The majority of MIDI applications (such as your DAW) on Windows are single-client - this means that if a class-compliant USB-MIDI device (such as any Modal device) is connected to an application then it cannot be connected to a second application until disconnected from the first. The MIDI device may appear as an available device in multiple applications, however once it connects to the first application it will 'lock' the device from being used elsewhere, and any attempt to connect to it in a second application will have no effect. This is known as the Windows single-client MIDI issue, and is an issue for any Class Compliant USB MIDI device and not an issue specifically with Modal devices.
The most common situation where you may run into this issue is when attempting to send MIDI to the Modal device from your DAW and use MODALplugin simultaneously*. In most cases, when you launch your DAW it will grab the connection to your Modal USB-MIDI device which will then prevent MODALplugin from being able to connect to the same device. You can resolve this by going into your DAWs MIDI preferences and disabling / disconnecting from the Modal device, and then re-attempting to connect to the device in MODALplugin. There are then two options for sending MIDI to the Modal device from your DAW and using MODALplugin simultaneously:
- Use the MODALplugin 'Host MIDI Routing' feature for routing MIDI messages from your DAW track directly to the connected Modal device, as an alternative to using the DAWs main MIDI output.
- Connect your DAW to the Modal device using a USB-MIDI interface connected to the DIN MIDI input of the Modal device, leaving the Modal device USB port available for MODALplugin to connect to.
For more information on these options, please see this article.
You will also run into this issue if attempting to connect your Modal device to both MODALapp and your DAW simultaneously - the solution to this is to first disconnect the Modal USB-MIDI device from your DAW (leaving the USB port available for MODALapp to connect to) and then connecting your DAW to the Modal device using a USB-MIDI interface connected to the DIN MIDI input of the Modal device.
*Please note that the Windows OS sees MODALplugin (or any other audio plugin) as a separate application from your DAW, even though is it being run from your DAW.