Actually, we can see this example in the project semi-automatically created with TRNSYS 3D. Type 15(Weather data) has a variable named "AA_H_0_0" on parameter field and it is defined in an "equation". So I thought it is easy thing.
But I tried this in generic types, for example Parameters#2(pipe length) of type31(pipe), and the simulation would stop with error saying the parameter is invalid.
Thanks in advance.