Hmm... Looking at your files is seems that it is just an ACK from the boards. I don't see anything standing out that would indicate a color change. It's just the same data over and over again.

In your log, when you say something like "red". Does that comment appear before or after you've switched to red?

Another thing I noticed... If you look at the schematics, they show the board addresses. They look to correspond to the board numbers: 5, 6, and 7 with one having dip switches for setting the address.

One thing that you might want to try is unplugging all but one of the boards in the 485 chain and see how your data changes. That would determine if it is in fact an ACK that you are receiving. (Also try it without any boards plugged in.)

I also don't know why, but I have a hunch that 0x3d 0xdf 0xfd might be an end of transmission signal. Reminds me of the good old 0xDEAD 0xBEEF 0xFEED

I wonder if you could just ask Stern for the protocol? Maybe they would give it out?

Anyway cool thread. I'll try to help out if I can.

Upon a little closer inspection...

It looks like "board 8" contains unused inputs. I'm going to guess that unplugging this board will help you get better data. Maybe the CPU is querying this board and getting back FF's for all of those inputs.

Looking at the manual, it's RS-232 out from the CPU that goes into a bridging microcontroller (AVR) out to RS-485. The RS-485 bus/network contains 4 ARM controllers that are addressable. These ARMs drive the 74HC595s. So, I'm guessing that there would be some kind of addressed command sent out along with a byte where each bit is an output state to the 74HC595s.

Sounds like it should be pretty simple to see, but the data shows other wise.

Could you unplug all boards except for the CPU and see what's being sent out? That should eliminate any extra "noise" in the data.