I have an Arduino Uno and I'm having trouble having getting two serial devices to communicate (the one being the Uno, and the other being a Bluetooth module).
Each of the devices can communicate with itself just fine (if you wire the TX to the RX). A byte sent is a byte received. simple. It works that way for both devices. Each can loop the serial connection back to itself just fine.
The Uno is running at the same baud as the BT module (according to the module's specs), but even if they weren't the same baud, at least some data would be sent (although it would be misinterpreted/jumbled, something would be received). Because, right now, no data is being sent back and and forth. Nothing. Nada.
I feel that the problem is a Ground because it seems no signals are being sent along the TX/RX lines. I have tried connecting the module to a different Ground on the Uno. But certainly it is grounded to the same thing as the Arduino. They are both being powered by the same power source and therefore, would share a ground.