IFI Controller Tether protocol

[bear24rw]

Here is the patent for the control system i found a long time ago when looking to it.

It details the checksums as DCH style checksums. I have no idea to this day what that means. I remember looking for hours and not understanding it :/

I even had an excel sheet full of dumps that i was trying to analyze lol

And yeah power can go over the line too but i dont think you have to worry about it. when i was sniffing the data i had a rs232 splitter plugged directly into my computer.

BTW i think that the dashboard protocol and tether protocol are identical. so you can use the dashboard port to try to figure out the checksums

definitely let me know if you figure them out id be really really curious

[Frank Neuperger]

Originally Posted by bear24rw

Here is the patent for the control system i found a long time ago when looking to it.

It details the checksums as DCH style checksums. I have no idea to this day what that means. I remember looking for hours and not understanding it :/

..........................................
definitely let me know if you figure them out id be really really curious

Terrific find that patent. It is the missing link. I did not know it existed.

I have a comms/DSP background and BCH stands for the last names of dynamic Trio of Raj Chandra Bose, Dwijendra Kumar Ray-Chaudhuri, and Alexis Hocquenghem. In the late 50's B and C discovered these codes and about a year later, H did the same or vice versa order of discovery. Now we need to figure out if IFI used one of the known BCH standards. Unfortuantely as I recall these work using syndrome generation though matrix operations and you can fiddle with the generator matrix or one of the vectors and result in an identical (strength ) code to the standard but with proprietary coding (scrambled syndromes) . I really hope that IFI did not get that sophisticated as it might be a real pain to reverse engineer the the proprietary scrambling. We also need to know what data fields of data each checksum operates on and the mapping of that data in the generation the checksums (syndromes per BCH). A good question is if with the 8 bit syndromes, any of the the BCH matrix operations can be reduced to table lookups in the interest of reducing computational effort. Also wondering if they are just using BCH syndromes for error checking or are they actually doing error corrections (FEC).

Besides the BCH, what concerns me as well is the "negotiation" that has to be done between OI and RC prior to the start of telemetry. The transaction diagrams are in the patent but no protocol is detailed for these.

We will play with it some more. Thanks again for the patent lead!!!!

[Frank Neuperger]

removed duplicate post