Data Structure; Dtr Mode - Star Micronics SP300 Series Programmer's Manual

2-6. Data Structure

2-6-1. DTR mode

This mode is accessed when the DIP switch 3-5 is ON.
Signals are controlled using the DTR line as BUSY flag.
RXD
DTR
Printing
RXD
DTR
Printing
PAPER OUT signal
If a printer errors do not occur after the power is turned on, the DTR signal line
changes to "SPACE".
When the host computer confirms that the DTR signal line is set to "SPACE", the
host computer sends the data text via the RXD signal line to the printer. Also, the
printer will set the DTR signal line to "MARK" when the empty space in the data
buffer is below 256 bytes. After the host computer detects that the DTR signal line
is at "MARK", transmission of the data text is sopped. In this instance, data can
still be received up until the data buffer becomes completely full.
When the empty space in the data buffer is increased following printing (when the
data in the data buffer is reduced to 256 bytes or less), the printer sets the DTR
signal line to "SPACE".
Data
Buffer full
Power ON
When paper is out
Power ON
Data
Buffer empty
OFF LINE
Paper out
– 14 –
Data
ON LINE
Press the ON LINE switch after
loading paper.