MusicalComa

Derived FB Calculation

4 posts in this topic

Hello Everyone, 

I am working with an existing project trying to improve the system. I have a Derviced FB Type called NAI_CALC and I cannot seem to reproduce the calculation correctly. The input variable is named UVT and based on live PLC data the value is about 74. The output variable is named NAI and based on live PLC data the value is about 6800. When I do the calculation by hand I am getting about 3700000000. I have included the actual calculation screenshot below. Is there a way to see the output of each calculation block in realtime to confirm my calculations by hand?

1.PNG

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Posted (edited)

Use a watch table of each blocks OUT value?

Another quick thing to check and or verify is the order of processing of the blocks.  The little number to the top left of each block is it's order of processing within the network.  Are the calculations in the correct mathematical order of operations?

Edited by pcmccartney1

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When you mention the watch tables, do you mean the animation table? I tried using an animation table but because the function blocks outputs are not variables I cannot include them in the animation table. The order of operations is correct.

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Then tie the outputs of each block to a new variable and then use the watch table.

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