Before you start
- Have the printer, its power supply, label roll and the computer that will print. For a ZD621, identify the exact model and whether it uses direct thermal labels or thermal transfer labels with ribbon.
- Check the printer’s configuration report or Zebra Setup Utilities for its resolution. ZD621 printers use 203 or 300 DPI, depending on the installed printhead. Match that value in SlabOS; 600 DPI is not the ZD621 setting.
- Measure the actual label width across the roll and its height in the feed direction. Width must fit the printer’s printable area. A 4 × 6 inch roll means 4 inches wide and 6 inches long, not 6 inches wide.
- An owner or administrator configures shop printer profiles and sticker templates. Other users keep their existing inventory permissions.
1Connect and prepare the ZD621
Use the official ZD621 support page below for your model’s drivers and setup instructions. On Windows, install the Zebra driver before connecting USB. Power the printer, load the correct media and any required ribbon, and follow Zebra’s SmartCal instructions for that media.
Print the printer’s configuration report to confirm it feeds and prints correctly before opening SlabOS. For Ethernet or Wi-Fi, first configure the printer on the shop network using Zebra’s instructions for its installed connection option.
2Install Zebra Browser Print on the printing computer
Download Zebra Browser Print for your supported Windows or Mac computer from the official link below. Install and start it. In Browser Print, discover the ZD621 and set it as the default printer. That default is separate from the operating system’s default printer.
Open SlabOS on that same computer. Accept the SlabOS site in Browser Print when prompted. Keep Browser Print running. If your browser requests permission to access local devices or the local network for SlabOS, allow the connection for the site you are using.
SlabOS’s Zebra print option sends to Browser Print’s default device. Naming a SlabOS printer profile “ZD621” does not select a physical USB printer; set the default device in Browser Print as well.
3Create the SlabOS printer profile
Open Settings → Inventory → Inventory scanning & labels → Printers. Choose Add printer profile. Enter a recognizable Printer name, select System / Browser Print as the Connection, and select the printer’s actual Resolution: 203 or 300 DPI for a ZD621. Describe the loaded roll under Media profile / label stock.
For ordinary QR or barcode labels, leave RFID encoding off. If this should be the shop’s normal printer profile, choose it under Default printer. Click Save scanning & label settings. The profile stores SlabOS output settings; it does not install a driver or pair hardware.
4Match the sticker to the label roll
Open Sticker designer in the same settings panel. Choose the slab or rack template, set its width, height, units and margins, and arrange the fields, text and QR or barcode. Match its DPI to the intended printer, especially when printing without a separate profile. Save scanning & label settings.
Select an element and drag its orange handles to resize it, or enter exact positions and dimensions. Logos support Fit whole image, Crop to fill and Image position. For 3 × 1 inch barcode stock, Use compact 3 × 1 layout replaces the selected draft with a compact starting layout; Undo restores the previous draft. Fit elements to label helps recover elements left outside the label after a size change.
Use the dimensions of the roll actually loaded. If you use 4 × 3 inch stock, enter 4 inches wide and 3 inches high; do not choose a larger stock size merely to make the preview bigger. Resolve any preview errors about text, code spacing or printable bounds before printing.
5Print one slab or rack label
For stock, open Inventory → Scan inventory, choose Print labels and scan or enter the piece’s code. For a rack, open Warehouse Map, select the rack and use Print label for rack.
In Inventory labels, choose the Label template and Printer profile. Set Print connection to Zebra Browser Print (USB / desktop). Check the preview, then click Prepare labels. This option sends the label to the default Zebra device; it does not open the system print dialog.
Inspect the physical label and scan its QR or barcode in Scan for details. Confirm the correct piece or rack opens before printing a batch. A Browser Print submission means the job was sent; still inspect the label at the printer.
6Use the system print dialog or a configured shop connection
If you prefer the operating system’s printer driver or a PDF, choose System print dialog / PDF. Click Prepare labels, then Print labels. Select the printer and matching paper size, use 100% scale with no added headers or margins, and inspect the output. Choose Labels printed correctly only after checking it; otherwise choose Printing cancelled / failed.
A configured SlabBridge shop printer is a separate connection: the profile must select a registered Shop connection, and the installed agent must map that profile’s ID to the local printer. Queue labels uses that configured agent. Selecting this option alone does not install or configure SlabBridge.
A standard ZD621 is suitable for optical QR and barcode labels. RFID encoding needs an RFID-capable model such as ZD621R, compatible tags and a commissioned SlabBridge connection. A phone camera, ordinary label roll or PDF cannot encode RFID. Start with optical labels unless that hardware has been confirmed.
7Recover a queued label without creating duplicates
If Browser Print has no usable default device, SlabOS asks you to choose one or use system printing. The prepared label can remain queued in Recent label jobs. Queued means waiting; it is not proof that paper printed. Check Browser Print on the printing computer before submitting again.
After fixing the connection, use Print queued label for that existing job. You can also select System print dialog / PDF and use Print queued label to prepare it through the normal driver. This reuses the queued job instead of creating another label request.
Refresh reads the stored result. If system printing was cancelled or failed, use Printing cancelled / failed. Cancel / retire label closes an unused queued or failed job where offered. Check the physical printer before cancelling or replacing an uncertain job, because it may already have printed.
8Print from an iPhone or iPad
Zebra Browser Print does not support iOS or iPadOS. Installing it on a Windows computer does not make that computer’s USB printer discoverable in Safari on your phone. The same limitation applies to other iPhone browsers.
For the new Inventory labels workflow, ask your administrator to configure a SlabBridge shop printer under Settings → Inventory → Printers. Select the registered Shop connection and make sure the agent maps the printer profile ID to the physical printer. Keep that shop computer and SlabBridge running.
On your iPhone or iPad, open Print labels, select that SlabBridge Printer profile and choose Queue labels. The shop computer receives the queued job. Check Recent label jobs and inspect the physical label before relying on it. This path requires the shop connection to be commissioned; choosing a profile alone does not connect the hardware.
System print dialog / PDF can only use printers that iOS already exposes through a compatible printing setup. It does not add AirPrint support to a Zebra printer. If no shop connection is configured, print from the supported computer until setup is complete.
9Maintain and verify printer profiles
After saving, reload Printers and confirm the profile name, connection, resolution, media description and Default printer. Branch-specific preferences under Racks & branches can override the shop default for the selected branch. Check those preferences when a print dialog selects a different profile than expected.
Use Remove printer profile only on the intended unneeded profile, then Save scanning & label settings. Removing a SlabOS profile does not uninstall a driver, disconnect hardware or reverse a label that already printed. Keep the profiles and label templates that the shop still uses.
Check the result
- The label has the expected physical dimensions, readable text and a complete QR or barcode with clear space around it.
- A phone scan opens the intended slab or rack, including its correct warehouse and location.
- Repeat the setup check on every computer that will use Zebra Browser Print; its printer selection is local to that computer.
If something looks wrong
- No default printer: open Browser Print, confirm it detects the powered ZD621 and select it as default. Confirm SlabOS is an accepted host and retry. The SlabOS profile name alone does not select the device.
- Printer not detected: check USB or network connection, restart Browser Print, then reopen the label dialog. Review any browser local-device permission prompt. Use the system print option if that computer’s normal driver can print successfully.
- Labels too small, too large or cropped: compare printer DPI, profile DPI, template size and loaded stock. Turn off Fit to page in the system dialog. Width is across the roll; height is the feed direction.
- Blank labels, skipped labels or poor print quality: check media type, ribbon where required, sensor position and calibration using the ZD621 guide. Confirm a printer configuration report is legible before retrying SlabOS.
- An uncertain or failed job may already have reached the printer. Check the physical output and Recent label jobs before cancelling or replacing it; avoid creating duplicate labels blindly.