User`s manual

BD2-3880/3890 User’s Manual
15
7.2 Explanation of Input/Output Signals
(1) RXD
Serial receiving data signal. On occurrence of framing error, overrun error, or parity error, the
data is printed as “?”.
(2) DTR
When this signal is READY, write data or a command. When they are written in BUSY, overrun
error is occurred and data is ignored. Data can be written into the input buffer even when the
printer is busy printing. A BUSY also occurs when the printer is powered on, in test print, in
Online mode, or being reset.
(3) TXD
If data remaining in the printer’s input buffer is 256 bytes or less, the printer transfers a DC3
(13H: Data Receive Not Ready) signal to the host. If data in the input buffer exceeds 256 bytes,
the printer transfers a DC1 (11H: Data Receive Ready) signal to the host.
(4) GND
Common GND on the circuit.
7.3 Error Detection
Parity, framing, and overrun are detected. On detection of any error, the data are stored in the
buffer as “?”.
(1) Framing Error
With “space” state having been detected on detection of a stop bit, error takes place.
The data are stored in the buffer as “?”.
(2) Parity Error
With an error having been detected under specifying parity check, the data is stored in the buffer
as “?”.
(3) Overrun Error
On detection of an overrun error, the data are stored in the buffer as “?”.