BACNet

Anyone on this forum using BACNet? I'm looking for some info as to typical applications and as to what transport (MSTP, IEEE 802.3, UDP, LonWorks etc.) is most common...

I'll get back to you after 2 weeks after my BACnet-training.
Tmu

Mike,

We have done some research into BacNet as a protocol for a new controller, whereby we would incorporate a third party device as part of our new controller.

It is primarily a protocol used in building automation.

I am not 100% certain but I believe you can have it as an ethernet, MSTP or serial interface.

Lonworks is an entirely different protocol.

I don't know if this is what you are looking for.

God Bless,

Got "caught" with BACnet some years ago. A SCADA system I programmed used a BACnet OPC server to hook into the BMS system. Damn thing did not work properly. They still have problems after the BMS people have been in to "clean up the system". But the BMS people can find nothing wrong and all of a sudden it starts to work again. The cry from the BMS people is "we did not touch or change anything". YEAH!!!!! I think they are all trained by Honeywell.

Be very careful and make absolutely certain the hardware has been fully tested by the BACnet testing labs or you may get caught like I did. The BMS people kept blaming the OPC server and the SCADA system for any problems, of course. At the end of the day, only took 18 months, a guy from the company who supplied the BACnet OPC server had a quiet word with the BMS hardware people at a BACnet meeting. Some hardware was provided for testing to the software guys. It turned out that the b****y BACnet hardware was not fully BACnet compliant. They had to change all their controllers!!!!

The OPC server I used runs as a "service"? or layer on Ethernet at 100megs. It is painfully slow. I am a PLC man and expect to see things in my SCADA straight away. The PLCs I used were dragging info from AB Powermonitors via explicit messaging on Device Net and then onto the network and into the SCADA. I was seeing updates about 3-4 times a second. Digital I/O from the PLC system was about 20 milliseconds. The network is a token ring based network, is reliable and predictable. In other words, not Ethernet!!! The BACnet OPC server was taking up to 5 minutes to interrogate the BMS system and return results to the SCADA. The PLC system was on line in a fraction of a second!!! Huge difference.

By the way, there were only about 700 I/O from the BACnet system being read into the SCADA. The PLC system had over 2500!!! Citect was reporting over 15,000 digital reads per second fropm the PLC system. The network was only running at 2megs!!! Device Net only running at 750kbaud!!!

Not impressed with BACnet at all!!!!! Maybe it has improved since 1998.

BobB said:

Not impressed with BACnet at all!!!!! Maybe it has improved since 1998.

Click to expand...

now now Bob please dont bacnet bash for 1 poor install/supplier!!!

I have seen it do some amasing things and have found that 99%
of any issues have been human related.

Thanks for the replies, guys. The reason for my question is that we've been seeing a lot of enquiries for BACNet with our HMIs, so we've gone ahead and added support for BACNet over RS485 (the so-called MS/TP transport) and over Ethernet using IEEE 802.3 frames to our G3 panels and our Data Station Plus. (We're working on BACNet/IP and we'll have that as soon as we can figure out how to get the bloody kit we're working with configured!) But we're not sure about the LonWorks transport, which can also be used to carry BACNet frames. We've had some questions about it, but supporting it would mean an expansion card to handle the hardware side, which is obviously more of a commitment than software, which, as we all know, is free (joke)...

Hi Mike, a few links that might help;

http://bacnet.sourceforge.net/

http://www.polarsoft.biz/bactrace.html

http://vts.sourceforge.net/

http://www.chipkin.com/a/resources/BACnet/

Thanks, Tripper.

now now Bob please dont bacnet bash for 1 poor install/supplier!!!

Click to expand...

Not a bash an accurately stated fact of life.

I have seen it do some amasing things and have found that 99%
of any issues have been human related.

Click to expand...

Obviously I have seen it do some amazing things also and continue to do so. Please note that all the hardware is now fully BACnet compliant, the OPC server is fully BACnet compliant but the damn thing is still so slow it is painful. Where is the human related issue here?

Give me PLCs any day.

BobB said:

but the damn thing is still so slow it is painful. Where is the human related issue here?

Click to expand...

forgive me if I'm wrong has been a couple of years since I programmed Bacnet
Human related:
Network performance
Poor network design, overstressed 485 network, no repeaters, poor termination, incorrectly fitted hubs/switches, no end of line resisters on 485, screening/earthing, cable runs etc etc
Software config:
Poor controller/point config
As you're prob aware each variable can be config as polling or COV (change of value) for point passing between controllers and if left as COV the network can become clogged..actually on this point, I think the PLC networks have reduced the risk of end user configering a network wrong which Bacnet software writers could learn alot from.
anyway I could go on and on but about to go on holidays!!!!
I hope you didnt take it the wrong way.