Two small changes to be able to talk to a Johnson Controls NCE

[gnmerritt]

Docs for the device here: https://cgproducts.johnsoncontrols.com/met_pdf/1201531.pdf?ref=binfind.com/web

Explanations in the commit messages, needed both to be able to consistently talk to a (probably overloaded) controller device

[coveralls]

Coverage increased (+0.001%) to 46.267% when pulling 3b5eba0 on gnmerritt:johnson-controls-nce into 834cbd5 on ChristianTremblay:develop.

[ChristianTremblay]

Those seems like good catches. In what context does the application null property occurs ? Never saw that....

Regarding the formatting of debug, I was not aware of that... and was slowly converting eveythin to ".format" style until I decide to go for f-string. Do you know if the issue will be the same with f-string ?

[gnmerritt]

Yeah, so .format or f"{}" are both evaluated as part of the function call (and always happen even if the line isn't printed) - the syntax I switched to uses logging's built-in string formatting and so it's smart enough to skip the formatting if the logger isn't going to print. In my own apps I tend to split the difference by using f-strings for info/warn/error and trying to remember to use the special syntax for debug statements. I think it probably doesn't matter unless the things you're printing are properties that cause lots of network/disk IO.

For the application null thing: I saw it when trying to read Points.bacnet_properties for one of the points on the NCE. No idea how common the case is in the wild but I checked the packets out in tcpdump and the null case appears to be a well-formed bacnet message, so I figured this was the best way to handle it. The property had a datatype of bacpypes.basetypes.BinaryPV and here was the debug info I pulled:

pv=<bacpypes.constructeddata.Any object at 0x7fcaebc52760>, datatype=<class 'bacpypes.basetypes.BinaryPV'>
<bacpypes.primitivedata.Tag(null) instance at 0x7fcaebcbea00>, data=bytearray(b'')
                <bacpypes.primitivedata.Tag(null) instance at 0x7fcaebcbea00>
                    tagClass = 0 application
                    tagNumber = 0 null
                    tagLVT = 0
                    tagData = ''
 tagClass=0, appTagClass=0
 tagNum=0, enumAppTag=9