Square root in AC800M HI, FB RealIn2oo3

We had planned to use the standard block "RealIn2oo3" (BurnerLib) for our flow signals.

But it seams that the RealIn2oo3 does not have a paramter for square root. This is suprising as dP flow measurement is fairly normal.

Inputs are RealIO and FB "sqrt" is for real only.

AI880 cards does not have a square root option as NonSafe card AI810 has.

Any suggestions for how to solve this without changing the instrument configuration?

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Mr Control   

asked 3 months ago




Without to be sure if I understood correctly your question (I don't have RealIn2oo3 block either HI to see) why you don't try using of transfer trough real value:

- transfer the output of 2oo3 block (if it is RealIO) to real (out_real:=RealIn2oo3Out.Value)

- use out_real for square root FB

- the output of square root FB transfer again in RealIO if needed (RealIO.Value:=sqr_out)


answered 3 months ago


By Mr Control on 1/16/2018 | Like (0) | Report

thank you for your commment. I'm always sceptical when people have made their own blocks for a SIL application. in my opinion approved standard blocks should be used, specially blocks that connects to field equipment. in this case the customer has accepted to change settings in the instruments.

By kstoilov on 1/16/2018 | Like (0) | Report

Yes, that was only suggestion - that's why I wrote 'without to be sure'. Of course, if you can do that externally from the controller is easier. Standard blocks are locked, of course

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AI880A module of AC 800M HI does not support Sqrt of inputs.

It would be better to implement this on field instrument itself!!

Else you need to develop user defined SIL object to convert RealIO to RealIO by adding Square root for the value.

We cannot square root output (AverageInputValue, HighestInpiutValue or LowestInputValue) of the RealIn2oo3 object. If you do so the calculations on RealIn2oo3 object will go wrong.

I believe implementing square root on instrument would be better option than creating user defined SIL object to convert RealIO to RealIO.


answered 3 months ago


By Mr Control on 1/16/2018 | Like (0) | Report

thank you for your answer. this is same as my opinion, the customer will change the settings in the instruments. i'm just surprised that sqrt is not part of the block often used for flow. crazy

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