SATO D508 Service Manual page 32

THE RECEIVE BUFFER (CONT'D)
Multi Job Buffer
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.
When you are using the RS232 Serial interface, the Multi Job Buffer uses either the Ready/Busy
with DTR (pin 20) or X-On/X-Off flow control protocols. With an empty receiving buffer, the status
of DTR is "high" (or an X-On status if using X-On/X-Off), meaning the printer is ready to receive
data. When the receive buffer is holding 1.95MB of data (1MB from being full), DTR will go "low"
(or an X-Off is sent) indicating the printer can no longer receive data. This condition is called
"Buffer Near Full."
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 1MB bytes
of data are being held (1.95MB bytes from being full). At this time, DTR will go "high" or an X-On
is sent to tell the host that it can again receive data.
All printer error conditions (i.e., label out, Time-out Error, etc) will cause the printer to go busy
(DTR "low" or X-Off) until the problem is corrected and the printer is placed on-line. The printer
will also be busy if taken off-line from the front panel.
Page 2-8 D508/D512 Service Manual