Compaq PrintNet 5525B, User Manual

Page: 117 / 238

Serial Submenu
117
Interface Type
This parameter allows you to select either the RS-232 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 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 negative acknowledge;
the device did not receive the transmission.
•
DTR. 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.) DTR
is not available when RS-422 is selected.