iDP-3420/3421/3423 User’s Manual

10.3Input and Output Signals 10.3.1 Input and Output Signals

(1)RXD

This is a serial received data signal. When a framing error, overrun error, or parity error occurs, that data is printed as "?".

(2)DTR

When this signal is Ready, write the data or a command. If written 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. Busy is also issued at the time of power-on, test print, on-line, and reset.

(3)TXD

XON (11H) or XOFF (13H) is sent at XON/XOFF control. XON (11H) is sent every 3 seconds in the STAR mode.

When a command is received, that requests the printer state and printer status, 1-byte corresponding data is output.

(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 printer will wait until the signal becomes a space.

(5)FAULT

1CBM mode

When this signal is Space, a mechanical error has occurred.

2STAR mode

When this signal is Mark, a mechanical error has occurred.

(6)RESET

A signal to reset the entire printer. (Negative logic)

(7)RTS

This signal is turned to Space when the printer is turned on.

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Citizen Systems iDP-3420, iDP-3421, iDP-3423 user manual Input and Output Signals 10.3.1 Input and Output Signals