How to check MIDI modulation wheel messages

You move a MIDI foot pedal expecting it to control modulation, but the sound does not change. The pedal may be sending a different message, such as expression, or it may not be sending MIDI input at all.

Use the MIDI Test to check the messages reaching your browser. You can see whether the pedal sends a control change, which controller number it uses, and how its value changes as you move it.

Check the pedal's MIDI messages

1. Connect the foot pedal to a MIDI keyboard or controller, then open the MIDI Test on a supported browser. MIDI Test does not work in Safari.
2. If the browser asks for MIDI access, allow it. Choose the connected keyboard or controller from the available MIDI inputs if there is more than one.
3. Move the pedal slowly from its resting position to its full range. If it is a switch pedal, press and release it several times instead.
4. Watch the incoming messages while you move the pedal. Look for a control-change message and note its controller number, channel, and changing value.
5. Move the pedal through its range again, pausing at the bottom, middle, and top. Check whether the value changes smoothly and reaches both ends.

For a useful comparison, test the pedal without other MIDI controls in use. A keyboard's modulation wheel or another pedal could generate messages at the same time and make it harder to identify which input is changing.

What the result means

You see CC 1 and its value changes

CC 1 is the standard MIDI continuous controller number commonly used for modulation wheel data. If its value changes as you move the foot pedal, the pedal or its connected controller is sending modulation messages. The receiving instrument or software still needs to use CC 1 for the sound to change.

You see CC 11 instead

CC 11 is commonly used for expression. The pedal is sending MIDI, but it is not sending the usual modulation controller number. If you need it to act like a modulation wheel, look for a controller assignment in the keyboard or pedal's configuration options and set the pedal to CC 1, if that device allows it.

You see a different controller number

The pedal is working as a MIDI input, but it is assigned to another control. Check the device's configuration or the receiving instrument's MIDI mapping. Some pedals are designed to control volume or expression by default, and not every pedal can be reassigned on its own.

The value changes from 0 to 127

This is the usual full range for a MIDI control-change value. A pedal can still work if it only reaches part of that range, but the receiving instrument will have less control range to use. Compare the resting and fully pressed values, rather than expecting every pedal to behave identically.

No messages appear

The browser is not receiving input from the selected device. The pedal might not be connected through a MIDI device, the input could be wrong, or the browser may not have access. A passive pedal plugged into a keyboard's pedal jack does not necessarily appear as a separate MIDI input. The keyboard must translate its movement into MIDI messages.

You see notes or pitch bend, not a control change

The pedal or connected controller is sending a different kind of MIDI message. A modulation wheel is usually represented by CC 1, not by a note message. Check the device's assignment and the receiving software's expected message type.

How to fix missing or unexpected messages

1. Select the connected MIDI input. If the keyboard and another MIDI device are both listed, select the keyboard or controller the pedal is connected to, then move the pedal again.
2. Reconnect the device. Unplug and reconnect the keyboard or MIDI interface, then check the input list again. If you connected the device after opening the test, reload the page and select it again.
3. Check browser support. MIDI Test does not work in Safari. Open the page in a browser with Web MIDI support, then allow access if the browser asks.
4. Check the pedal connection. Make sure the pedal is plugged into the correct jack on the keyboard or controller. Some keyboards have separate jacks for sustain and expression pedals, and may respond differently to each.
5. Check the controller assignment. Use the keyboard or pedal maker's configuration options to assign CC 1 if modulation is what you need. The pedal may otherwise send CC 11 for expression, or a different control number.
6. Check the receiving instrument. Set its MIDI mapping to respond to the controller number shown in the test. If it expects CC 1 but the pedal sends CC 11, the pedal can appear functional while modulation remains unchanged.
7. Test another cable, port, or device. If no messages arrive, connect the keyboard directly to another USB port or test it with another computer. This helps separate a pedal problem from a keyboard, interface, or cable problem.

When the pedal or controller may be faulty

If the keyboard receives no pedal input in MIDI Test and the same result occurs with a known working cable or another computer, the pedal, jack, or controller may be damaged. If the message appears but the value jumps, stalls, or changes without you moving the pedal, try the pedal with another compatible controller. A fault that follows the pedal points to the pedal itself; one that stays with a particular jack points to the keyboard or controller.

For a warranty claim, note the MIDI input used, the controller number, and the values seen at rest and at full travel. A browser test can show what messages reach the computer, but it cannot identify which internal component has failed.

Modulation and expression are different controls

A modulation wheel commonly sends CC 1, while an expression pedal commonly sends CC 11. Both can send values that change as you move them, so a changing number alone does not prove the pedal is sending modulation. Check the controller number as well as the value.

A pedal's physical movement also may not match the full MIDI range. Its design, calibration, and the connected controller can affect the values it sends. If messages arrive consistently but cover only part of the range, check whether the device has a calibration option before treating the pedal as defective.