[TRNSYS-users] changing value only under certain conditions

[Liam O'Brien]

Cramer,

Try inserting an equation.  Create an output variable called "signal" or something.  This variable will take on the value 1 for when the window is allowed to be opened; 0 for when it is not.  Then, make signal equal to "and(ge(mod(time,24),8),le(mod(time,24),21))".  Basically, this is saying: if the time is greater than or equal to 8 AND less than or equal to 21, then output the value 1, otherwise it takes on zero.  If the type you're using uses an input that is a control signal, then this equation can be directly linked to it.  I confirmed that the equation works by connecting the equation to an online plotter.  Hope that helps. 

Liam O'Brien

Date: Fri, 12 Sep 2008 19:01:55 +0200
From: silkworth at transsolar.com
To: trnsys-users at engr.wisc.edu
Subject: [TRNSYS-users] changing value only under certain conditions








Hi 
All,
 
I'm trying to model 
manually-operated windows, ie that can only be opened or closed when 
someone is around to do it. Thus, I need a way to modify a variable only at 
certain times - for example, so I can change my airchange rate 
accroding to outdoor temp **only if** hr>8 and hr<21. I know of type 
93 (input value recall), but can't think of how this helps. I also know about 
chaining GT(), LT(), etc, to form logical operations, but everything I can think 
of would assign a new value at each timestep. I need more of a real 
if(condition)-then(action), but I know these don't exist in trnsys. Any 
thoughts?
 
Thanks,
Cramer
 

J. Cramer 
Silkworth
Transsolar Climate 
Engineering
Technical consulting for energy 
efficiency and environmental quality in buildings.
145 Hudson 
Street
Suite 402
New York, NY 10013
Office: 212-219-2255
Mobile: 347-283-2547
silkworth at transsolar.com
 

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