Michael,
Sorry it has taken me so long to answer your question, have been extremely busy as of late.
The main question I have is: with the push for SEP and standardized Energy Service Interface, don't you think Modbus for meter reading will become legacy within the next couple of years?
To answer this simply, no. Modbus in the power world is THE standard. Ask anyone in the industry what meters they are using and what standard is being used. I am not talking residential markets either, the money is made in larger markets, let google and microsoft scrap it out down below for this so called power standard. There are 20 others springing up daily fighting down below as well. Do I agree with this, well yes and no. You see noone has seemed to bridge the gap very well between the power world, and the automation world. Yes there are modbus solutions, yes there are plc solutions that support modbus, and yes various vendors do parts of this quite well, but none can get one solution for all of this in one package. I know somewhat where you are going above, but remember there are companies that have no interest in broadcasting there usage anywhere besides there own servers. In addition I am sure consumers and lawyers lay in waiting for the day companies begin publishing usage online and scream foul. Where am I going with this??? Quite simply I can go on and on and on, but what I know now is there are thousands of meters in industry right now that support modbus, search ebay and see how many solutions support modbus, now enable read write commands from the the isy-99, and you have the ability to bridge the plc world and the power world, opens up an entire market. Modbus is one of the BEST solutions that you can support because the standard is OPEN to be used by anyone. Every device that uses modbus has registers that are easily read, depending on device can also be written easily, sometimes there are exceptions, BUT the protocol is one of the simplest on the market. Now take serial devices on modbus, they are simply converted to modbus TCP with a gateway. So why do others not use it, honestly because it is probably TOO OPEN. Remember in buisness sharing information between vendors makes it easy for them to implement your solution in their system. Its alot safer for a company to have their own standard and hide behind it with there specific solutions. Is that such a bad thing, for the consumer, and buisnesses it is, but everyone is out to make money.
I am very open to using ModBus Ethernet since it does not require hardware modifications (such as additional ports). Is there a minimum level of support/requirements that can provide the maximum amount of functionality?
YES, you will need to make a map for every device you support therefore you can sell the service based on device...or just let me build the map and it will make me even happier!!. You see modbus has Registers. Holding registers are the 4x registers and are the values that the device is giving back, not OUTPUTS, but values. For instance a voltage would be stored in a 4x register. I can go into detail for input registers and output registers, but google is just as well so I do not waste web space. The mapping behind the device would link to these registers and serve them up. Now what could be done with this, you see you could read the kW value of the house on the ISY, and I could trigger events when it goes over that value, the key is mapping the registers and then storing those values. Mainly kWH for power consumption. In addition kW. I can go on and on, If you want a REALLY good description, or talk about it, just IM me and ill give you a call.
Sorry for the winded response, do not disect it too badly, its late and honestly some of it is opinion, but I am not too far off...[/b]