement requirement. An even larger number of utilities and ESPs have declared preferences for APMs, but have not taken as strong a stance as Southern Company.
Major meter manufacturers cannot ignore these markets, which now require or give preference to ANSI protocols, and still maintain their market shares. Niche meter manufacturers also risk turning their niches into dead ends if they don’t pay attention. The leading meter manufacturers currently appear to support or be moving toward support of the standards. It is anticipated that the newer meters should embody more complete implementation of the ANSI standards.
In any case, imminent announcements of innovative new products should break the dam and further accelerate the move to APMs. In anticipation of these pending product offerings, some analysts expect a switch to APMs from current proprietary protocols at a rate faster than the earlier switch from electromechanical to electronic polyphase meters.
Support software is another issue. Utilities are looking for software systems that support the APMs. Historically, software concerns occurred almost every time a new meter was introduced. One of the main reasons that the ANSI protocols were pursued by utilities was due to the delays and fees for incorporating the ability to communicate with new meters into data collection software. A second reason was the need to maintain and support software systems unique to each meter manufacturer. The work by NERTEC in its Table TstBench® software has proven that APMs should greatly reduce the need for these software changes in the future. There is evidence that several systems are being modified to support APMs. Since software can now be written to communicate effectively with these meters without licensing, it is expected that meter manufacturers will also enter the third party software market in a major way.
Selecting ANSI Protocol Products
Inclusion of some services in C12.18 and most tables in C12.19 is optional. Use of the standard must therefore be reviewed carefully before purchasing APM meters.
Minimal compliance with these standards is simple, while very broad compliance is more difficult for manufacturers. Yet the value to the purchaser should be just the reverse.
The Southeastern Electric Exchange has reviewed the standards and published a guideline useful in this evaluation. An easier general guide is to adapt the policy that states: “If the standard covers a functionality, the meter should do it the standard way.”
Product manufacturers will each select which portions of these standards to support, which portions to replace with their own creations, and where to extend the standards.
Electricity deregulation, as well as utility issues dealing with multiple meter vendors and software platforms, will also affect the choice of products and tools.
ANSI protocol meters and a limited set of tools have been in the market for over a year. More complete meters and tools to fully support them are on the way. To take advantage of this next paradigm shift in metering, the suppliers and potential users of this technology must position themselves to take advantage of a surge in the use of these meters beginning in the third and fourth quarters of 2000. This offers a win-win situation for the intelligent participants, and a lose-lose for those who delay entry or blindly grab any offering without close examination.