flotulopex, A simple oper collector transistor for each PIC output. These would be tied togeather to the bus. The master would have a resistor tied to VCC to source current to the bus. Each PIC would also have this bus line as an input. Then before the remotes transmit they would check to see if the bus is active (low) before they transmit there data. This bus structure is used in vehicles and one of the physical layer types is ISO-9141.
The standard baudrate for ISO-9141 is 9600.
Dave Purola,
N8NTA