Handshake (flow control) When sending and receiving data between devices, data may be lost when data is sent when the receiving side is not in the receiving state, so it is important in communication to check the other side's state.The handshake (flow control) is a function that maintains the reliability of communications. Parity check details On the sending side, a parity bit of "1" or "0" is added to the data so as to make the number of "1" data bits even for EVEN and odd for ODD.On the receiving side, the number of "1" data bits is counted and the data is judged as being correct if the number is even when EVEN and odd when ODD. Parity check setting This is a function to find errors in the data and is selected from "even parity check (EVEN)", "odd parity check (ODD)", or "no parity check (NONE)".
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Data bit length This specifies how many bits each item of data is composed from.This depends on the device being used, but normally specify 7 bits for alphanumeric characters and symbols, and specify 8 bits for 1 byte binary data.
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Stop bit length This sets the length of the bit that indicates the end of the data.This is normally selected as 1 bit, 1.5 bits, or 2 bits.The start bit length is fixed as 1 bit so this setting is not necessary. Transmission rate Specifies the number of bits to send each second.The unit is bps (bits per second) and is selected from 300, 600, 1200, 2400, 4800, 9600, 19200, and so on.By matching the settings and timing, the data delimiters correspond, and data can be normally sent and received.For this reason, a start bit is added to each item of data (1 byte) to acquire the correct timing. In asynchronous communication, data is sent and received one bit at a time on one data line, so if each side's communication condition settings do not initially match, normal communication is not possible.Matching the computer (controller) side settings to the peripheral equipment side settings is the normal setup method. Asynchronous communication This method sends and receives data synchronized to each side's own self-generated clock.Normal communication is not possible if the transmission rate settings do not match.In other words, both the sending side and the receiving side initially agree on how many bits to transfer each second, and then each creates a synchronization signal of a frequency that matches that transmission rate. Synchronous communication This method sends and receives data synchronized to a clock generated by the other equipment or by a self-generated clock.Communication is performed is based on a synchronization signal added to each bit from the sending side.This has good data transmission efficiency but there is a demerit in that the transmission procedure becomes complicated.
#SERIAL COMMUNICATION TYPES SERIAL#
In serial communication, data is sent one bit at a time using one signal line, so in order for the receiving side to accurately receive the data, the sending side must know at what speed it is sending each bit.In RS-232C, synchronous communication and asynchronous communication standards have been defined.For peripheral equipment used for measurements or control, the previously mentioned full-duplex communication and asynchronous communication are typically used. Asynchronous communication and synchronous communication Half-duplex communication A method where communication is performed using one transmission line while switching between send and receive.For this reason, simultaneous communication cannot be performed. Half-duplex communication and full-duplex communication Full-duplex communication A method where send and receive both have their own transmission line so data can be simultaneously sent and received.
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