This issue is not really an issue. It happens whenever you are using more than one
class compliant audio or midi device. A class compliant device means that it does not require any drivers to be loaded, instead the operating system has them already and it loads a generic driver.
The problem under WinXP is that it does not give these devices identifiable names, instead it calls them USB Audio device 1, device2, device 3 etc etc. Not particularly helpful when you have a bunch of class compliant devices in your setup. More annoying is that the name assigned to each device can change depending on what order they are plugged in/switched off and which USB port they occupy (this also links in to the 10 MIDI device entry limit issue in XP - see RME site:
http://www.rme-audio.de/en_support_tech ... q_10entryd)
Microsoft have addressed this issue in Windows 7. Class compliant drivers now appear in the system by their actual name instead of the generic one, which makes identifying each of your USB MIDI devices alot simpler.
IDENTIFYING YOUR DEVICES: Unfortunately I am stuck using WinXP until I get proper audio drivers from Focusrite for Win7, so this may help other XP users with multiple devices to begin with.
First, go to your MIDI prefs and disable ALL control surfaces in the top section. For ALL remaining USB Audio devices in the list enable Track & Remote input.
In a blank MIDI track in session view and select the "MIDI From" dropdown box and select "USB Device 1". Press buttons on all your devices until the MIDI track shows that it is receiving input. Note the device that worked and remember which USB device it is linked to.
Repeat this for USB Device 2, 3 etc etc. You will now know which USB devices are which
physical devices.
Go back to MIDI prefs, enable any control surfaces you require and point them to the USB Audio device numbers you found in the previous step.
**IMPORTANT** Due to the way XP handles MIDI devices, the registry will contain references to each device that is plugged into a USB port and allocate one MIDI entry for it. BUT, if you move this same device to another USB port, IT WILL THEN ALLOCATE ANOTHER MIDI ENTRY TO THE SAME DEVICE. As far as the OS is concerned, you have just connected a new device.
It is therefore recommended that for users with multiple class-compliant USB Audio/MIDI devices that you always plug them into the same USB port each and every time to avoid running out of MIDI entries in the registry (see link to RME website above).
I hope this helps some of you out there, as it has caused me massive problems before (e.g. get on stage in front of a crowd and find that the MIDI device limit has been reached and it won't detect my devices in Live anymore!).
I recommend XP users keep a copy of the information from RME regarding fixing this issue in your gig bag just in case. When you need it you're likely to not remember how to fix it quickly.