CRC: using different polynomials in GXworks 3

[Saxony Thermal 0]

Hello,

 

I tried following this post first but they go a different direction.
https://forums.mrplc.com/index.php?/topic/36694-how-to-calculate-crc-gx-works-3-fx5/

I want to do a CRC calculation and there is syntax for it already in ladder. But as the linked post says, it is defaulted to a CRC-16 polynomial.

I need CRC-CCITT. The manual describes as a precaution that there can be other polynomials and will produce different results... and CRC-CCITT is one of them listed.... Ok... can gxworks3 CRC generator do CRC-CCITT?

I do not see how I can instruct it to do that for me. The SM8562 needing to be off for 16bit, and on for 8bit makes me think theres some other SM object to adjust to get my CRC-CCITT?

 

Does anyone know?

 

Thanks!

[Saxony Thermal 0]

attached is the table i saw showing my polynomial of interest. And the path to it in e-manuals. You'll see in that page that it doesnt say how to produce those CRC's, just to be aware of them. There are far more than those polynomials for CRC so I wonder why even bother mentioning a specific few if it couldn't produce them?

Edited 2 May by Saxony Thermal

[Saxony Thermal 0]

Anyone have ideas? I have been putting off making a CRC check from scratch in the event we find out how to make this built in checker change polynomial but that time of "putting-off" is nearing an end (not the end of the world, just would save me a ton of time).

[Saxony Thermal 0]

I was able to get ahold of mitsubishi tech support and they read over the manual with me.

They assured me that there is no way to change its polynomial output and were even surprised that some CRC function existed at all.

Well, the time has come to make it from scratch in pure LD. Wish me luck. *jack hammer noises