iDP3420/3421/3423 User ’s Manual
10.3Input and Output Signals
10.3.1Input 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
(3)TXD
As data is received, the remaining capacity of the printer’s input buffer decreases.
When it becomes less than 128(10) bytes, a DC3(13H)(Data reception disable signal) is output to 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 sent every 3 seconds in the Star mode.
When a command is received, that requests the printer state and printer status,
Note: The values in ( ) are for when the 256 bytes of the input buffer is selected by DIP switches.
(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)
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