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Error: Cannot access RTL device

Posted: Thu Apr 20, 2017 6:35 am
by darrenyorston
I have been using my NooElec RTL2832U with SDR# fine. Went to start it today and now SDR# is reporting the error "Cannot access RTL device" when I click the play button. When I go to settings mu device is shown correctly and RTL-SDR (USB) is selected in the source.

I have tried reinstalling the device drivers in Zadig with Administrator rights and have confirmed that the SDR-x86 folder is not read only.

I have tried changing ports with the USB dongle and reinstalling drivers however still get the same message.

Any ideas as to the problem?

Re: Error: Cannot access RTL device

Posted: Fri Apr 21, 2017 12:42 am
by rtlsdrblog
Double check that the rtlsdr.dll file is still in the folder.

Also try it on another PC to rule out a hardware fault.

Re: Error: Cannot access RTL device

Posted: Mon Apr 24, 2017 2:06 am
by darrenyorston
I can successfully install SDR# on my laptop. Interestingly when I run Zadig it detects the "bulk interface 0" that people keep mentioning.

On my desktop I uninstalled the device "RTL2838UHIDIR" device from Device Manager and also deleted SDR#. I downloaded the latest x64 version and installed it. Alas running "install-rtlsdr" does not work so I did a manual install as per the quick start guide. When I run Zadig it does not find a device and I need to select Options-List All Devices and then select "RTL2838UHIDIR", no "bulk interface 0" is displayed.

When I run SDRSharp I receive the "Cannot access RTL device" message.

rtlsdr.dll is in the folder and is not read only.

Re: Error: Cannot access RTL device

Posted: Mon Apr 24, 2017 5:20 am
by rtlsdrblog
RTL2838UHIDIR is also a valid selection for zadig. Does the driver install work? What driver does it show on the left of the green arrow now? That box shows the currently installed driver, it should be WinUSB.

Some Windows systems seem to aggressively overwrite the zadig drivers with broken Windows ones within seconds of using zadig. If it seems to be doing that make sure that automatic driver updates are turned off in Windows.

Re: Error: Cannot access RTL device

Posted: Mon Apr 24, 2017 6:01 am
by darrenyorston
I kept uninstalling the device driver via COntrol Manager and deleting the SDR# folder. After doing this four times SDR# is now working. Pretty annoying.

The driver is shows to the left is WinUSB (v6.1.7600.16385). Its the same one it installs. Windows 10 detects it this way by default.

Only thing I have noted is that the WCID checkbox is always showing a red cross. Under Windows 8.1 it always showed a green tick.

Re: Error: Cannot access RTL device

Posted: Tue Apr 25, 2017 9:23 am
by rtlsdrblog
If it stops working again, check to see what driver is installed in device manager.

I have a feeling that your Windows is overwriting the drivers.

Re: Error: Cannot access RTL device

Posted: Sat Oct 12, 2019 8:25 pm
by Winmocktor
darrenyorston wrote:
Mon Apr 24, 2017 6:01 am
I kept uninstalling the device driver via COntrol Manager and deleting the SDR# folder. After doing this four times SDR# is now working. Pretty annoying.

The driver is shows to the left is WinUSB (v6.1.7600.16385). Its the same one it installs. Windows 10 detects it this way by default.

Only thing I have noted is that the WCID checkbox is always showing a red cross. Under Windows 8.1 it always showed a green tick.
Having Same issue. used to be a Green Check now a red X and my RTL-SDR stops working. I can get it to work for about 1 Second if I unplug it and plug it back in. Not sure whats happening.

Re: Error: Cannot access RTL device

Posted: Wed Oct 16, 2019 5:39 pm
by bmh
The latest Windows 10 update hosed my drivers for my RTL dongle AGAIN. For some reason when I ran Zadig to try to reinstall it Zadig would appear to be working for a minute or so and then would end with a message saying "program terminated by user input" even though I didn't cancel anything. I have had much better luck using the tool located on this page... https://visualgdb.com/UsbDriverTool/

Re: Error: Cannot access RTL device

Posted: Tue Oct 29, 2019 10:36 am
by Jdos222
Hi,
I had this exact problem. I tried different ports, re-installed drivers etc, nothing worked.
Found out that it was a simple fix: the frequency in SDR# had been bumped up to 2.55 GHz. This is outside the range of the my RTL device, so when I pressed play it was asking the RTL to go to an impossible frequency and an error was returned. Once I adjusted the frequency back into the RTL's range it worked fine.
Hope this helps!