Question on use of Legacy serial port for TMCC commands

One follow-up question: The TMCC appendix says, "The first byte is OFE, followed by two bytes corresponding to the 16-bit words of the command table."  What does OFE mean, and what should those first 8 bits be? Thanks for any help...

   Bob A.

 To answer the first question. I think so. There are a couple of windows programs out there that claim to send TMCC commands to a Legacy base through the serial port as well as through the TMCC base.

 The OFE is a hexadecimal number actually 0FE (zero FE). I believe it is equal to 254 in decimal form. So the first 8 bits should be 11111110. I have been wanting to fiddle with the same thing on a Windows laptop but can't seem to find the time.

Ron

Bob, I have emailed you an article that appeared years ago in the TTOS Bulletin.  It covers the basics of the TMCC word structure.  I have used it to write test code for exercising devices.

I do not think you can send commands to the Legacy base.  I thought you could only send commands to the TMCC base.  I thought I had heard Lionel set up the Legacy base to ignore all incoming commands.  Bob, if you have a TMCC base, try it on that one and see if it works.

I've never heard that you can't send commands to the Legacy base, and that would seem to be somewhat short-sighted of Lionel to have done that.

I agree. I think that the base must accept incoming commands and review them, as otherwise you wouldn't be able to program the black modules. That depends upon the base receiving commands via the serial cable and then acting upon them.

The Legacy Base certainly accepts commands from the TMCC Base, but the pins are a bit scrambled in that "Y" cable.  The output of the TMCC Base Pin 2 goes into Pin 4 on the Legacy Base, and the Legacy Base output on Pin 1 feeds the TMCC Base input terminal on Pin 3.

There are 4 separate serial I/O channels on the Legacy 9-pin.  Pin 5 is the common ground for all 4 pairs.

I wonder what all those channels are used for?

One for TMCC Base

One for Serial output to controllers & accessories

Two unknown, but Jon Z's comments about coming smart accessories leads me to believe they will use the unused ports to avoid disturbing the status quo.

Dale,

Is it that it won't accept Legacy commands then?  I remember reading or hearing that commands coming in are ignored.  Maybe I heard it wrong and it will accept tmcc commands.

Dale...  Is there a link to the article?  If not would you please send me a copy?  I'd sure appreciate it.

Of course it accepts TMCC commands!  The TMCC Base easily talks to the Legacy Base over the "Y" cable.

Here's Lionel's Complete Guide to Command Control , in the back you'll find the specifications for the command protocol through the serial port.  Since the TMCC command base talks to the Legacy and it understands it, one would have to assume that it talks the same language.  Obviously, the Legacy command base knows about additional commands for Legacy specific functions, I don't know if they're documented at this time.

The Legacy commands are a 9bit command instead of an 8bit. That's why a TMCC engine won't respond to a Legacy command when Legacy is set up on a TMCC engine in the Legacy base. The commands aren't documented and aren't in the public domain. And I doubt they ever will be.

Ron

Hey Dale, how about emailing me that article.

Ron

I'd like to get that one as well.