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IntegrationsPrintingPrint from a tablet or phone

Print from a tablet or phone

Connect a tablet or phone to the QZ Tray on your computer so you can print receipts, labels and documents from it.

Updated 4 min read

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Some shops run their POS on a tablet or phone. QZ Tray itself always runs on a computer, a Mac or a PC that your printer is connected to. The tablet or phone connects to that computer over your Wi-Fi.

This is a technical setup. It works best if you are comfortable with a command line, or if someone who looks after your computers does it. Prefer not to do it yourself? Contact support, and support can help you.

What you need

  • The tablet or phone and the computer on the same Wi-Fi network.
  • QZ Tray installed on the computer, with the printer set up.
  • Printing from that computer already working. Test this first, so you know the printer itself is fine before you add the network.

1. Find the computer's IP address

The tablet or phone connects to the computer's local Wi-Fi IP address, for example 10.20.2.88. This must be the local address of the computer on your Wi-Fi, not a public IP address or a domain. Look it up in the Wi-Fi settings of the computer.

Some routers hand out a new IP address from time to time. If printing from the tablet or phone suddenly stops, a changed IP address is the first thing to check. Repeat the steps below with the new address.

2. Create a certificate for that address

QZ Tray's certificate only works for localhost. Create a new one that covers the IP address and localhost together. Always include both, so printing from the computer itself keeps working.

macOS

  1. Quit QZ Tray completely: right-click the QZ Tray icon and choose Quit. Closing the window is not enough.

  2. Open Terminal.

  3. Run this command, with your own IP address instead of 10.20.2.88:

    bash
    sudo "/Applications/QZ Tray.app/Contents/MacOS/QZ Tray" certgen --hosts "10.20.2.88,localhost"

  4. Enter the computer's password when asked. QZ Tray needs admin rights to update its files.

  5. Start QZ Tray again.

Windows

  1. Quit QZ Tray completely: right-click the QZ Tray icon in the system tray and choose Exit.

  2. Open Command Prompt as administrator.

  3. Run this command, with your own IP address instead of 10.20.2.88:

    text
    "C:\Program Files\QZ Tray\qz-tray.exe" certgen --hosts "10.20.2.88,localhost"

  4. Start QZ Tray again.

3. Get the certificate to the tablet or phone

The command creates a file called root-ca.crt in the QZ Tray folder. It is usually here:

  • macOS: /Applications/QZ Tray.app/Contents/Resources/root-ca.crt
  • Windows: C:\Program Files\QZ Tray\root-ca.crt

The exact path can differ a little per installation. If it is not there, search the QZ Tray folder for root-ca.crt. Then get the file onto the tablet or phone, for example by email, a USB cable or a cloud drive.

4. Trust the certificate on the tablet or phone

The tablet or phone must trust the certificate. Otherwise its browser refuses the secure connection to QZ Tray.

Android

  1. Open Settings, then Security. On some devices it is under Security, then Encryption & credentials.
  2. Choose Install a certificate, then CA certificate.
  3. Confirm the warning about installing a CA certificate.
  4. Select root-ca.crt.
  5. Close the browser you use for the POS completely and open it again.

The menu names differ a little per Android version and brand, but it is always under the security settings.

iPhone and iPad

  1. Open root-ca.crt on the device, for example from the email, from Files or from AirDrop. iOS says the profile was downloaded.
  2. Open Settings. At the top you see Profile Downloaded. Tap it, then tap Install and enter your passcode.
  3. Go to Settings, then General, then About, then Certificate Trust Settings.
  4. Under Enable full trust for root certificates, switch on the certificate you just installed.
  5. Close the browser you use for the POS completely and open it again.

Step 4 is easy to miss. Without it, iOS installs the certificate but does not trust it.

5. Connect to the computer

On the tablet or phone, open Settings, then Integrations, and find the QZ Tray card. Click Advanced settings, enter the computer's IP address as the host and click Connect.

The Advanced settings link only shows while QZ Tray is not connected. If you do not see it, the browser is already connected, probably to localhost. Disconnect first and the link appears.

If it stops working

Print from the computer itself first. That tells you where the problem is.

  • Printing from the computer works, from the tablet or phone it does not: most likely the IP address changed. Check the computer's current IP address against the host on the tablet or phone. If they differ, repeat step 2 with the new address and update the host in step 5.
  • Printing from the computer does not work either: the problem is QZ Tray or the printer, not the tablet setup. See troubleshooting.