Trouble getting variable handle in PythonPlugin

asked 2020-11-28 16:03:55 -0500

Mehrdad Vojdani
1125 ●4 ●12 https://www.linkedin.c...

updated 2020-12-08 22:43:03 -0500

I'm having trouble getting some variable handles using PythonPlugin in energyplus. I wonder if all the variables listed in the *.rdd output file are available for the python plugin ...

For example here is what I got in the *.rdd file:

Output:Variable,prm,Plant Supply Side Cooling Demand Rate,hourly; !- HVAC Average []

and here is what I used in my python script to get the handle:

self.sensors["demand rate"] = self.e.get_variable_handle(
              state, "Plant Supply Side Cooling Demand Rate", "prm")

Unfortunately, the API returns -1 value for this variable and some other variables. I can't figure out what's the problem. It seems that all the variables listed in the *.rdd file cannot be handled by PythonPlugin. If I'm right, how can one identify available variables(sensors) for each model? I hope that you can help me with this.

P.S.

self.e = self.api.exchange

answered 2020-12-01 05:38:49 -0500

Red
78 ●4

The get_variable_handle method of the Data Transfer API takes 3 input parameters:

state, variable_name , and variable_key.

You should first request the variable to be available for access during simulations, by adding an Output:Variable to your input file. Then you can find the variable_name, and variable_key to your desired variable from the output.eso file.

In your case, the variable_key you provided seems incorrect.