Digital Equipment LGplus Series, Setup Manual

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4–39
The serial submenu allows you to choose either the Serial RS–232 or the
Serial RS–422 host interface type, as shown in Figure 4–14. Several other
serial parameters are included on this menu, as shown below and described
in the following pages.
Interface Type
This parameter allows you to select either the RS–232 or RS–422 serial port
interface.
Data Protocol
You may select one of the following serial interface protocols to meet the
host interface requirements.
•
XON / XOFF (the default) – The printer controls the flow of
communication from the host by telling the host to turn the transmission
on and off. This is the factory default serial protocol.
•
ETX / ACK – End of Text / Acknowledge. The host controls the flow of
communication to the printer by sending a block of data and ending the
block with an End of Text (ETX) signal. When the printer receives the
ETX signal, it will acknowledge it has received the entire block of data.
•
ACK / NAK – ACK means acknowledge; the device acknowledges it
has accepted a transmission. NAK means a negative acknowledge; the
device did not receive the transmission.
•
DTR – (DTE Ready). The printer controls the data flow by asserting or
de–asserting this hardware signal to the host. If there is enough room in the
printer buffer, the printer will send a high signal; if the buffer is full the
printer will send a low signal. DTR tells the host if it is safe to send more
data. (If the host sends data during an unsafe condition, data will be lost.)