In my project , I am using one AT89s8252 and one DS89c430 microcontroller. These two are connected serially. CAN controller is connected to AT89s8252 & RF receiver is connected to DS89c430. Data are exchanged by serial communication. It is possible that at a same time both MCUs may want to transmit to other. My project doesn't want data loss. If both the MCUs load the data to SBUF to transmit to other at a time then who will be the receiver first without loosing its own data. Plz help me......

 

As far as I know your UARTS in both processors are full duplex. This means they can both transmit at the same time. You do have to connect them correctly however, that is TX to RX and RX to TX and GND to GND -- Right?

You can avoid losing any data by using the RX interrupt and having a circular queue on both receivers of some appropriate depth.