problem in rs232 commnication


I’m working on simple application using X24-091 RF modules to set up rs232 between PC and a device.

It operates only simplex mode which means data from a module to the other is OK but NG in reverse direction.
I changed and tested modules but the same result.

Anybody gives me some help.
Why does this happen and how can I resolve it?

Did you check the DL/DH of the module not transmitting? Has it been set to the destination modules’ 64-bit address?