x-Lab Dot Matrix Printer XDP-321 User's Manual
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Serial pin assignments
The following table lists the serial connector pin assignments and describes their respective interface
signals.
Pin No.
Signal
Direction
Description
1
Protective Ground (FG)
—
Printer’s chassis ground
2
Transmitted Data (TXD/SD)
Out
Printer has transmitted serial data
3
Received Data (RXD/RD)
In
Printer has received serial data
7
Signal Ground (SG)
—
Return path for data control signals
20
Data Terminal Ready (DTR)
Out
Positive when the printer is ready to receive data,
and negative when the printer is not ready
Figure A.2.3 Serial interface connector pin numbers