We entered sysex data request 1 (rq1) scene common in MIDI Debugger and pressed Send to read a JUNO-D scene setting. The synth returned 63 bytes. The detail view identified the reply as “Temporary Scene / Scene Common”.
MIDI Debugger combines message input, sending and response inspection in one screen. Sent and received messages appear in the same list. CLI completion and message decoding use the device definitions shared with the monitor.
CLI input and completion
At the bottom of the screen are the destination, the channel, the input field (CLI) and a HEX field. In the input field you write a message as a short command:
note on C4 100
cc 74 96 ch2
nrpn 0:36 8
sysex data request 1 (rq1) scene commonThe commands are note, cc, pc, pb, cp, pp, rpn, nrpn, sysex, panic and reset. As you type, candidates appear just above the input field. Tab or a click accepts one, and choosing a candidate never sends anything.
The candidates come from the device definition assigned to the destination:
- Note names and values. Notes can be typed as names from C-1 to G9 (C4 = 60), and values accept
min,centerandmax. - CC, RPN and NRPN names. You can type the names from the definition, and plain numbers still work.
- SysEx. Besides the common messages, the destination’s own messages and the areas and blocks of its address map appear. In the screenshot, the JUNO-D’s scene areas are listed with their addresses and sizes.
Once the input forms a complete message, its bytes appear in the HEX field below. You can also write bytes directly in the HEX field and send them.
How sending works
Pressing Send sends the message. An NRPN becomes four CCs and a long SysEx several packets, but either way it is accepted as one action, all together. If it cannot be accepted, because of an input error or a problem with the destination, nothing is sent rather than only part of it. The app calculates the Roland checksum automatically according to the device definition.
A Tx row records an observed send, rather than merely an accepted send request. A response from the device appears separately as Rx. Input errors and send failures are reported in a dialog.
Inspecting the received SysEx
The DT1 detail view identifies areas and blocks. It does not decode the data into individual parameter values.
Messages you send and messages that arrive go into the same list, with columns for time, direction (Rx / Tx), source, type, channel, length and data. In the example above, the 17-byte RQ1 appears as Tx and the 63-byte DT1 as Rx right after it.
Selecting a row shows its contents in Message Detail on the right. For a DT1, that is the manufacturer, the model, the message type, the address and its name (“Temporary Scene / Scene Common”), and a hex dump of the whole message. The hex dump also shows the bytes as text, so here you can read the scene’s name, “Studio Piano”.
The monitor and MIDI Debugger share a decoder, so the same message has the same name in both.
Comparing messages and tracking values
- Compare. Select two messages in the list, and their bytes are lined up position by position, with differing bytes in red, along with the number and share of differences and the difference in length. It does not shift positions to look for inserted bytes.
- Watch. Register items such as CC 74 or Pitch Bend, and their latest value and time stay visible while the list scrolls on. If observations were lost, the value is shown as uncertain instead of being treated as known.
- Channel State. For the channel of the selected message, it shows the notes still held, Bank Select, Program, Pitch Bend, Sustain and other latest observed values. It shows only what was observed and does not guess the device’s state.
Recording and sending again
Record captures what goes to and from the devices you choose, and you can save it as a Take. Replay sends messages you pick from a recording again, to a destination you choose, either all at once or one at a time. You can, for example, send the same request again when no reply came.
Sending and inspecting on one screen
Investigating MIDI is a loop: send a message, check what comes back, change it a little, send again. When sending and watching are separate tools, you keep switching between them and matching what you sent with the replies yourself. The MIDI Debugger puts that loop on one screen.
Updating a device definition changes both completion and decoding in the monitor and MIDI Debugger. The definition format is described in How CC 102 became “OP1 Level”, and the JUNO-D address map in Sending and reading JUNO-D SysEx by name.