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Can equations reference a table to calculate a computed channel?

Can equations reference a table to calculate a computed channel? If not, is this in the plan?

I recall talk of a SDK at sometime, is that in the plan still?

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There is currently not built in formula support.  However, additional information about what kinds of calculations the you are trying to perform with this method could be helpful.

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In the built in calculated channel you can't currently reference a table.  Starting in 2019 R4 (the most recent version) you can create a calculated channel plugin in LabVIEW using the plugin development kit (http://www.ni.com/pdf/manuals/378088b.html). There is a new example project (Rosette calculation) and template project (Create Calculation) that would be good starting points.  Adding built in support for table type calculations is also something we are interested in.  Any details you have around exactly what you are trying to do with the formula will help us ensure we make something that will address your use-case.

Kevin Fort
Principal Software Engineer
National Instruments
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Yes, I am aware of the SDK.  Just haven't had time myself to explore it.  Generally we post process our calculations in Excel after testing.  This is generally a time consuming part and have these calculations on the fly would speed up our testing process.

A few examples of what we would use table type calculations are the following.

1.  Relative humidity, dry bulb / wet bulb calculations.

https://www.engineeringtoolbox.com/humidity-measurement-d_561.html


2.  Super heat and Subcooling calculations for refrigerants.

We use multiple refrigerants in our products. So a nice feature would be able to store/load/switch between tables/Gases in calculations.  A calculation manager (like in Diadem) to save calculations so they don't have to be retyped and possibly retyped incorrectly resulting in errors would be nifty.  The tables listed below are three refrigerants that we currently use in our systems.  2  (r404a, 134a) out of the 3 have equations that have been compiled from their associated tables by the manufacture. While the other (R449A) we depend on the Vlookup function in Excel to aid in our calculations using the provided table after testing is complete. The ability to have these calculations on the fly would allow us to shorten our testing time.  The two gasses (134a, r404a) that do have equations to model their tables, I believe I can get to work in Flexlogger currently. But these two gasses are being phased out and I haven't had to work with them recently. Being able to load their tables would remove the error asscioted in their equations, but it would be marginal.

 

Table links below:
Thermodynamic Properties of Opteon™ XP40 (R-449A) SI Units

https://www.chemours.com/Refrigerants/en_US/products/Opteon/Stationary_Refrigeration/assets/download...

 

Thermodynamic Properties of Dupont Suva (R-404A) SI Units

https://www.chemours.com/Refrigerants/en_US/assets/downloads/h49744_Suva404A_thermo_prop_eng.pdf

 

Thermodynamic Properties of  (HFC-134A) SI Units

https://www.chemours.com/Refrigerants/en_US/assets/downloads/h47752_hfc134a_thermo_prop_si.pdf

 

One other request/feature I would like to see is power measurement being incorporated into Flexlogger via the high voltage/current c series modules. I would love to be able to get entry level power analyzer measurements from my Cdaq in flexlogger.

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