...LB - as long as your back.. I'd like a fix on the 1004 with JACK. Right now, I don't know JACK completely, but would like this corrected before I take the time to learn JACK, otherwise what I do know won't mean JACK.
I take it, Ed, that because you don't know the answer, it is time to move on. But, let's close this trivia exercise. Actually your first answer of 255 is the maximum number of subnets on a channel however it depends on the media being used.
A Subnet is a logical description of usually a single channel and can include up to 127 devices. But, you could have multiple subnets on a single channel if you had a bunch of physical layer repeaters for twisted pair media or if the media was powerline, fiberoptics, or something else that supported hundreds or thousands of devices on a single segment.
BTW, you cannot assign the subnets - LNS does it for you!
Sysint...you may want to copy/give him that email string I posted the other day. Pay close attention to the second entry, the one that states BACnet isn't really interoperable. No names, but it was written by a BACnet testing engineer.
I think you're referring to the Domain ID which can be manually defined or LonMaker can randomly create one - which LM does by default. Only LNS can hand out the subnet ID's (unless you hack into it with Nodutil). Plus, you wouldn't want to manually assign it as that would increase the probability of having duplicate subnet/node address' among control devices which could result in unpredictable control behavior. Like turning on the chiller and the boiler at the same time!
Back to my post regarding subnets on a channel, I wanted to point out that bad things can happen by using a lot of PLR's (physical layer repeaters) to build large networks. PLR's repeat everything, even noise. Better to install a backbone and use LPR's (configured routers). Routers only forward valid packets and can also function as repeaters if needed.
Awhile back, I talked to some maintenance guys from a large casino where the controls contractor installed 300 devices on one channel using PLR's. Response time and performance was ugly until the maintenance guys themselves replaced the PLR's with LPR's and showed the controls contractor the door. Now, they manage their control network themselves.