I think I'm suggesting for a 10-12 min for a couple of hundred tags somthing is seriously wrong; poorly programmed, designed or bad installation,
This was done by the BMS company with their own equipment. I believe their update times were OK, with the exception of an RS232 serial interface to AC units in the data rooms, switch room etc. I forget what you call them - they are the box type ones usually used in data centres. Why would you use RS232 serial interface to 40 odd of these things and expect the comms to work OK? RS485 or Ethernet would be OK. The system spends half it's time reporting comms errors. Turn a unit off and about 8 of them go out. Stupid!!! That was really bad design on their part.
I believe the fact that the so called SCADA engine I had to hook into was a local product may have a lot to do with it. It was very slow. It also had to handle the very badly designed comms network to the AC units. When I installed the latter driver they had to change the code for the SCADA engine as it did not even have an "online" bit and the new driver would not recognise it without the bit on. Amongst a lot of other discrepancies that I have not mentioned. As I said, I have only mentioned the tip of the iceberg, it was quite a dramatic project. The consultant wanted the BMS done by our company in the PLC system but the mechanical services contractor refused to warrant the mechanical services if the job was not done by his preferred BMS contractor. Not a good place to start. Will have to get together one day and chew the fat.
If you have used BACnet in Ozz, you have probably worked for the company I speak about. They are supoosed to be the "doyens" of BACnet but had non compliant controllers and had to replace them all. The BACnet labs are testing for compliance now but I have not heard that they have progressed to a point where they are testing software. That I why I believe it is an "immature" technology. They are trying to fix the incompatability problems by testing through the labs but it is taking a long time.
When testing was carried out at the Citect offices in Sydney with a BACnet OPC driver, the driver had trouble communicating with this brand of controller. It was tested with two other brands with no problems. The latter two brands had no problem communicating with each other but the preferred, and eventually implemented, brand could not communicate with the other two. Curious!!!
I hope that this indicates where I am coming from. The same brand controllers had no problems with each other, of course, but when another brand or driver was introduced, there was hell to pay. Hopefully the testing labs will sort out the incompatabilities in the sam way that the ODVA have done with Device Net through the testing labs. I will not buy a Device Net device that has not been tested in this way and have never had a problem.