Integrating Alerton site...Remove BCM's or not?
Have a 10 year old school with about 6 MSTP trunks, the 6 existing BCM's mainly serve only as link routers using subcall routines (and stores the usual schedules/zones, etc).
I am being told that the BCM's provide more than just routing functions, and the Alerton controllers communicate better when BCM's are used. My boss wants the BCM's removed and Jace 7's to take place of 'em for no reason other than if something breaks in the future, we don't have to deal with making software changes.
I've done both on smaller sites, it seems like the overall performance of the network is better when the BCM's are left alone to do the link routing. Many of these MSTP trunks have more than 32 devices.
Should we leave the BCM's in place or remove them?
Thanks for any feedback...
I would leave them in place. The network performance is better and the load on the jace is much less. If a BCM dies you could always put a Contemporary Controls BACnet router in it's place. It is a lot of work to replicate the subroutine type programming in the BCM in the jace.
If something breaks in the future with JACE's installed, you will have to deal with the exact same issues. There is really no reason to spend a bunch of money to change something that works. Jaces sometimes can't handle the amount of MSTP controllers that Alerton can (Their RS-485 driver stack is wimpy), so keep that in mind... If we have to put a Jace on top of an Alerton system we leave the Alerton Global in place, just use the Jace to host graphics / trends / Alarms. If he's dead set on removing the Globals, and you do have a heavy MSTP load, Contemporary controls makes a MSTP->BACnetIP router that will handle that load nicely, and the Jace will still control them, but using it's Ethernet port, instead of it's RS-485 port.
A CC Bacnet MSTP to IP router doesn't have an issue with Alterton, but a Jace running Bacnet/MSTP does? Never pulled in Alerton, but I have run 4 MSTP trunks to a single Jace multiple times and thought it was a mad machine at bacnet. No problems, fast response, tuning policies required. A CC router is only going to handle 1/4th of that....
Are you sure its a Jace bacnet issue and not something else?
How much logic are you putting in the Jace to replace an "A-box"??
If this BCM fails are you still SOL? Why not bite the bullet and reduce the number of obsolete controllers in the system if possible.
No, a Jace has no issue with Alerto;n - it's an issue with overloading the MSTP trunk. The Jace slows down significantly under heavily loaded trunks. Split the load onto 2 Jaces, and the issue goes away. Happens with any MSTP devices. I have a guy in my office that's brilliant with the Jace, he tells me it's because the Jace MSTP Driver is just not all that it could be. 4 trunks into a Jace - OK, but how many controllers on each?
PS - the BCM is not obsolete. They are still available, and will be for a while. They are pretty robust; I can't think of a reason to replace them until you discover a feature you have to have that they don't do.
~40/trunk off the top of my head. I'll have to check exact counts but I know I have multiple sites with more than 120 MSTP devices on a Jace. Granted without setting up tuning polices correctly this is a epic fail. But it works for us and is still plenty responsive. I would not hesitate to add plenty more to a J7 over Bacnet/IP.
Originally Posted by JohnLoves2ski
I have no control logic in these, only data logs, alarms, and graphics. Still far more than any CC router is going to touch.
I would ask how your tuning policies and polling rates are setup? COV?
We tend to pull a lot of data for building optimization. I think the issues start when we pass 65 on a trunk.
The CC router CAN handle it. And they are not necessary unless you have issues with an overloaded small Jace. With the larger Jaces, you would simply split the trunk. It's not a preferred engineered solution; it's a quick fix if you accidentally put to many MSTP devices on a trunk.