Pothos (Win10) sdrplay_api_Open() Error: sdrplay_api_Fail


I have followed instructions on the LimeSDR site to install Pothos, and installed the LimeSDR drivers from LimeSDR-USB driver installation - Myriad-RF Wiki (the Zadig instructions on the Pothos site are not applicable), and see in Device Manager that “Myriad-RF LimeSDR-USB” is installed, and then I ran LimeSuite and it advised to upgrade the firmware, which I did as it stated.

I can successfully connect to it using LimeSuite GUI. From the command line, SoapySDRUtil.exe --info shows lime as one of the factories. Executing with --find=“driver=lime” shows that device 0 is LimeSDR-USB.

However, when I run Pothos, and drag a “Soapy SDR Sink” to the main window and set Device Args drop-down to “LimeSDR-USB [USB 3.0]” I can see that the alternating red/green LED becomes just a flashing green LED, so it is talking to the hardware, however in the message window I see this:

[10:51:57.841000] SoapySDR: SoapySDR::Device::enumerate(sdrplay) sdrplay_api_Open() failed
[10:52:02.579000] SoapySDR: sdrplay_api_Open() Error: sdrplay_api_Fail
[10:52:02.579000] SoapySDR: Please check the sdrplay_api service to make sure it is up. If it is up, please restart it.

Googling around suggests that a SDR Play API/HW driver V3.x needs to be installed I think. However, the SDR Play website is now different, and it doesn’t allow such a driver to be installed. I think they only allow downloads for their specific hardware.
The web link:
shows a page briefly for a fraction of a second, but then there is an immediate page redirect to a download page where an ‘RSP’ model needs to be selected.

How can I get Pothos running?

I am running Windows 10.


For the benefit of anyone else experiencing this issue:
To resolve it, I went to:
and selected RSPduo (this was just at random, I don’t know if it makes a difference) and Windows 10, and then selected to download ‘SDRuno’. I installed it, accepting all the defaults. After that, Pothos didn’t generate an error, and I was able to successfully use the SDR Sink.

I’m still learning how to configure that, but for now what worked was:
(a) set Device Args drop-down to “LimeSDR-USB”
(b) set the Sample Rate to 5e6
(c) in the Channels tab, set Frequency to the desired transmit frequency, e.g. 100e6 (obviously terminate the SDR into a load or elsewhere, rather than transmit to the air).

The above steps generate the transmission on both outputs of the LimeSDR. I don’t know what value to type where, to select a particular channel currently.