Registered Parameter Number (RPN)

Number: 101 (coarse) 100 (fine)

Affects:

Which parameter the Data Button Increment, Data Button Decrement, or Data Entry controllers affect. Since RPN has a coarse/fine pair (14-bit), the number of parameters that can be registered is 16,384. That's a lot of parameters that a MIDI device could allow to be controlled over MIDI. It's up to the MMA to assign Registered Parameter Numbers to specific functions.

Value Range:

0 to 16,384 where each value stands for a different RPN. Here are the currently registered parameter numbers:

Pitch Bend Range (ie, Sensitivity) 0x0000

Note: The coarse adjustment (usually set via Data Entry 6) sets the range in semitones. The fine adjustment (usually set via Data Entry 38) set the range in cents. For example, to adjust the pitch wheel range to go up/down 2 semitones and 4 cents: 

B0 65 00  Controller/chan 0, RPN coarse (101), Pitch Bend Range
B0 64 00  Controller/chan 0, RPN fine (100), Pitch Bend Range
B0 06 02  Controller/chan 0, Data Entry coarse, +/- 2 semitones
B0 26 04  Controller/chan 0, Data Entry fine, +/- 4 cents
Master Fine Tuning (ie, in cents) 0x0001

Note: Both the coarse and fine adjustments together form a 14-bit value that sets the tuning in semitones, where 0x2000 is A440 tuning.

Master Coarse Tuning (in half-steps) 0x0002

Note: Setting the coarse adjustment adjusts the tuning in semitones, where 0x40 is A440 tuning. There is no need to set a fine adjustment.

RPN Reset 0x3FFF

Note: No coarse or fine adjustments are applicable. This is a "dummy" parameter.

Here's the way that you use RPN. First, you decide which RPN you wish to control. Let's say that we wish to set Master Fine Tuning on a device. That's RPN 0x0001. We need to send the device the RPN Coarse and RPN Fine controller messages in order to tell it to affect RPN 0x0001. So, we divide the 0x0001 into 2 bytes, the fine byte and the coarse byte. The fine byte contains bits 0 to 6 of the 14-bit value. The coarse byte contains bits 7 to 13 of the 14-bit value, right-justified. So, here are the RPN Coarse and Fine messages (assuming that the device is responding to MIDI channel 0): 

B0 65 00  Controller/chan 0, RPN coarse (101), bits
	    7 to 13 of 0x0001, right-justified (with high bit clear)
B0 64 01  Controller/chan 0, RPN fine (100), bits
	    0 to 6 of 0x0001, (with high bit clear)
Now, we've just told the device that any Data Button Increment, Data Button decrement, or Data Entry controllers it receives should affect the Master Fine Tuning. Let's say that we wish to set this tuning to the 14-bit value 0x2000 (which happens to be centered tuning). We could use the Data Entry (coarse and fine) controller messages as so to send that 0x2000: 
B0 06 40  Controller/chan 0, Data Entry coarse (6), bits
	    7 to 13 of 0x2000, right-justified (with high bit clear)
B0 26 00  Controller/chan 0, Data Entry fine (38), bits
	    0 to 6 of 0x2000, (with high bit clear)
As a final example, let's say that we wish to increment the Master Fine Tuning by one (ie, to 0x2001). We could use the Data Entry messages again. Or, we could use the Data Button Increment, which doesn't have a coarse/fine pair of controller numbers like Data Entry. 
B0 60 00  Controller/chan 0, Data Button Increment (96),
               last byte is unused
Of course, if the device receives RPN messages for another parameter, then the Data Button Increment, Data Button Decrement, and Data Entry controllers will switch to adjusting that parameter.

RPN 0x3FFF (reset) forces the Data Button increment, Data Button decrement, and Data Entry controllers to not adjust any RPN (ie, disables those buttons' adjustment of any RPN).