V2.1.11 and Serial Module

Hi there - I’ve set up two TBeam1.1 boards in a network and I have a 1200 baud device that occasionally sends short data strings. It is meant to send from one board to the other and then into a computer (sort of virtual RS232 cable). My setup command is:
meshtastic --port COM18 --set serial.mode SIMPLE --set serial.txd 14 --set serial.rxd 13 --set serial.enabled true --set serial.baud BAUD_1200
My phone is attached to the receiver TBeam and when the serial device transmits, I can see the SERIAL_APP Packet in the Debug Panel of the receiver TBeam. However, the data is not output onto pin 14 (I’ve attached a scope probe to that pin and it stays consistently at 3.3V).
Any suggestions on how to make it transfer the received data onto the serial transmit pin?
It is my understanding that there is no addressing involved, i.e. I’m not specifying anywhere that it should be a specific TBeam to capture the data and output it onto the serial transmit line.
Thanks for any clues.