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Strategies & Market Trends : Gorilla and King Portfolio Candidates
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To: spiral3 who wrote (18979)2/28/2000 12:45:00 PM
From: konabound  Read Replies (3) of 54805
 
First, realize that the opinion on Lonworks customer service is based only upon a few companies that I have talked with. Hopefully for some of the larger companies such as Honeywell the customer service might be better.

Second, you are right about the price versus cost savings in terms of the larger companies, but for some of the smaller sensor providers the cost factor can be important. The sensor providers might not benefit from the cost savings as much as the larger control companies will and the customer savings might not flow to the sensor provider.

Now for your technical question. BACnet systems that meet the requirements set forth by ANSI/ASHRAE Standard 135 will be interoperable, but there can be cases where a device is BACnet but might not be fully interoperable with another BACnet device in a few situations. Realize that BACnet was a standard developed by committee with all the compromises that committees can generate. The result of trying to be satisfactory to all the people most of the time makes it unsatisfactory to some of the people some of the time. When a vendor develops a BACnet protocol for their product they must meet one of six conformance classes with Class One being simply a ReadProperty up to Class Six meeting all requirements. Most products usually meet at least Class Three which covers most of the common Read, Write and List requirements. Usually the simple products might only need Class One while major controllers need Class 5 or 6.

BACnet is available as a serial protocol, ARCnet protocol, Ethernet protocol and TCP/IP protocol (which was released in 1999 and will replace the non-TCP/IP Ethernet protocol). Thus obviously a BACnet Serial device would not be able to communicate to a BACnet Ethernet device without the appropriate interface.

Also, in order to compromise to meet the needs of the major vendors on the committee, ASHRAE allowed them to be able to also transfer non-standardized information between devices using BACnet. This enabled the vendors to incorporated some of their proprietary data into BACnet. What this means is that a device might meet all of the BACnet requirements for data transfer, plus also provide additional information that might only be understood by similar products. It can still be interoperable with other BACnet devices but those BACnet devices might not understand some additional data that can be provided. Of course that other device might also not need to know that data too.

However, realize that the same holds true for Lonworks. Two devices might be Lonworks but still not be interoperable because they have different profiles with different SNVTs. In both the BACnet and the Lonworks case this would only be a problem if you were trying to interface two very different devices that would normally not have a reason for interface. In both cases, the interface might be accomplished using a gateway link.

I have probably taken up more bandwidth than I should have here with this response and I apologize for that. Hope this information is clear enough.
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