CBM-230/231User ’sManual
23 CITIZEN
7.3.2 Data Configuration
(1) (2) (3)
(1) Startbit
(2) Data bit(+ parity bit)
(3) Stopbit( 1 or more)
(1) Startbit
Whenhalf a bit has passed since a fall edge of a mark to a space, the state ofthe bit is read in again, and if it
is a space, it will be recognized as a start bit. If it is a mark, it will not be recognized as the start bit. The
start bit will be detec ted again without assuming it to be an error.
(2) Data bit + parity bit
The data bit and paritybit are sampled for one bit worth of time since thetime of half the start bit and
assume the then state to be the data for the relevantbits. The bits are arranged in order of bit 0, bit 1, ....,
paritybit, startingfrom the one next to the start bit.
(3) Stopbit
The stop bit is a 1-bit or more mark level. If a space is detected in detecting the stop bit, a framing error will
result.
7.3.3 Error Detection
A parityerror, framing error, and overrunerror are detected. When an error is detected,that data is stored in the
bufferas "?."
(1) Framingerror
Whena spaceis detected at stop bit detectiontime, an error result. That data is stored in the buffer as "?."