8.2.2.2
Plug Assignment
PIN Signal
Signal
Input/Output
Meaning
1 --- - free
2
R x d
I
Received data
3
T x d
O
Transmitted data
4
DTR
O
Data Terminal Ready
5 GND
- Signal
Ground
6 --- - free
7 RTS
O +12V
8
CTS
I
Clear to Send
9 --- - free
Pin 2
Received Data
(RxD):
Serial transfer of data from the computer to the printer.
Pin 3
Transmitted Data
(TxD):
Serial transfer of data from the printer to the computer system or the terminal (e.g.
XON/XOFF symbol).
Pin 4
Data Terminal Ready
(DTR):
Printer output, which allows the transfer of data to the printer or which interrupts it
(handshaking). Data transfer is possible, when DTR is high. It is not possible, when
DTR is low.
Pin 5
Signal Ground
(GND):
The reference potential for the entire data exchange.
Pin 7
Request to Send
(RTS):
This signal is always high with a switched on printer.
Pin 8
Clear to Send
(CTS):
Input of the printer, which allows the transfer of data to the computer or which in-
terrupts it. When the input is high, then the printer may transmit the data. For the
software handshaking with Xon/Xoff, this input must always be high.
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