USB-to-serial adapter driver on vista64?


I have problem to install the driver for USB-to-serial adapter (PGM02A) on my vista64 machine. The driver actually install but when i plug in the programmer, vista will don´t load the driver… The driver status:

“Windows cannot load the device driver for this hardware. The driver may be corrupted or missing. (Code 39)
Click ‘Check for solutions’ to send data about this device to Microsoft and to see if there is a solution available.”

what to do??

Olle N


Do you have any other computers available on which you can test the programmer?

- Jan

Hello again, yes i have tested it on a laptop with xp running and on that machine the driver works fine…

I was wondering about the operation on another computer more as a hardware test than as a driver test. As far as we know, the driver should work with all Vista versions, but we don’t have much control over the driver, which we get from Silicon Labs. We’ll see if there have been any new versions released. One thing you can try is other ports on your computer and going through a hub. We’ve seen a few cases in the past where a particular combination of ports or devices cause problems with the driver.

- Jan

It looks like the 64-bit version of Vista doesn’t allow non-certified drivers. We don’t have the resources to get the driver certified, but it looks like you might be able to get around Vista x64’s certified driver enforcement:

Can you let me know if that works?

- Jan

No, this method did not work for me. I tried both command prompt suggestions in that link. I have vistax64 business edition and am trying to use the usb-serial adapter with the same issue. as nobody replied to your question of “did this work” i thought I would let you know

Hello, Nike.

Thanks for letting us know. Microsoft released a windows update a while ago that caused the method described in the link above to stop working.

But there are two other methods for disabling the driver signing requirement in Windows Vista 64-bit edition, and I tested both of them a week ago and they both worked.

The simplest method is when you are booting up windows, press F8 to bring up the Advance Boot Options Menu. Select “Disable Driver Signature Enforcement” and press enter. When windows is done booting, you should be able to use our CP2102 drivers. You will still get error messages from windows about the drivers having invalid signatures, but you will be able to use the device. You must remember to do this every time you boot up Windows, or else you will not be able to use the drivers for that session.

Another method is to download a third party utility called the Driver Signature Enforcement Verifier.

  1. Download the utility from
  2. Use the utility to Enable Test Mode.
  3. Reboot your computer. You should now see the words “Test Mode” written in all four corners of your desktop.
  4. Use the utility to sign the following system files:
    • C:\Windows\system32\drivers\slabbus.sys
    • C:\Windows\system32\drivers\slabcm.sys
    • C:\Windows\system32\drivers\slabcmnt.sys
    • C:\Windows\system32\drivers\slabser.sys
    • C:\Windows\system32\drivers\slabwh.sys
    • C:\Windows\system32\drivers\slabwhnt.sys
  5. Unplug and replug your device, and it should work.

Please let us know if these methods work for you!