When I have a Master which to need to communicate with many slaves through the RXD,TXD pins, is it possible for the slaves to communicate with master independently. That is whenever the slave wants to do so. The reason why I asked is if there is an attempt by more than one slave to communicate with the Master at the same time, won't it cause a conflict? If so, how such situations to be handled?
Yes, if multiple slaves try to communicate at the same time, there will be conflict.
Therefore, you need to apply some kind of Protocol to ensure that this can't happen.
One way is for the master to poll each slave...
Is it not possible that when any slave communicate with master, it starts with a start byte and end with a stop byte which all slaves connected to the line will also receive.This information can be used by slaves to know whether the line is busy.
Yes - that would be your "protocol".
IF the slaves listen while they transmit, and you have a suitable design of the "start byte", you can use this for collision detection...
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