MATLAB REAL-TIME WORKSHOP 7 - TARGET LANGUAGE COMPILER Bedienungsanleitung Seite 334

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8 Serial Port I/O
8-14
eighth bit is used, it must have a value of 0. If the data is based on the extended
ASCII character set, then eight bits must be used since there are 2
8
or 256
distinct characters.
The Parity Bit
The parity bit provides simple error (parity) checking for the transmitted data.
The types of parity checking are given below.
Mark and space parity checking are seldom used since they offer minimal error
detection. You may choose to not use parity checking at all.
The parity checking process follows these steps:
1 The transmitting device sets the parity bit to 0 or to 1 depending on the data
bit values and the type of parity checking selected.
2 The receiving device checks if the parity bit is consistent with the
transmitted data. If it is, then the data bits are accepted. If it is not, then an
error is returned.
Note Parity checking can detect only 1-bit errors. Multiple-bit errors can
appear as valid data.
For example, suppose the data bits 01110001 are transmitted to your
computer. If even parity is selected, then the parity bit is set to 0 by the
Table 8-2: Parity Types
Parity Type Description
Even The data bits plus the parity bit result in an even number
of 1’s.
Mark The parity bit is always 1.
Odd The data bits plus the parity bit result in an odd number
of 1’s.
Space The parity bit is always 0.
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