Troubleshooting

Tip

First steps when something does not print:

  1. Go to Configuration ‣ Printers.

  2. Click Reset printer queue to clear any stuck jobs.

  3. If the issue persists, click Restart controller to restart the service.

These two actions resolve most printer controller issues.

Basic printer checks

Before troubleshooting the software, verify the following on the printer itself:

  • The printer is powered on and shows no error lights (red or orange).

  • Paper or label rolls are loaded and not empty.

  • The cover is fully closed—many printers refuse to print if the cover is not latched.

  • There are no paper jams—check for stuck paper or labels inside.

  • The printer is online, not paused or in offline mode.

Tip

Most printer issues come from empty paper, an open cover, or the printer being in an error state. Always check these first.

Connection issues

Printer controller not connected:

  1. Check that the controller is powered on and connected to the network.

  2. Make sure the controller can reach your Gem Logic instance (no firewall blocking it).

  3. The connection indicator turns green once the controller polls successfully (within 15 seconds).

Print jobs stuck in Pending:

  1. Check that the controller is connected (green indicator).

  2. Use Reset printer queue to clear stuck jobs.

  3. Verify the printer name matches exactly what Windows shows.

Printer name issues

The printer name in Gem Logic must exactly match the name shown in Windows:

  1. On the printer controller PC, open Settings ‣ Devices ‣ Printers & Scanners.

  2. Copy the exact printer name, including any model numbers or network suffixes.

  3. Paste it into the matching field in Gem Logic.

Warning

Printer names are case-sensitive. HP LaserJet is different from HP Laserjet.

Reset options

Two reset actions are available on each controller card:

  • Reset printer queue: clears all pending print jobs for that controller. Use it when jobs are stuck.

  • Restart controller: restarts the printer controller service. Use it when the controller is unresponsive.

Receipt printer issues

Logo not printing:

  • Make sure the logo is a monochrome BMP file (1-bit color depth).

  • A width of around 384 pixels works well for 58 mm thermal printers.

Characters garbled or wrong encoding:

  • Make sure the receipt printer supports ESC/POS commands.

Cash drawer not opening:

  • Check that the cash drawer is connected to the receipt printer’s kick-out port.

  • The receipt printer must support cash drawer commands.

Label printer issues

Labels not printing correctly:

  • Verify the label dimensions match your physical labels (width and length in dots).

  • At 203 DPI: 1 inch = 203 dots and 1 mm ≈ 8 dots.

  • Use the label preview to check the design before printing.

QR codes not scanning:

  • Leave enough quiet zone (empty space) around the QR code.

  • Increase the QR code size in the ZPL design if needed.

  • Make sure the {ean_code} variable contains valid data.

If none of these steps resolve the problem, contact Gem Logic support for further assistance.