Niagara N4 BQL Expr Component

[intech]

ExprLogic

New to N4/Niagara but was wanting to use an ExprLogic to look at OAT and see if it's between two numbers then trigger a Boolean output
Can that be done?

[orion242]

ExprLogic

New to N4/Niagara but was wanting to use an ExprLogic to look at OAT and see if it's between two numbers then trigger a Boolean output
Can that be done?

Sure could do that, see the help doc for the expression syntax.

Or just use the tstat block and call it day as it does exactly that.

kitcontrol - HVAC - Tstat

[numbawunfela]

If I am not mistaken the Tstat block splits the differential, so a 70 deg stpt and 2 deg differential makes it throw at 69 and 71. Confusing for the end user. It doesn't apply the differential to the tail end of the process like everyone expects it to, throwing at 70 on the way up and throwing again at 68 on the way down for example.

[orion242]

Or you add a complicated but standard add/sub block and make it work exactly as you like.

Surf the docs with help - search exp block. Its in there. Support is going to be a hassle with that over the standard blocks if everyone that touches it needs to refer to the manual vs 15sec of testing. Maybe ones sure all their techs are familiar with exp blocks. Surly that covered in the three day crash course....

This line of thinking also leads to program objects to do the same function as standard blocks. Real time saver now that they need to be signed.

[y7turbo]

Probably just use 3 blocks, a greater than, less than , and block.

The greater than will be the low point of your range , the less than will be the high point. If the OA is between the greater and less block settings, they will both be true, the And block will go true.

[orion242]

Could skin this cat in a ton of ways with the standard blocks. Its trivial logic.

Its Niagara, there are a 1K hard paths and <3 easy ones in the end. Custom blocks for something this simple, needless support nightmare.

[y7turbo]

Could skin this cat in a ton of ways with the standard blocks. Its trivial logic.

Its Niagara, there are a 1K hard paths and <3 easy ones in the end. Custom blocks for this, nightmare in the end.

No doubt, a million ways to do every task.

[orion242]

Confusing for the end user. It doesn't apply the differential

Agreed. Sub/add 0.5 the diff to the setpoint linked into the tstat and now its what most expect. Setpoint & deadband also eliminates swapping the on/off setpoints.

Still the standard blocks for something this simple is something one can look at a wiresheet for a few seconds and understand whats going on. Use all program and expression blocks like some do, the station can quickly become something you just want to nuke and start over vs support.

[numbawunfela]

I always put text blocks in the worksheets. It is good for the other guys, but so for me. I am a good figure-out-er and a bad rember-er. It takes the edge off of a station that makes you want to blow your brains out.... unless I want to spite somebody, then they are easily removed.... hehe

[Right Control]

Yep like stated tstat setpoint is center of the differential. Is annoying but easily worked around with several of the options mentioned. I use the the AX community ones if I want above or below triggers. I also use a lot of text blocks in my wire sheets for notes. I don't have the recall I once did, so does help the aging brain.