>Psychtoolbox>PsychHardware

[keypadIndices, productNames, allInfos] = GetKeypadIndices([productName][, serialNumber][, locationID])

The PsychHID assigns each USB HID device connected to you computer a
unique index. GetKeypadIndices returns the indices for those HID
devices which are keypads. The product names of each keypad are
returned in a second argument which is useful to identify the keypad
associated with an index. The third return argument is a cell-array with
complete information about the keypad device, e.g., allInfos{1} returns
all known info about the 1st detected keypad.

If you have multiple keypads connected you can restrict the set of
returned keypads by specifying the following optional match-critera:

product = Product name of target devices, as returned in ‘productNames’.

serialNumber = Serial number of target devices. This is a text string,
not a number!

locationID = Numeric id of where the device is connected to the
computer. The number is supposed to be unique for a given
connection port. E.g., the same number will be returned
whenever the device is connected to the same USB port of
the computer. The value should be persistent across
reboots of the machine, but may not be persistent across
operating system upgrades - or may not be persistent at
all in case of os bugs. Your mileage may vary…
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WINDOWS: All keypads are treated as one keypad, you can not select between
different keypads.

see also: GetGamepadIndices, GetKeyBoardIndices