Digital Equipment LGplus Series, Руководство по установке

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5–17
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.
NOTE: +RD and +TD form signal and return paths of a differential line
signal.
RS–232 and RS–422 Serial Interface Protocol
X–ON/X–OFF — The printer transmits an X–ON character (hex 11) when
entering the Ready mode or when the buffer is almost empty. The printer
transmits an X–OFF character (hex 13) when entering the Not Ready mode
or when the buffer is almost full.
RS–232 and RS–422 Serial Interface Error Handling
NOTE: All serial errors are treated as faults that require operator
intervention.
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.