Printronix P5000LJ Series - Manual (Page 273)

RS-232 And RS-422 Serial Interface Protocol
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Data Carrier Detect (DCD). Status signal to the printer. The ON condition is
required for the printer to receive data.
Data Terminal Ready (DTR). Control signal from the printer. Subject to
configuration.
RS-422
+RD, -RD. Serial data stream differentially received by printer.
+TD, -TD. Differentially driven serial data stream for transmitting status and
control information to the host. Subject to protocol selection.
RS-232 And RS-422 Serial Interface Protocol
X-ON/X-OFF. The printer transmits an X-ON character (hex 11) when
entering the Online mode or when the buffer is almost empty. The printer
transmits an X-OFF character (hex 13) when entering the Offline mode or
when the buffer is almost full.
RS-232 And RS-422 Serial Interface Error Handling
Parity Error Handling. Parity error checking is a configuration option
selected from the operator panel.
With odd or even parity checking selected, a character with a parity error is
replaced with a question mark (?) character.
When parity checking is not selected (“NONE” on the operator panel), parity
errors are ignored and the characters are printed as received.
Framing Error Handling. Framing error checking is always in effect for the
serial interface.
When a framing error occurs, an exclamation point (!) is printed. If 20
successive errors are received, a line feed is added to force printing to occur.
Overrun Error Handling. Overrun error checking is always in effect for the
serial interface.
When a data overrun error occurs, an asterisk (*) is printed. If 20 successive
errors are received, a line feed is added to force printing to occur.
Note ±RD and ±TD form signal and return paths of a differential line signal.
Note All serial errors are treated as faults that require operator intervention.