Why do some of my RCM4200 cores act like the ethernet is crossed over?

This is a follow-up to my previous question regarding non-functional ethernet in new RCM4200 cores. (not sure that one’s going to be approved)

We found out the problem cores worked when plugged into an auto-crossover switch. Then we found out they worked when plugged into the Uplink port of a non-auto-crossover switch.

That makes it appear the the RCM4200 is crossed over. Is this a selectable option via hardware or software?

I’ve randomly had issues such as this over the years but never tracked it down until a bunch of my new Rabbits misfired.

If you’re using a beta of Dynamic C 10.72A, or the Open Source version on GitHub, it could be because of a bug in ASIX.LIB.

The version that shipped with DC 10.72 works fairly well, but a patch added to GitHub introduced a bug that affects how the ASIX Ethernet controller establishes link.

I pushed a fix up to GitHub last week, and it will be part of the official 10.72A release scheduled for this week.


I have been using the 10.72 code available (sort of, if you search long enough) on digi.com. I only found out about the github move last week. I’ll watch for the patch.

I now realize that I probably have been using auto-crossover hubs a lot of the time…and I nearly threw away a non-auto hub because it wouldn’t work with any of my Rabbits. I just now caught this work-around.