Why does the sender router's message appear on XBEE_RX instead on XBEE_TX

I am testing XBEE3 with the mesh kit. Everything works in terms of sending and receiving messages, except for some confusion over two physical pinouts, XBEE_TX (DOUT/DI013) and XBEE_RX (DIN/CONFIG/DI04).

When a sender router sends out an UART message wirelessly, I expect to probe the same message (with my digital oscilloscope) on the sender router’s XBEE_TX (DOUT/DI013). Strangely the message wasn’t probed on TX but Instead is capture on the XBEE_RX (DIN/CONFIG/DI04). How could a sender’s message appear on the RX pin?

I’m not sure if there is an error in the documentation or perhaps a bug in the firmware.

You have the lines backwards. DOut is data Out of the XBee via the UART to your processor where by DIN is data In from your processor into the XBee modules to be sent over the air.

I think you may have misunderstood my question. Here I’m using a router xBee (router-A) to emulate a sensor or processor that creates the UART message and delivers through wire to another router xBee (router-B), which in turns sends the message wireless to the coordinator. I was supposed to wired router-A’s DOUT to router-B’s DIN, but it didn’t work that way. Only when I shorted router-A’s DIN to router-B’s DIN did router-B received the message and sent to coordinator!

That is not what I would expect to work. Shorting DIn to DOut is what I would have expected to work. That would be Pin 2 to pin 3.