Lava y Ya supports three connection modes for thermal receipt printers. The correct mode depends on your operating system and the type of printer you have.
Connection modes overview
Go to Settings → Printer and choose the mode that matches your setup:
Bluetooth — For wireless (BLE) printers. Works on Android, Windows, and Mac with Chrome or Edge. No driver required.
Direct USB (Mac / Linux) — For USB printers connected directly to a Mac or Linux machine. No driver installation required. Sends ESC/POS commands directly to the device.
USB (Mac/Win) — "Save as Windows Printer" — Uses the browser's native print dialog. Requires the printer to be installed as a system printer with its manufacturer driver.
Direct USB (Mac / Linux)
This mode uses Chrome's Web USB API to talk directly to the printer, bypassing the operating system's print spooler entirely.
Why does no port appear?
The Serial Port mode looks for COM or Serial ports — communication channels that the OS creates automatically when it detects a compatible device. On Windows this shows up as COM3, COM4, etc. On Mac as /dev/cu.usbserial-XXXX.
Most USB thermal printers do not create that port on Mac. Instead of presenting themselves as a serial device, they present as a "USB printer" (USB class 7). macOS recognizes them as a device but does not assign a serial port, so clicking "Search for Serial Printer" shows nothing.
Direct USB avoids this problem by talking to the printer directly over its USB connection, without relying on the OS to create a port. The result is identical to Bluetooth mode: native ESC/POS commands, instant printing, no dialogs.
How to set it up
Connect the printer via USB and turn it on.
In Settings → Printer, select the Serial Port tab.
Click "Direct USB (Mac / Linux)". Chrome will show a USB device picker — select your printer.
Click Save. From now on each receipt will be sent directly to the printer with no extra dialogs.
USB (Mac/Win) — Printer with manufacturer driver
This mode uses the browser's native print dialog (window.print). The browser renders the receipt as an HTML page and sends it to the OS print spooler (CUPS on Mac, spooler on Windows). You choose the printer in the dialog that appears.
How to set it up
Connect the printer via USB and install the manufacturer driver on your computer.
Verify it works by printing a test page from System Settings → Printers (Mac) or Devices and Printers (Windows).
In Settings → Printer, select the USB (Mac/Win) tab and click "Save as Windows Printer".
When printing a receipt, the browser dialog will open — select your thermal printer and set the paper size to 80 mm or 58 mm depending on your model.
Which mode should I use?
Mac with USB printer → use Direct USB. No driver needed, no print dialog, the receipt prints instantly.
Windows with USB printer → use USB (Mac/Win) if you already have the driver installed, or Serial Port if the printer creates a COM port.
Wireless (Bluetooth) printer → use Bluetooth mode regardless of operating system.