Error Handling - Epson SQ-2550 User Manual

Signal level
Mark (1)
Space (0)
Handshaking
Handshaking by DTR signal or X-on/X-off. The DTR signal
changes to mark - meaning the printer is not ready to receive
data - when the number of bytes free in the input buffer drops
to 256. The signal changes to space - meaning that the printer is
now ready - when the number of bytes in the input buffer rises
to 512.

Error handling

A * character is printed if a parity error is detected.
All other errors are ignored.
Connector
D-SUB 25-pin connector
In the table below, the direction of signals is given relative to
the printer.
Pin Signal
number
2 TXD
20 DIR
3
RXD
7 SG
1
FG
Other pins are not used.
8-14 Technical Specifications
3V to 27V
+3V to +27V
Signal
direction
Transmits data for X-on/X-off
out
out Whether or not the printer is ready to
receive data
in Receives data
-
Signal ground level
-
Printer chassis ground
Description