How to Get Input from a Barcode Scanner in a Batch Script

Integrating a barcode scanner into a batch script can dramatically speed up data entry for tasks like inventory management, asset tracking, or point-of-sale systems. While it might seem like a complex hardware integration problem, the solution is surprisingly simple. Most modern USB barcode scanners are designed to behave in a very user-friendly way: they emulate a keyboard.

This guide will explain this "keyboard wedge" concept and teach you how to use the standard SET /P command to reliably capture input from a barcode scanner in your batch scripts, just as if a user were typing the numbers in manually.

The Core Concept: Keyboard Emulation

The vast majority of modern USB barcode scanners are configured as "keyboard wedge" or "HID" (Human Interface Device) devices. This means that when they scan a barcode, they do two things:

1. They instantly "type" the numbers or characters from the barcode.
2. They then automatically "press" the Enter key.

To the operating system and your batch script, there is no difference between a user typing 12345 and pressing Enter, and a scanner scanning a barcode for 12345. This makes capturing the input incredibly easy.

The Core Command: SET /P

Since the scanner is emulating a keyboard that types a string and then presses Enter, the perfect command to capture this is SET /P. This command displays a prompt and waits for the user (or the scanner) to provide a line of input, which is terminated by the Enter key.

Syntax: SET /P "VariableName=Prompt for user: "

Basic Example: Capturing a Single Barcode

This script will prompt for a scan, wait for the barcode scanner to provide input, and then display the data it received.

@ECHO OFF
TITLE Barcode Scanner Input

ECHO --- Please scan a barcode now ---
ECHO.

SET "BarcodeData="
SET /P "BarcodeData=Scan item: "

ECHO.
ECHO --- Data Received ---
ECHO Scanned data: %BarcodeData%
ECHO.
PAUSE

The script will pause and wait for input.

--- Please scan a barcode now ---

Scan item:

When you scan a barcode (e.g., for "9780141036144"), the scanner will instantly populate the line and press Enter.

Scan item: 9780141036144

--- Data Received ---
Scanned data: 9780141036144

Press any key to continue . . .

Creating a Continuous Scanning Loop

For inventory or check-in systems, you'll want the script to be ready for the next scan immediately after the last one. A simple GOTO loop is perfect for this.

@ECHO OFF
TITLE Continuous Barcode Scanner
:ScanLoop
    CLS
    ECHO --- Ready for next scan ---
    ECHO (Scan a barcode or type 'exit' and press Enter to quit)
    ECHO.
    
    SET "BarcodeData="
    SET /P "BarcodeData=Scan item: "
    
    REM Check if the user wants to exit
    IF /I "%BarcodeData%"=="exit" GOTO :EOF
    
    REM Process the data (in this case, just display it)
    ECHO Scanned: %BarcodeData%
    
    REM Add the data to a log file
    ECHO %DATE% %TIME% - %BarcodeData% >> scan_log.txt
    
    ECHO Item logged. Pausing for 2 seconds...
    TIMEOUT /T 2 > NUL
    
    GOTO :ScanLoop

Common Pitfalls and How to Solve Them

The Scanner's "Enter" Suffix

The entire system relies on the scanner being configured to send an "Enter" (Carriage Return/Line Feed) suffix after it transmits the barcode data. This is the default setting for almost all scanners.

Solution: If your script is not reacting to a scan, the first thing to check is the scanner's configuration. Most scanners are configured by scanning special barcodes in the user manual. Ensure that the "CR/LF Suffix" or "Enter Key" option is enabled.

Handling Accidental Keyboard Input

Because the scanner is a keyboard, your script can't tell the difference if a user accidentally types something into the command prompt and presses Enter.

Solution: This is generally not a problem and is often a feature. It allows a user to manually type in a barcode number if a label is damaged and won't scan. If you need to prevent this, a more advanced language (like PowerShell or C#) that can interact with specific hardware devices would be required.

Clearing the Variable Before Each Scan

This is a critical best practice for SET /P. If the user (or scanner) provides empty input (e.g., by just pressing Enter), the variable is left unchanged.

Solution: As shown in the loop example, always clear your variable (SET "BarcodeData=") immediately before the SET /P prompt. This ensures you don't accidentally process the same data twice.

Practical Example: A Simple Inventory Counter

This script allows a user to scan items to count them. It stores the results in a temporary file and uses find to count how many times each item has been scanned.

@ECHO OFF
SETLOCAL ENABLEDELAYEDEXPANSION
SET "InventoryFile=%TEMP%\inventory_session.txt"
IF EXIST "%InventoryFile%" DEL "%InventoryFile%"
TITLE Inventory Counter

:ScanLoop
    CLS
    ECHO --- Inventory Scan ---
    ECHO Scanned items will be logged to: %InventoryFile%
    ECHO (Type 'report' to finish, 'exit' to quit)
    ECHO.
    
    SET "Barcode="
    SET /P "Barcode=Scan item: "
    
    IF /I "%Barcode%"=="exit" GOTO :End
    IF /I "%Barcode%"=="report" GOTO :ShowReport
    
    ECHO !Barcode! >> "%InventoryFile%"
    ECHO Logged: !Barcode!
    TIMEOUT /T 1 > NUL
    GOTO :ScanLoop

:ShowReport
    CLS
    ECHO --- Final Inventory Report ---
    FOR /F "delims=" %%I IN ('SORT "%InventoryFile%" ^| UNIQ -c') DO (
        ECHO   %%I
    )
    PAUSE
    GOTO :ScanLoop
    
:End
DEL "%InventoryFile%"

note

This advanced example uses SORT and UNIQ (if available from Git for Windows or similar toolsets) to generate the final count.

Conclusion

Integrating a barcode scanner with a batch script is a surprisingly simple and powerful way to automate data entry.

Key takeaways:

• Most USB barcode scanners act as a keyboard emulator that types the data and presses Enter.
• The SET /P command is the perfect tool to capture this input.
• For continuous scanning, use a GOTO loop.
• Always clear your variable (SET "Var=") before each SET /P prompt to prevent errors from empty input.

By using this simple technique, you can create efficient and user-friendly scripts for a wide range of inventory and data-capture tasks.