Printronix P5000LJ Series - Manual (Page 120)

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Chapter 4 Host Interface Menu
Interface Type
Allows you to select either the RS-232 (the default) or RS-422 serial port
interface.
Data Protocol
You can 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 turning the transmission on and off.
In some situations, such as when the buffer is full or the timing of signals
is too slow or too fast, the printer will tell the host to stop transmission by
sending an XOFF character.
An XOFF character is sent when the number of empty bytes in the buffer
is less than or equal to 25 percent of the buffer size.
If the host keeps sending data after an XOFF is sent, the printer firmware
will continue to send an XOFF for every 16 characters received.
When cleared, the printer will resume receiving data (XON). The data
does not have any End of Text codes; XON / XOFF is a non-block
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 the ETX, thereby acknowledging 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. Data Terminal Ready. The printer controls the data flow by sending
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.
Baud Rate
Sets the baud rate of the serial interface in the printer. Baud rate is the speed
at which serial data is transferred between the host computer and the printer.
The choices for the RS-232 and RS-422 interfaces are 600, 1200, 2400,
4800, 9600, 19200, and 38400. The default is 9600 baud.
Note If you select a baud rate that is 19200 or greater, you may need to increase
the Buffer Size in K parameter from the default (1 Kbyte) to improve
performance.