CBM America CBM-720 - Manual (Page 34)

CBM-710/720/730/750 User’s Manual
28 CITIZEN
(2) Data Composition
[1] Start bit
[2] Data bits (and parity bit)
[3] Stop bit (1 bit or more)
[1] Start bit
1/2 bit past the line dropping from MARK to SPACE, a status reading is taken again. If the reading is SPACE,
a start bit is recognized, but if it is MARK, it is not taken as a start bit. This is not regarded as an error, but the
search for the start bit is performed once again.
[2] Data bit and Parity bit
Data bits and parity bits are the data of the bits in question, which are represented by the state at the times
sampling is performed. This is accomplished at time intervals equal to one bit in length, beginning from the
middle of the start bit. The order of the bits is, starting with the bit closest to the start bit, bit -0, bit-1 ....., pa rity
bit. (Note: data bits are based on "one point sampling".)
[3] Stop bit
The stop bit consists of one or more bits at "mark" level. When "space" level is detected for a stop bit, a framing
error occurs.
(3) Error Detection
Parity, framing and overrun errors can be detected by your printer. When an error is detected, the ALARM
lamp goes on, the buzzer is sounded, the related data is abandoned, and the printer shifts to the next incoming data.
The ALARM lamp can be turned off by pressing the LINE switc h.
[1] Framing error
When "space" state is detected during stop bit sampling, the ALARM lamp goes on, the buzzer sounds, and the
related data is ignored.
[2] Parity error
When parity check is designated, and if when checked an error is detected, the ALARM lamp goes on, the
buzzer sounds and the related data is ignored.
[3] Overrun error
When an overrun error is detected, the ALARM lamp goes on, the buzzer sounds and the related data is ignored.