Direct thermal 6 ips and a movable black mark sensor
The GX420d is a 4-inch desktop printer that prints 203 dpi direct thermal labels up to 6 ips (152.4 mm/s), with no ribbon mechanism. The top speed of its 300 dpi sibling, the GX430d, is 4 ips.
With the factory option movable black mark sensor installed, it reads black marks or notches on the back of the media even when they are off center. Align the arrow on the sensor cover with the right edge of the mark, and since notches at the media edge are easily damaged by side-to-side wander, keep the sensor as far from the edge as possible.
Gap detection works wherever the sensor arrow is within the alignment key range. If the arrow is outside the alignment key range, it reads only black marks and notches and cannot detect label gaps or continuous media, so return the arrow within the alignment key range when going back to gap labels.
The same gap sensor position as the LP/TLP 2844
The GX420d's default gap detection position is slightly right of center. It is offset so that even 2-across labels, with 2 labels side by side in one row on the roll, read the gap of one row.
| Sensor position | Zebra models that used the same position |
|---|---|
| Default (right of center) | G-Series fixed sensor, LP/TLP 2842, LP/TLP 2844, LP/TLP 2042 |
| Center aligned | LP/TLP 2742 |
Cut width 19-108 mm on the cutter option
The factory-installed cutter cuts label liner and thin tags 19-108 mm wide, and cut lengths shorter than 25.4 mm risk cutter jams or errors. Blade life is 2 million cuts on 10-120 g/m² media and 1 million cuts on 120-180 g/m² media.
The cutter makes a cleaning cut on its own once every 25 cuts; this function can be turned off with the cutter.clean_cutter command, but leave it on. Putting tools, cotton swabs, or alcohol inside the cutter risks blade damage and jams, and there are no user-serviceable parts inside the cutter.
3 network options and the parallel port
A GX420d without options has 3 ports: USB, serial, and parallel. When one of wired Ethernet, Wi-Fi (802.11b/g, with LCD), or Bluetooth (with LCD) is installed at the factory, that network is added to USB and serial and the parallel port is removed.
The successor ZD621d, with no parallel port
GX420d sales ended on December 31, 2021 (Asia-Pacific) and January 31, 2022 (other regions), and Zebra customer support closed on February 28 and April 30, 2025 respectively. The designated successor, the ZD621d, prints 203 dpi up to 8 ips with Ethernet, serial, and USB standard and no parallel port, so PCs connected by parallel cable change their wiring to USB or LAN. Drivers are on the GX420d download page.
