NRPN

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NRPN stands for "Non-Registered Parameter Number" and is part of the MIDI specification for control of electronic musical instruments. NRPNs allow for manufacturer-specific or instrument-specific MIDI controllers that are not part of the basic MIDI standard.

Unlike other MIDI controllers (such as velocity, modulation, volume, etc), NRPNs require more than one piece of controller data to be sent. First, controller 98 - NRPN Most Significant Bit (MSB) - followed by 99 - NRPN Least Significant Bit (LSB) sent as a pair specify the parameter to be changed. Controller 6 then sets the value of the parameter in question. Controller 38 may optionally then be sent as a fine adjustment to the value set by controller 6.

Consequently, NRPNs allow for MIDI control of a vastly greater number of parameters than the basic 128 set out in the basic MIDI standard. Since the values of those parameters may be set by two separate controllers (ie. both 6 and 38), NRPNs also allow a much greater resolution than conventional MIDI controllers, which have only 128 possible values.

[edit] See also

• RPN (Registered Parameter Number)
• SysEx (System Exclusive)