1. How ensure that both transmitter not sensing data at time. If this thing happen then data collision occur.
2. For such multi device u need Modbus protocol for communication. Because if ur receiver never identify who sending what data.
3. U required to sense bus is busy. if use Master Slave concept then each time master send request to slave 1...slave 128 status. For each
slave response if it match it's ID & then respond wit data.
4. For this ur Enable signal require to be controlled according to Tx-Rx data condition