Fun with legacy barcode scanners and PS/2 to USB adapters

So one of the "joys" of upgrading hardware is inevitably you have some sort of legacy component that still needs to work with the new system.  For us it was our barcode scanners as legacy components as I upgrade our staff computers.  Computers that work are awesome, even more so when they work well.  Unfortunately we have a slew of barcode scanners with PS/2 connectors intended to share a port with a PS/2 keyboard.

Simple solution, right?  Just get a PS/2 to USB adapter, plug tab a into slot b, and go!  As it turns out, not so much.  I can connect everything, the scanner is powered, but when I scan a barcode I get only a few characters printed to screen.  Now, in the past I was provided with several $30 adapters from Staples that worked like a charm.  This time around I am in the position of making most technology purchase recommendations, and I went for a generic adapter from Monoprice.  At $6 total for shipping and two adapters, I hold the brief hassle of figuring this out was a reasonable trade off.

I got our scanner working largely by following the instructions from a blog post titled "Metrologic Laser Scanner fun-ness," refreshing after the many less-than-useful forum discussions results, well seasoned with sales sites.  Honeywell tech support will not help with this unless you use their ($50) adapter cable, and no drivers exist for using this scanner with Windows 7.

These are instructions for if you have an adapter that seems to properly power the scanner but nothing prints to screen (if the adapter doesn't power the scanner then there is likely a problem with the adapter).  Hopefully these will be useful to someone else searching for this solution.

Required components:
-Metrologic barcode scanner (ours are MS9520)
-generic PS/2 to USB adapter
-PS/2 keyboard
-Your scanner's Single-Line Configuration Guide (or you can try this PDF manual:

The process:
1. Plug PS/2 to USB adapter into your PC, let it finish identifying drivers and all that.
2. Plug keyboard into adapter to "prime" it as a keyboard.  If the keyboard works, unplug the keyboard from the adapter.
3. Plug the scanner into the adapter (make sure to use the same socket you used for the keyboard if it is a Y shaped adapter).
4. Locate the following barcodes in your Configuration Guide and scan them, the scanner will make a series of chirping beeps as it reprograms itself:
-Enable Stand-Alone Keyboard Scanner
-Inter-Scan Code Delay 7.5 msec
-10 msec Intercharacter Delay

You should be able to now correctly scan in barcodes.

A quick warning!  This will scan in barcodes slightly slower, but the 1 msec Intercharacter Delay results in a very high frequency of incomplete scans, so these are the two shortest delay options.


  1. A massive thank you as I was ^pulling my hair trying to resolve the same problem!

  2. Just to add my thanks. I had battled with this exact same issue for a couple of days. The last piece of the jigsaw was setting the Inter-Scan Code Delay to 7.5 msec as I had already found that the 10 msec Intercharacter Delay had improved the read.

    Up until this last change the scan was dropping any character that repeated e.g.11223344 was being scanned as 1234, most infuriating! The Inter-Scan Code Delay of 7.5 msec fixed this :-) Thanks again & Happy New Year

  3. Hello T,

    This is a great post, however, before getting the adapters, one of my friends gave me a USB cable from another Metrologic scanner he is not currently using.

    I have changed the cables, but I am not sure what configuration I should use to enable the current MS9520 (F)47 KB WEDGE to work using the USB cable.

    Any help?

    1. Hi,

      Sorry I didn't respond in at all a timely manner. I haven't worked with that specific set up so I haven't had the opportunity to figure it out. Hope you managed it.

  4. Thank you buddy! I was facing the same problem on my organization. We have several barcode readers and need all of them working, so your text made it possible.

    Thank you for your information and effort. Hope you get this message

  5. thank you very much with my whole heart

  6. Thank you very very much!.. bless you and your family!
    You saved me a lot of headache

  7. I would have never been able to do this without you. Thanks, T! With that said, Id like to insist that you accept my sincere gift- my liver. I will keep it until you need it, but please, consider it yours. With my scanner happily scanning once again I can get back to the little things that make life worth living, like pulling Dorothée's hair.

  8. nice blog!!! Thanks for posting this blog..I also recommended a trusted supplier of barcode scanner in Anaheim, CA. For more information visit @

  9. Best Selling Honeywell Barcode Scanner in Uae, Youjie ZL2200 Barcode Scanner in Uae, Single-Line Laser Barcode Scanner in Uae


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