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Re: Mar. fun run
You can not "y" or combine to outputs into one input unless the
port is Rs-485 instead of RS-232. $85 is an un-balance data
15Volt +,- but has tri-state output drivers that will not load "pull low/
high" the line unless actually talking. at reset these outputs are
effectively open. In 232 the output is held low or high, so when one
is talking (alternating between +15volt & -15volt) and the same wire
is being held high (+15volt) when the talking one goes low (-15volt)
this puts a 30 volt direct short on the line overloading the output
driver chips. They are designed to handle short term (seconds
duration) shorts but a long term short (more than a min.) is not
advisable. There are data Mixers (I can make you one) available to
do this. Black Box Corp. is a good source if a home made one is
not an option. As far as trapping the data there are a few single
board processer systems (2" x2") that use eeprom programming to
run that could be programmed to look for a "data stream match" &
when it occurs to execute a specific action... such as close or
open a relay. It could also be set to look for a second data set to
"reset this relay" One board I have worked with that would be good
for this is "New Micros" out of Dallas Tx. It uses "Forth"
programming language. (I know of it but have not programmed in it
yet). This board runs off a single +12 volt dc supply & costs
around $120. We do our own eepron burning This with a home
brewed Data mixer might be your answer.... It could also be
programmed to Translate the data stream linking the 2 systems
together. This way everything would be done in the respective data
receivers/decoders/drivers ie. TIU, Powermaster, IC Track
controller.
Just a thought..
Randall
On 26 Mar 03, at 15:06, Ira Schneider wrote:
> Steve,
>
> It is more complicated than that.
>
> The TIU output still has to be connected to the Command Base so the
> MTH controller can send the appropriate commands to TMCC engines.
>
> I was wondering if we could connect the TIU output line to both the
> Command Base input line and the Command Base output line, this echoing
> all TIU originated signals to both the Command Base and the TPCs.
> However, I don't like the idea of two RS-232 transmitters connected in
> parallel to the TPC RS-232 receivers. As you said, there might be
> data collisions, but worse, it might overload the transmitters or
> receivers.
>
> The ultimate solution may be something I have been thinking about. I
> would like to design a box that monitors the RS-232 traffic out of the
> Command Base looking specifically for the HALT command. When it
> detects the Halt command it would energize a relay (or set of relays)
> that cuts power to all tracks, independent of the PowerMasters and
> TPCs. That way, we could have some tracks whose power bypasses the
> TIU altogether (like track 1 does now) but that will still shut down
> when the Halt command is sent. Also, we could have one or more tracks
> controlled strictly by the TIU without going through a TPC.
> Obviously, this design wouldn't work correctly since we now know that
> the Command Base doesn't echo the Halt command sent to it via the
> RS-232 port. However, we could theoretically monitor both the RS-232
> send and receive lines for the Halt command, catching both the
> commands from the TIU and the commands from the Command Base.
>
> The major problem is that I have not figured out how to design this
> box at all. I think about it now and again. Maybe someday I will get
> an inspiration and come up with a circuit that should work.
>
> In the mean time, what we have now works better than we had before.
> The only exposure we have now is that the E-Stop command from the MTH
> controller won't shut down power on track 1. We can live with that for
> now.
>
> By the way, I sent a message to Lionel tech support describing the
> problem and they were of absolutely no help. I haven't heard from MTH
> tech support yet.
>
>
> Ira
>
>
> ------
> TTAT members reflector.