I have include a modified pic from the Legacy User manual that shows how I think the attachment between Arduino, Legacy Base, and a Lionel SER2 is accomplished. Would like to know if this is correct.
Second, I believe in this interconnection, the Tx of the Arduino and SER2 are connected together, then to the Rx of the Base. So if this correct, does the Base "echo" a serial command from Arduino to SER2? i.e.. does the Base receive the serial command from Arduino, then retransmit out so the SER2 would see the command. Example, I have DZ2500 switch machines connected to the SER2. I want to send a switch command from Arduino to DZ2500 via SER2. This would require Base to receive then retransmit switch command.
Hi MED -
The illustration you posted depicts the use of the Legacy Y-cable, which allows the TMCC command base to send serial commands into the Legacy base. I take it you're proposing to connect an Arduino instead of the TMCC Command Base to the Y-cable.
If you have a SER2 on the Legacy PDI bus, then yes I think the Legacy Command Base should echo serial commands received from the "Command Base" end of the Y-cable on the PDI bus. So if you have a DZ-2001 plugged into the SER2, your DZ-2500 switches should get the Arduino commands. You would need the Y-cable along with the Legacy DB9 cable connected as shown on p. 9 of the SER2 manual.
I think the Y-cable is receive only from the "Command Base" end, so you would not be able to receive serial commands from the Legacy base with the Arduino in that configuration.
However, if you already have a SER2 connected, you might be able connect the Arduino to the screw terminals on your SER2 if they are free. Because the DZ-2001 only uses the serial output and not the serial input it might work, even though the manual says you can't use the INP screw terminal if something is connected to the SER2 DB9 port.
My configuration is like this:
SER2 --- DZ-2001 --- MTH TIU
SER2 --- Arduino (via screw terminals)
The switches receive commands from the Arduino because the SER2 passes the commands down the Legacy PDI bus.