User guide

Printer Communication Interfaces
A.4 Automatic Port Selection
• As long as there is data in the printer’s input buffer, the currently active
port remains active.
• If the input buffer of the active port remains empty for 2 seconds, the port
is disabled by placing it in the standby state. At this time the other port is
enabled.
• When the parallel port has just been put into the standby state, the serial
port is enabled as follows:
– XON is sent by the printer, if XON/XOFF control is enabled (or XON
/XOFF + DTR for the LA600 printer).
– The DTR signal is set high by the printer.
– If DEC PPL2 protocol is selected, the Answerback message (when auto-
answerback is enabled in setup) and then the power-up initialization
message (when enabled in setup) are sent.
• When the serial port has just been put into the standby state, the parallel
port is enabled as follows:
– An ACKNLG (pin 10) pulse is sent by the printer.
– BUSY (pin 11) is set low.
– SLCT (pin 13) is set high.
Note
Please note the following:
• The Data Set Ready (DSR) signal from the serial port is not
monitored for the purpose of automatic port selection.
• During self-tests (including the automatic power-up test) and when
the printer is in setup mode, both ports are disabled.
• The Answerback function is not supported by the LA75 Plus
printer.
• In the LA310 MultiPrinter, the Answerback and power-up
initialization messages (when enabled) are sent when the serial
port becomes active, not when it enters the standby state.
• When the Answerback function is used with the LA600
MultiPrinter, set the interface communications to the serial
port.
A–6 Printer Communication Interfaces