And in the latter, each slave interface is connected to the same master and no lines between slaves. In the former system every interface shares the same signal line, which makes a parallel structure system (Parallel type). One of them is a system that every interface can become a master occasionally (no more than one can be a master), and the other is that a master is already predetermined and the others can not become masters at all. There are two kinds of systems in the master-slave structures.
#SERIAL COMMUNICATION TYPES SERIAL#
And the serial data are transferred only between the master and one of the slaves, never between a slave and a different slave. So only one of them works as a master to conduct others, slaves, which obey the master’s instructions. If there are no conductors and every interface operates individually, the system becomes chaos easily. Those interfaces share the same lines to communicate each other. The importance of the distinguishing Master from Slave is in the system where many serial interfaces are existing. (Master and Slave relation is different from Transmitter and Receiver relation.) The conductor is called a master, and the others, slaves. There must be at least two relevant players, a transmitter and a receiver, in the serial communication system. Unless comprehending the data format, serial interface network can never be constructed. Like this example, when a transmitter transfers string data with ignoring the data format, the receiver can not receive the data correctly. And if the railway company ignore the sequence and prepare trains with arbitrary sequence of cars, the morning commuting passengers at the railway stations will get into a panic. Even though the sequence of the cars is determined by a railway company, the passengers also understand the car sequence, and at the railway station, they will wait for the train at the position where the car they wants to ride on will stop. Each train is a combination of those cars and there will be a definite rule of the sequence of cars.įor example, the car for train operator cannot be in the middle of the train, or dining car cannot be at the end of the train. Please consider a train as another example.Ī train consists of a car for train operator, cars for ordinary passengers, priority cars ( like women car ), dining cars, special cars with special fee, and so on.
#SERIAL COMMUNICATION TYPES CODE#
Each code and the transfer data must be positioned correctly according to a data format. As in this example, a data format is a rule to specify the position of each data and code in the sequence of a transmitted data. One example of the sequences is like that at the beginning a start code is followed by an address of the transmitter, an address of the receiver, transfer data, an error detection code, and a stop code at the end, which shows that the transfer data is surrounded by the special function codes. Serial communication has, usually, a regulation of its data sequence. The asynchronous communication system has better noise immunity but receiver’s circuits would be more complicated. 16 times is sometimes used.)Īnd it is common that a start bit ‘0’ is added before a set of transfer data, and a stop bit ‘1’, after the data, in order to comprehend when the content of the data is transferred.ĭata transfer without clock signal lines is called asynchronous transfer. In this case, 1bit data (1 or 0) is supposed to be valid when the same data is caught three-times continuously or four by the receive clock (‘4 time higher’ is just an example. The receive clock has a higher frequency, for example, 4 time higher, than the transmit clock. (2) To clarify the start and stop timings when a set of data is transferred. (1) To catch receive data by using higher frequency clock than transmit clock. The combination of the followings is one solution. So there must be some way to get the timing even without the clock signal. This may disable the communication even though the noise problems are eliminated. One of the side effects is that the receiver can not understand the timing when it should catch the data.