MIDI Monitor Knowledge Base Guide

Overview

MIDI Monitor is a web-based utility by Morningstar Engineering that allows users to view incoming and outgoing MIDI messages in real time. It is designed for troubleshooting MIDI devices, debugging MIDI workflows, and verifying MIDI communication between controllers, pedals, DAWs, and other MIDI-enabled hardware.

Website: MIDI Monitor

What is MIDI?

MIDI (Musical Instrument Digital Interface) is a communication standard used by electronic musical instruments, controllers, computers, and audio devices. MIDI messages contain performance and control data such as:

• Note On / Note Off
• Control Change (CC)
• Program Change
• Pitch Bend
• Aftertouch
• System Exclusive (SysEx)

A MIDI monitor helps visualize these messages so users can diagnose configuration problems or confirm that devices are transmitting the correct data.

Main Features

Real-Time MIDI Monitoring

MIDI Monitor displays MIDI data as it is received from connected devices. Messages appear in a scrolling log with information such as:

• Timestamp
• Device name
• MIDI message type
• MIDI channel
• Data bytes

This makes it easy to verify whether a device is sending the expected MIDI commands.

Device Selection

Users can choose which MIDI devices to monitor.

Available controls include:

• Refresh device list
• Select all devices
• Deselect all devices

This is useful when multiple MIDI devices are connected simultaneously.

Message Type Filtering

MIDI Monitor allows filtering by MIDI message type so users can focus only on relevant data.

Supported message types include:

• Note On
• Note Off
• Polyphonic Aftertouch
• Control Change (CC)
• Program Change
• Channel Aftertouch
• Pitch Bend
• System Exclusive (SysEx)
• System Common
• System Realtime
• Unknown

Filtering reduces clutter and simplifies troubleshooting.

MIDI Channel Filtering

Users can filter messages by MIDI channel (1–16).

This is especially useful when:

• Multiple devices share the same MIDI connection
• A controller transmits on specific channels
• Troubleshooting channel mismatch issues

Start / Stop Monitoring

Monitoring can be started or stopped at any time.

When stopped:

• Incoming messages are ignored
• Existing logs remain visible

When started again:

• New messages continue appearing in real time

Clear Message Log

The Clear button removes all currently displayed MIDI messages without disconnecting devices.

Useful during testing workflows where users want to isolate a specific action or event.

Web-Based Operation

MIDI Monitor runs directly in the browser using the Web MIDI API.

Advantages include:

• No installation required
• Cross-platform compatibility
• Fast access from any supported browser

Modern Chromium-based browsers such as Chrome and Edge provide the best compatibility for Web MIDI functionality. (MIDI Monitor)

Common Use Cases

Verifying MIDI Controller Output

Users can confirm that a MIDI controller sends the correct:

• CC numbers
• Program Changes
• Note messages
• Expression pedal values

Example:

Pressing a footswitch should generate:

Control Change
CC#20
Value 127
Channel 1

Troubleshooting MIDI Connections

MIDI Monitor helps identify:

• Incorrect MIDI channels
• Missing messages
• Duplicate MIDI events
• Stuck notes
• Unexpected SysEx data

Testing Morningstar Controllers

MIDI Monitor is particularly useful when configuring:

• MC6 Pro
• MC8
• ML10X
• MIDI interfaces
• External MIDI pedals

Users can validate Morningstar preset actions and MIDI routing behavior in real time.

Monitoring SysEx Messages

Advanced users can inspect SysEx communication for:

• Firmware updates
• Device configuration
• Backup/restore operations
• Proprietary MIDI protocols

Understanding MIDI Message Types

Note On / Note Off

Used for keyboard and note-trigger events.

Example:

Note On
Channel 1
Note C3
Velocity 100

Control Change (CC)

Used for parameter control such as:

• Expression pedals
• Knobs
• Switches

Common examples:

Program Change

Changes presets or patches on connected devices.

Example:

Program Change
Program 12
Channel 3

Pitch Bend

Provides continuous pitch modulation.

Unlike CC messages, Pitch Bend uses higher-resolution data for smoother transitions.

System Exclusive (SysEx)

Manufacturer-specific MIDI data used for:

• Device configuration
• Firmware communication
• Preset transfer

SysEx messages can be significantly longer than standard MIDI messages.

Browser Permissions

Because MIDI Monitor uses the Web MIDI API, browsers may request permission to access MIDI devices.

If devices do not appear:

1. Ensure the browser supports Web MIDI
2. Grant MIDI permissions
3. Reconnect the device
4. Refresh the page

Troubleshooting

No MIDI Devices Detected

Possible causes:

• Browser does not support Web MIDI
• Device is not connected
• Device drivers are missing
• Another application is already using the MIDI port

No Messages Appearing

Check:

• Correct device is selected
• Monitoring is started
• MIDI channel filter is correct
• Device is transmitting MIDI

Duplicate MIDI Messages

Possible causes include:

• MIDI loopback routing
• Multiple MIDI paths
• DAW MIDI echo enabled

Best Practices

• Filter message types during troubleshooting
• Clear logs before testing
• Test one device at a time when diagnosing issues
• Use channel filters for complex MIDI rigs
• Keep firmware updated on connected devices

Additional Resources

MIDI Specifications

The MIDI Association:

MIDI Association Official Website

Other MIDI Monitoring Tools

Examples of desktop MIDI monitoring applications include:

• Snoize MIDI Monitor (macOS) (Snoize)

Summary

MIDI Monitor is a lightweight and powerful browser-based tool for inspecting MIDI communication in real time. It provides essential functionality for musicians, developers, and MIDI enthusiasts who need to debug, verify, or understand MIDI data flows.

Updated on: 18/05/2026