Specifications

28 DR300
3. Interface Specification Operation Manual
3.3 The Receive Buffer
The printers have the ability to receive a data stream from the host
in one of two ways. The receive buffer may be configured to accept
one print job at a time or multiple print jobs. The single job print
buffer is generally used by software programs that wish to maintain
control of the job print queue so that it can move a high priority job
in front of ones of lesser importance. The multiple job buffer, on the
other hand prints all jobs in the order they are received by the
printer, and the order of printing cannot be changed.
Single Job Buffer
The printer receives and prints one job at a time. Each job must
not exceed 34 K bytes. DIP Switch 2-5 (Off).
Multi Job Buffer DIP Switch 2-5 (On).
The printer is able to continuously receive print jobs, compiling and
printing other jobs at the same time. It acts much like a “print buffer”
to maximize the performance of the host and the printer. The Multi
Job Buffer mode is selected with DSW2-5. The Multi Job Buffer
uses either the Ready/Busy with DTR (pin 20) or X-On/X-Off flow
control protocols. See these sections for more details. With an
empty receiving buffer, the status of DTR is “high” (or an X-On sta-
tus if using X-On/X-Off), meaning the printer is ready to receive
data. When the receive buffer is holding 32K bytes of data (2K
bytes from being full), DTR will go “low” (or an X-Off is sent) indi-
cating the printer can no longer receive data. This condition is
called “Buffer Near Full”. See Figure 3-1.
The receiving buffer will not be able to receive more data again until
a “Buffer Available” condition occurs. This takes place when the
receiving buffer has emptied so that only 26K bytes of data are
being held (8K bytes from being full). At this time, DTR will go
DTR High or
X-On
Buffer Near Full
DTR Low or
X-Off
0
32K 34K
Fig. 3.1