Let's see if I can get you started.
Normally when you want to create a Midi Designer (MD) layout you need to find out if your synth accepts midi CC, midi sysex or NRPNs. Most often any synth will have a few standard midi CC messages it responds to and then it can be either sysex or NRPNs.
If it's sysex you need to find the paramater change sysex command. If the manufacturer isn't lazy you will find a midi specification in your manual.
If you have a DX27 manual, page 48 contains the parameter change sysex command.
The parameter change sysex command is
F0 43 10 12
The third value 10 is only 10 if your synth is set to midi channel 1. If your synth is set to midi channel 2 the value will be 11 instead of 10. Midi channel 3 will result in value 12 etc etc. I recommend for the time being to keep your midi channel on your synth to 1. So in this case your sysex command is
F0 43 10 12
Fortunately Midi Designer doesn't need the F0 so that one is ommitted.
Your sysex string results in
43 10 12
This is just the first part. Now you have to define the parameter you want to change and the data you want to send.
Say, you want to control the Algorithm Select.
On page 55 the parameter number for Algorithm Select is 52.
However, this is a decimal value and should be changed to a hexadecimal value. If you don't know about hex use the Midi Byte Calculator.
http://mididesigner.com/help/midi-byte-calculator/?sum=12&number_of_bytes=1
Enter 52 in the Value To Bytes field and press Submit Query button.
The result will appear in the Bytes To Value field.
The result is 34.
So now you know the parameter number.
Your parameter change sysex command for Algorithm Select is now :
43 10 12 34
However, Midi Designer also expects a value that your knob will send when you turn it. You will always enter V for that value.
This results in your final sysex command string.
43 10 12 34 V
Now comes the Midi Designer part.
- You create a knob in Midi Designer.
- Double tap the knob to get its properties screen.
- Go to the Midi tab.
- Choose Message Type to be sysex
- Now enter the resulting string I described above
43 10 12 34 V
- Press apply.
- Set midi min and midi max of your knob.
- Done.
- Now make sure in your DX27 Midi Sys Info is set to on otherwise your DX27 will not receive the command.
- Now test your knob.
If it works you can continue with the rest of the knobs and buttons.
Now it gets more simple. You only need to copy the sysex command string and substitute the parameter number (the value before the V)
43 10 12 34 V
Let me know how it goes.