Serial Data Buffer
Page 5
Operation
Upon the first receip t of data, the D ata Buffe r will initializ e a timer and beg in
storing data into its mem ory. It will no t begin sen ding the sto red data to the output
device until the buffer is full or when no data is received for five seconds,
whichever occurs first. When the Data Buffer begins outputting stored da ta, it will
flow control the host using the selected approach to prevent any new input. When
the buffer has been emptied, flow control with the host will be restored. Note that
for large print jobs that exceed the Data Buffer’s capacity, a timeout may occur in
the host that may appear as if the printer is off line. For this reason , it is
recommended that the un it be config ured to ac comm odate the largest frequ ently
occurring print job.
The Data Buffer will support simultaneous bi-directional serial communications at
the selected data rates. It was d esigned primarily , howev er, for app lications in
which 90% of the communications traffic flows in the forward direction (i.e. from
Input to Outpu t). Forwar d throug hput w ill slow dra matically with large am ounts
of reverse flow data (i.e. from Output to Input). The Data Buffer has the capability
of asserting flow control to the output device when the reverse flow buffer is fu ll.
Controls and Indicators
Reset Button
The Reset bu tton is used to reset the D ata Buffer to initialize memory, to re-read
the dipsw itches, to ena ble the co py featur e, or to initiate th e internal self- test.
Copy Button
The Copy button is used to automatically create multiple copies of a given print job
or to repeat the most recent job printed. To have the Data B uffer crea te multiple
copies, press the Reset button to clear all previous settings. Then, within 3 seconds
and before sending data, press the Copy button once for each copy desired. The
Data In LED will blink each time the Copy switch is pressed. After pressing the
Copy switch the desired number of times, the unit will then wait indefinitely for the
data stream to begin. Note that the internal copy counter is limited to 255. The
Data Buffer will begin outputting the specified number of copies five seconds after
receipt of data has stopped . The Da ta Buffer will not acc ept new data inpu t while
it is outputting data.
As an added convenience, the Copy button can also be used to repeat the last print
job. To create another copy of the latest job, simply press the Copy button after the
job is done but prior to the next job. Note that only that data contained in the
internal bu ffer will be o utput w hen this fea ture is used .
Data In/Out LED
s
The Data In L ED w ill flicker as data is being inp ut into the b uffer. The Data Out
LED will flicker w hen data is being sen t to the outp ut device .