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Data Synchronization
After the printer receives a Lock Request from the host, the printer will respond. (See Print Status
Response section for details.) The host (Host-A) will be granted a lock only if the printer is not printing.
Once the lock is granted, the Host-A will begin to send the print data for the current print job with the
<ESC s> command. (See “Print Job Structure” section above for additional details). If another host
(Host-B) requests the printer’s status, the printer will respond that it is printing. No other host can
interrupt the print job of Host-A.
The data goes into a buffer and the printer sorts through the various commands applying the print job
settings.
The data between the height value in the <ESC D> command and before <ESC G> or <ESC E> is the data
that will be printed, also referred to as print data.
Label Positioning
A motor-driven platen, which acts as a pinch roller, controls label movement within the printer. The
control electronics track label travelling positions. An infrared LED photocell detects the top-of-form
sense hole that is located between labels. The absolute positions of the label and the tear bar are
calculated based up the reading of an infrared LED photocell sensor.
Top-of-Form Sync
At power up, label position is always assumed to be correct. If an Out of Paper condition is detected at
power up, user requires to press form feed button and the stepper motor will advance until label load to
Top-of-Form tear bar position.
Label Length
The label length is determined by the SKU data found on the NFC Tag.
If the roll has continuous form paper the Form Feed command (<esc> E) is changed to feed enough dot
lines to allow for the last line of print data to extend past the printer tear-bar.
The host can use <esc> L to Set Length to Continuous Stock. See more details in the “Printer Commands”
section later in this document. Only authentic Dymo labels with a valid NFC Tag can be used for printing.
Label-Movement Commands
There are two label-movement commands implemented in the LabelWriter 550 Series: Form Feed, Short
Form Feed. These commands operate as follows.
Form Feed Command (<esc> E)
This command advances the most recently printed label to a position where it can be torn off. This
positioning places the next label beyond the starting print position. Therefore, a reverse-feed will be
automatically invoked when printing the next label. Use Feed to Print Head (Short Form Feed) to
optimize print speed and to eliminate the reverse feeding when printing multiple labels.
