Service manual

Page 3-3

Section 3. Interface Specifications

PN 9001080

Rev. A

SATO M-8485Se Standard Print Engine

Service Manual

3.3 The Receive Buffer

The M-8485Se printer has 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 2.95MB.

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" ot maximize the performance

of the host and the printer.

When 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. See these sections

for more details. 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 2.0MB 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"

*DTR High

X-On

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 (2.0MB 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.

2.0 MB 2.95MB

Buffer Near Full

DTR Low

X-Off