Step 7 sin function

barryoc · Oct 14, 2012

Hi everyone,

I'm having an issue with sin in step7. I tested the code in plcsim and it works fine. When i download it to the actual cpu it doesn't. I'm thinking it's something to do with an old cpu (315-2ag10). Attached is a screen shot of the code. As soon as it reaches sin it returns 7f800000.

Any help greatly appreciated.

Regards,
Barry.

KalleOlsen · Oct 14, 2012

I didn't recalculate your numbers in float, but could it be that the input value is much, much, much greater than PI? Or very close to 0? Could you change the view from hex to float?

Kalle

barryoc · Oct 14, 2012

Kalle,

Many thanks. I think its indicating an error.

Barry

L D[AR2P#0.0] · Oct 14, 2012

Similar results with a 317
Given that the SIN algorithm keeps subtracting (2*pi) from the number until it is less than (2*pi), very large floating point numbers will eventually run out of resolution and fail.
Check the CC codes after the SIN

L D[AR2P#0.0] · Oct 14, 2012

Overflow has occurred:

barryoc · Oct 14, 2012

Thanks LD

Mine shows 0_1011_0010

Regards,
Barry

Step 7 sin function

barryoc

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barryoc

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L D[AR2P#0.0]

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L D[AR2P#0.0]

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barryoc

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