Citizen CBM-1000 User Manual page 34

4. Electrical Characteristics
4.1 In/output signals
(1) RD
When a framing error, overrun error or parity error occurs, the data containing
the error is printed as a "?".
(2) DSR
If the DTR/SDR control is selected, the host sends data to the printer after it
confirms that the DSR line is at space. If the XON/XOFF control is selected, the
host sends data to the printer by ignoring the DSR signal status.
(3) INIT
This signal can be used as a reset signal after switching the DIP switches.
When the pulse width of the signal is 1 ms or longer in space state, a reset will
be applied.
* Mark=logical "1" (–3 V to –12 V)
4.2 Data Configuration
Mark
Space
Data status is read again 1/2 bit time after the falling edge of mark to space
transition. If a space is detected, the data is recognized as a start bit. If a space is not
detected, the data is not recognized as a start bit, and attempt is made again to
detect a start bit.
The data is sampled 1 bit time after the start bit is detected.
Data bits are arranged in the order of bit 0, bit 1, bit 2, ...., and (stop bit), from the
start bit toward stop bit.
* Space=logical "0" (+3 V to +12 V)
b0, b1, b2 ...
(1) (2)
— vi —
t
(1) Start Bit
(2) Data Bit (+Parity Bit)
(3) Stop Bit
(3)