Citizen PPU-231 Manual De Usuario

PPU-231 User’s Manual

 

 33 

CITIZEN

 

t 

Mark 

b

0

, b

1

, b

2

, 

• • • • 

 

 

Space 

      (1) 

         (2) 

          (3) 

 

 

(1) Start Bit 

(2) Data Bit (+ Parity Bit) 

(3) Stop Bit (1 or More) 

(1) Start 

bit 

The system reads the status again after a lapse of 1/2 bit from a fall edge from the mark to space, and if it 

is a space, this bit will be recognized as the start bit. 

If it is a mark, the system will not recognize the bit as the start bit and try to detect the start bit again 

without judging it as an error. 

(2)  Data bits + Parity bit 

The system samples the data bits and parity bit for the 1 bit worth of time from 1/2 start bit and assumes 

the then status as the data for the relevant bits.    The bits are called Bit 0, Bit 1, ..., Parity bit, counting 

from the one closest to the start bit. 

(3) Stop 

bit 

The stop bit is the Mark level of 1 bit or more.    If a space is detected in detecting the stop bit, a framing 

error will result.   

The system detects a parity, framing, or overrun error.    If an error is detected, the relevant data will be 

stored in the buffer as "?". 

(1) Parity 

error 

With a parity check specified, if an error is detected at parity check time, the relevant data will be 

stored in the buffer as "?". 

(2) Framing 

error 

This error results if the Space status is detected at stop bit detection time.    The relevant data will be 

stored in the buffer as "?". 

(3) Overrun 

error 

If an overrun error is detected, the relevant data will be stored in the buffer as "?".