Citizen Systems iDP3420, iDP3421, iDP3423 10.3 Input and Output Signals 10.3.1 Inputand Output Signals

iDP3420/3421/3423 User’sMa nual
33 CITIZEN
10.3 Input and Output Signals
10.3.1 Inputand Output Signals
(1) RXD
Thisis a serial received data signal. When a framing error, overrunerror, or parity error occurs, that
data is printedas "?".
(2) DTR
When this signal is Ready, write the data or a command. Ifwritten at the time of Busy, an overrun
error results, ignoring the previous data. The data can be written in the input buffer even during
printing. Busyis a lso issuedat thetime of power -on, test print, on-line, and reset.
(3) TXD
As data is received, the remaining capacity of the printe r’s input buffer decreases.
Whenit becomesless than 128(10) bytes, a DC3(13H)(Data reception disa ble signal) is outputt o the
host computer. On the other hand, when the remaining capacity of the input buffer increases to
256(20) or more bytes, a DC1(11H)(Data reception enable signal) is output to the host computer.
XON (11H) is sen t every 3 seconds in the Sta r mode.
When a command is recei ved, that requests the pri nter state and printer sta tus, 1-byte correspon ding
data is output.
Note: Thevaluesin()areforwhenthe256bytesoftheinputb uffer is selected by
DIPswitches.
(4) DSR
When this signal is a space, the data is sent from the printer side. Note that if this signal is a mark
when a request to send command is executed, the print er will wait until the signal b ecomes a space.
(5) FAULT
1CBM mode
Whenthis signal is Space,a mechanical error has occurred .
2Star mode
Whenthis signal is Mark,a mechanical error has occurred.
(6) RESET
Asignal to reset theentire printer. (Negative logic)