Thanks AArdvark.
I had read Ralf's Train pages. Helped a lot but not completely. (Cant see how he gets his Xor checksums though) It is exactly the "Sniffing" of the Cab Bus that Ralf talks about that I am trying to do. When (say) F5 is pressed, record the number of the loco associated with that Cab, and go from there to set up the storage entry/exit and drive the loco in/out, control the lift an so on. Not that hard when one charts it out, but I am snagged on how to recognise the "Control this loco" command(s) from Cab to CMD.
I have ground my way to the understanding that the Cabs really are dumb and that all data is stored in the Command Controller - a PowerPro in my case - as you say. But the issue I have is that the NCE doc's specify all dumb terminals respond to a Ping with two byte response - Key Press and Speed, and cannot change their response type. Though that does not quite correspond with Ralf - he has fice and two byt resonses in his discussion. No mention of what the Cab06 sends in response to a Ping after Enter is pressed. But that response must be at least three bytes - Enter (0x60? and two address bytes.
I got an answer from NCE on this today and it was about the five byte response the CMD box sends to Cabs:
"Q How does the PowerPro learn what loco number the Cab 06 is controlling?
A The cab receives an 0xdb multibyte from the command station after entering a loco or
when just ENTER is pressed during normal operations."
I have rephrased the question, and will let you know what answer I get.
Their reply does not explain how the data gets to the CMD station in the first place. I suspect the response is 0x60 followed by three, or maybe the standard five bytes, CMD being alerted to a non-two byte response by the 0x60. I guess I am just going to have to put my logic analyser to work and do a few tests to find out.
I will let you know how it goes. A relatively simple thing I would have thought made difficult by confusing and incomplete documentation from NCE. But in true Quixote fashion I am determined to smash this windmill.
Quixote.
PS on your traverser,
Suggestion. Use decent size steppers to make a bird of the job, and drive them with Gecko drivers. Your controller than needs to supply a direction signal and the pulses. The Gecko's microstep, turning (say) a standard 200 steps/rev motor into a 1000 step per rev one. Good resolution is need as the top of the rails are only 1mm wide, giving not much margin for misalignment and derailments.
As to the Grand Plan, there are five of us working two afternoons and one evening for the last five years. Two ex Army WOI's, One truckie, and Mr Weller (Used to run the soldering equipment part of Weller Australia - he gets all the difficult soldering jobs. Me? Army, Concrete Industry, Appliances and Automotive in various positions. Our in joke over out coffee sessions is the trains will never run (They have) and the opening ribbon will be cut at my wake.