Documentation

Printing with Zebra GK420d

Connect Zebra GK420d printers, install drivers, and validate label outputs.

Hardware setup

Unbox the GK420d and remove all packing materials. Connect the power supply and USB cable (or Ethernet for network printing). Load label media: open the cover, place the roll on the spindle, feed labels under the guides and through the printhead. Close the cover and press the Feed button to calibrate. The printer will feed several labels and stop when ready. Status light should be solid green. If flashing, check media loading or run calibration again.

Driver installation

**Windows**: Download Zebra Setup Utilities from zebra.com/support. Run the installer and select GK420d. Connect via USB and the driver will install automatically. For network printers, add using IP address. **Mac**: Download CUPS drivers from Zebra. Add printer via System Preferences > Printers. Select 'Zebra GK420d' as the model. **Linux**: Use cups-lpd package and ZPL driver. Set the printer as default for the workstation. Test with a Windows test print or `lpr -P PrinterName testfile.zpl` on Mac/Linux.

LollipopWMS printer configuration

In LollipopWMS, go to Settings > Hardware > Printers. Click 'Add Printer.' Enter a name (e.g., 'Shipping Station 1 Label Printer'). Select type: Thermal Label (ZPL). For connection: choose 'Local (USB)' for direct connection or 'Network' and enter IP:port. Set default label size (4x6 for shipping, 2x1 for barcodes). Assign to a workstation or make available warehouse-wide. Save and print a test label to verify configuration.

Label template setup

LollipopWMS includes default templates for common labels: **Shipping (4x6)**: carrier-compliant format with barcode, address, and routing. **Product barcode (2x1)**: SKU, description, and barcode. **Location tag (2x1)**: location code with scannable barcode. **Pallet label (4x6)**: SSCC barcode with contents summary. Customize templates from Settings > Labels > Templates. Use the visual editor or upload custom ZPL. Test print each template after changes. Keep a library of approved templates for consistency.

Troubleshooting print issues

**Blank labels**: Printhead may be dirty—clean with isopropyl alcohol swab. Check that media type matches settings (direct thermal vs thermal transfer). **Faded print**: Increase darkness in printer settings (Zebra Setup Utilities > Configure Printer Settings). **Labels skipping**: Run media calibration—hold Feed button for 3 seconds until it blinks, then release. **Paper jams**: Check for label debris under printhead. Ensure media is properly seated. **Not printing**: Verify printer is online, connection type matches configuration, and print queue isn't paused. Check LollipopWMS printer logs for errors.

Device setup

Zebra GK420d — Printing Labels

Follow this guide to connect desktop thermal printers and keep shipping labels consistent shift after shift.

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Overview

The Zebra GK420d handles 4x6 and 4x8 labels with ease when paired with LollipopWMS. This guide covers USB and network setups, default media settings, and template tips.

Connect it with carrier integrations such as UPS to confirm label compliance before peak days.

Prerequisites

LollipopWMS workstation with driver access.
USB-B cable or Ethernet adapter with static IP.
Latest Zebra Setup Utilities or OS-level drivers.
Sample label from the pack and ship workflow for testing.

Step-by-step (USB/Network)

USB install

Connect the printer via USB-B and power it on.
Install Zebra Setup Utilities, choose GK420d, and set media to direct thermal.
Print a test label from LollipopWMS; confirm darkness and speed settings.

Network install

Attach Ethernet and hold the feed button until the network config label prints.
Assign the printer a static IP in the same subnet as the workstation.
Add the printer in LollipopWMS using the IP and port 9100, then print a live batch label.

Common ZPL snippets

Use these starters to adjust layout without rebuilding templates.

^XA
^PW812
^LL1219
^FO40,40^A0N,60,60^FDOrder: ^FS
^FO40,120^BY2,2,90^BCN,120,Y,N,N
^FD${ORDER_NUMBER}^FS
^FO40,280^A0N,40,40^FDShip To:^FS
^FO40,340^FD${SHIP_TO_NAME}^FS
^XZ

^XA
^FX Additional reference text line
^FO40,420^A0N,30,30^FDPick Wave: ${BATCH_ID}^FS
^FO40,470^A0N,30,30^FDSku Count: ${SKU_COUNT}^FS
^XZ

Troubleshooting

Blank labels usually mean media type is set to thermal transfer; switch to direct thermal.
Streaking indicates worn printheads; clean with isopropyl wipes and recalibrate.
Skipped labels resolve by holding feed for two flashes to run an auto-calibration.

FAQs

How do we reset the printer?

Power off, hold the feed button, power on, and release after four flashes to restore defaults.

Can we print PDFs?

Yes. Use Zebra Designer to convert PDFs or send raw PDFs through the Windows driver when ZPL is not required.

What darkness setting works best?

Start at 15 for standard thermal stock. Adjust in increments of two to balance clarity and printhead life.

Keep labels sharp all season

Combine tuned printers with LollipopWMS automations to support every carrier SLA.