Controller

Category: Voice

Purpose

Sets a particular controller's value. A controller is any switch, slider, knob, etc, that implements some function (usually) other than sounding or stopping notes (ie, which are the jobs of the Note On and Note Off messages respectively). There are 128 possible controllers on a MIDI device. These are numbered from 0 to 127. Some of these controller numbers are assigned to particular hardware controls on a MIDI device. For example, controller 1 is the Modulation Wheel. Other controller numbers are free to be arbitrarily interpreted by a MIDI device. For example, a drum box may have a slider controlling Tempo which it arbitrarily assigns to one of these free numbers. Then, when the drum box receives a Controller message with that controller number, it can adjust its tempo. A MIDI device need not have an actual physical control on it in order to respond to a particular controller. For example, even though a rack-mount sound module may not have a Mod Wheel on it, the module will likely still respond to and utilize Modulation controller messages to modify its sound. If the device is a MultiTimbral unit, then each one of its Parts may respond differently (or not at all) to various controller numbers. The Part affected by a particular controller message is the one assigned to the message's MIDI channel.

Status

0xB0 to 0xBF where the low nibble is the MIDI channel.

Data

Two data bytes follow the Status.

The first data is the controller number (0 to 127). This indicates which controller is affected by the received MIDI message.

The second data byte is the value to which the controller should be set, a value from 0 to 127.

Errata

An All Controllers Off controller message can be used to reset all controllers (that a MIDI device implements) to default values. For example, the Mod Wheel is reset to its "off" position upon receipt of this message.