How to troubleshoot and fix a barcode scanner or receipt printer not working with your POS system

Hardware & Peripherals KB-456

Summary

This guide helps you troubleshoot and resolve: How to troubleshoot and fix a barcode scanner or receipt printer not working with your POS system. Follow the steps below to fix the issue.

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Common Causes

Barcode scanners and receipt printers are essential peripherals for any point-of-sale (POS) setup. When they stop working, it can bring transactions to a grinding halt. This guide walks you through diagnosing and resolving the most common issues with these devices, whether they connect via USB, Bluetooth, serial, or network. Most problems fall into a few categories: loose or faulty cabling, driver or configuration issues, incorrect POS software settings, or the device itself needing a reset.

Quick Fix Steps

If your barcode scanner or receipt printer has stopped working, try these steps in order before diving into detailed troubleshooting:

Check that all cables are firmly seated at both ends, or that the Bluetooth pairing is still active.
Power cycle the device by turning it off, waiting 10 seconds, then turning it back on.
Restart your POS terminal or computer.
Confirm the device appears in your operating system's hardware list.
Test the device with a different USB port or cable if available.

If the device works after a restart but fails again later, the issue is likely a driver, software, or power management setting rather than faulty hardware.

Detailed Instructions

Check the Physical Connection

Loose or damaged cabling is the single most common cause of peripheral failure.

USB devices: Unplug the scanner or printer, inspect the connector for bent pins or debris, then plug it into a different USB port. Avoid USB hubs if possible — connect directly to the terminal.
Serial (RS-232) devices: Confirm the serial cable is secured with thumbscrews at both ends. Verify the correct COM port is selected in your POS software.
Network/Ethernet receipt printers: Check that the Ethernet cable is clicked in firmly and the link light is active on the printer.
Bluetooth devices: Confirm the device is still paired and within range. See How to connect Bluetooth devices for pairing instructions.

Verify the Device Is Recognised by Your Operating System

Windows 10/11:

Right-click the Start button and select Device Manager.
Expand Human Interface Devices for scanners, or Printers and Ports (COM & LPT) for receipt printers.
Look for any device with a yellow warning triangle, which indicates a driver issue.

macOS:

Open System Settings > Bluetooth to verify wireless devices are connected.
Open System Information > USB (or Bluetooth) to confirm wired devices are detected.

If the device doesn't appear at all when plugged in, try a different cable. Cables fail more often than the devices themselves.

Resolve Driver Issues on Windows

Outdated or corrupted drivers frequently cause peripherals to stop responding.

In Device Manager, right-click the affected device and select Update driver.
Choose Search automatically for drivers.
If Windows cannot find a driver, visit the manufacturer's website (Epson, Star, Zebra, Honeywell, Datalogic, etc.) and download the latest driver for your specific model.
Install the driver, then restart the POS terminal.

Always download drivers from the official manufacturer website. Third-party driver sites frequently bundle unwanted software.

Configure Your POS Software

Even when the hardware is working correctly, the POS software must be pointed at the right port or device.

Barcode scanner: Open your POS settings and confirm the scanner is enabled. Most POS systems require you to select the scanner from a list of detected devices or assign it to a specific input mode (keyboard wedge, HID, or serial).
Receipt printer: Verify the printer is selected as the default receipt printer in your POS configuration. Check that the port setting matches the physical connection — for example, COM3 for a serial connection, or the printer's IP address for a network connection.
Many POS applications require you to test print or test scan from within the settings menu to confirm the device is configured correctly.

Reset the Barcode Scanner

Scanners sometimes lose their configuration or get stuck in a particular mode. Most scanners can be reset to factory defaults by scanning a special barcode from the user manual.

Locate the user manual or quick-start guide that came with your scanner.
Find the Factory Default or Reset to Defaults barcode.
Scan the barcode with the scanner.
Reconfigure any custom settings (such as enabling or disabling specific barcode symbologies) by scanning the corresponding setup barcodes from the manual.

If you've misplaced the manual, search the manufacturer's website using your scanner's model number. Most manuals are available as PDFs.

Clear the Receipt Printer Queue

A stuck print queue can prevent new receipts from printing, especially on Windows.

Open Settings > Bluetooth & devices > Printers & scanners.
Select your receipt printer and click Open print queue.
Click Printer in the menu bar and ensure Use Printer Offline is unchecked.
Click Cancel all documents to clear any stuck jobs.
Try printing a test page from this window.

Check Power and Paper (Receipt Printers)

Confirm the printer's power LED is on and the power brick is firmly connected.
Open the lid and check that thermal paper is loaded correctly, with the paper feeding from underneath the roll.
Ensure the paper roll isn't empty or jammed.
Close the lid firmly — most thermal printers won't print if the lid is open.

Troubleshooting Specific Scenarios

Scanner Beeps but No Data Appears in POS

This usually means the scanner is configured for the wrong interface mode.

Check that the scanner is set to USB Keyboard or HID mode if your POS expects keystroke input.
Some POS systems require Serial mode instead — consult your POS documentation.
Open a text editor like Notepad and scan a barcode. If the numbers appear there, the scanner is working and the issue is with your POS configuration.

Receipt Printer Prints Garbled Text

Garbled output typically indicates a baud rate or character set mismatch.

For serial printers, verify the baud rate in your POS software matches the printer's DIP switch or software setting (commonly 9600 or 38400).
Check that the character encoding is set to match your POS — many receipt printers default to CP437 or CP850.
Update or reinstall the printer driver from the manufacturer's website.

Device Works on One USB Port but Not Another

This usually points to insufficient power or a faulty port.

Some barcode scanners require more power than certain USB ports can supply. Try a powered USB hub.
Avoid connecting through an unpowered USB hub if possible — connect directly to the terminal.
Test the device on a known-good port to confirm whether the original port is faulty.
If the device only works on specific ports, label those ports and avoid using the faulty ones.

If none of the steps above resolve the issue, the device may have a hardware fault. Contact your POS hardware supplier or the manufacturer for warranty or repair options.

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