unit enumeration

[henningjp]

Description

There doesn't appear to be a way to get the unit enumerations from the DLL required to set the USER1 and USER2 Units through the High-Level API (i.e. REFPROPdll).

Documentation states (emphasis mine):

• UNITUSER, UNITUSER2: Set a predefined set of units based on the user’s need. Two different sets can be assigned depending on the input sent to the routine. The variable hIn contains the numbers that are specified by theenumerations in the CONSTS.INC file, separated by semicolons. For example, hIn=‘0;157;0;0;0;403;0;0;0;0’ would set the pressure to use units of atm and the speed of sound to use units of km/h. The numbers are listed in the order of T, P, D, H, S,W, I, E, K, and N (temperature, pressure, density, enthalpy, entropy, speed of sound, kinematic viscosity, viscosity, thermal conductivity, and surface tension). Because the enumerations might change, it is best to build this string with the enumerations listed in the CONSTS.INC file rather than hard coding the numbers as shown above.

However, the only way I can find to get these values is to dig into CONSTS.INC to get the unit code numbers and hard code them into my wrapper code. GETENUMdll does not return these enumerations.

Expected behavior: GETENUMdll (or some other public function) should return these enumerations.

Actual behavior: Unit values have to be hard coded into any wrapper code that calls the public functions from the REFPROP DLL.

Versions

REFPROP Version: 10.0.0.2
Operating System and Version: Windows 10 Access Method: C++ wrapper development

Additional Information

If possible, please post examples and/or screenshots of the issue.

[ianhbell]

What's the question?

[henningjp]

Sorry, hit return too soon. Issue updated.

[ianhbell]

I would say: don't use user-defined units. It's a Pandora's box best kept closed.

[henningjp]

Hmmm. OK. I'll work around it and take care of the unit conversions in the wrapper. I was trying to avoid that. It does work quite well, though! I get all the right answers in the USER2 units, which is just a slight variation from the MASS SI units. I just needed a way to future proof the wrapper code. I wanted the REFPROP10 calls to be dimensionally consistent with my Legacy API calls (where I handle the units in the wrapper code).

[ianhbell]

I am going to take a much more stripped down approach to units in REFPROP 11. I personally think that REFPROP should only support base SI units and let the user deal with unit conversions since there are already good libraries for dealing with units in many programming languages (though not Excel I admit).

[henningjp]

OK. Thanks.