CRC-16-DNP Calculation Trouble

[14gipper]

Having trouble implementing a Labview version of a CRC calculation performed in our FW. This is for a 16 bit DNP protocol. I have implemented a very simple VI that I believe is true to the code implementation, but I am not coming up with the same results.

Test message is

05 64 0b c4 01 00 40 00

with a proper CRC of 

A72E

I however get a CRC calculation of D158. Not sure where I have gone wrong. Any help would be greatly appreciated.

[crossrulz]

My only guess at the moment is that you make a mistake in the table.  I just do not have the time to check all 256 elements.

[pangvady · Accepted solution]

Looks like you might have missed one last step from the calculation. After googling CRC-DNP, the final step is to take the complement and swapping bytes to get the final answer.

[crossrulz]

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@pangvady wrote:

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Rube!  There is a primitive called Swap Bytes that you can use instead of the Separate Numbers and Join Numbers.

[14gipper]

That did it. Thanks for the catch. Banged my head against the monitor all day over that.

[14gipper]

Finished VI attached for the next lost soul searching for DNP CRC.