I have two XTend modules. I have tested them using X-CTU, and all comms are good when performing the loop back range test. Both units transmit and receive.
When I hook them up to my equipment I get this:
Side 1: XTend unit has red light on to show power, and the green light above that is blinking to indicate it is receiving communication from my device. No yellow light, and all 3 green reception lights are out.
Side 2: XTend unit has red light on to show power, all 3 green reception lights are on, yellow light shows outbound communication to my device, but the green light that would show communication incoming from my device is off.
If I swap the two XTend units, I have identical results, side 1 is still transmitting, side 2 is still receiving, but no communication the other way, so it's not as if one of the radios can't transmit or receive, they both can do both.
If I hook up my two devices with just a straight serial cable, eliminating the XTend units, I have perfect communication.