AB on Ethernet - Open questions for you all.


Thread Starter

Ron Gage

Hi folks.

First of all, thanks for the warm response for my project. Your comments are really appreciated. This thing is only my second C programming project - being self taught.

I know there are a few of you out there that have NDA's with Allen Bradley regarding the Ethernet Protocol for the PLC5's and what not. Now, I realize that none of you can reveal the actual layout/structure of the header, but can any of you freely answer some questions about a couple of the bytes in the header (without revealing the actual functionality/structure). Specifically,
if you look at my code (i.e. getstatus.c), you will see the 4 bytes I refer to as 'header.b5' through 'header.b8'. Just how critical are the values of these bytes. I have noticed with my packet sniffer that these bytes periodically
change, especially when uploading from a PLC. Without violating your NDA's, can anyone give me any hints on what these specific bytes are doing?


Ron Gage - Saginaw, MI
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