Line 6 AX2 212 MIDI Specification
The AX2 212 MIDI interface allows control over program and bank selection, the use of controllers for wah, volume, and modulation, and system exclusive commands for editing and program dumps. Since the AX2 212 is not a sound generator, status messages for note off (8xH), note on (9xH), poly pressure (AxH), channel pressure (DxH), and pitch bend (ExH) are ignored when received, and never transmitted. Controllers (BxH) and program change commands (CxH) are received and transmitted on the MIDI channel set by the user (or modified via MIDI by using sysex commands). If the MIDI channel is set to omni, the AX2 212 will receive commands on all channels, and transmit on channel 1. For additional information on the specific parameters and features of the AX2 212, please refer to the AX2 212 User Manual.
Volume control
The volume control of the AX2 212 is transmitted as controller 7 any time the volume footpedal is moved. The volume can be controlled via MIDI with either controller number 7 or 11 (both are always received). Note that if the current program is set with the volume pedal disabled, the MIDI controller changes will have no affect.
Wah control
The wah control of the AX2 212 is transmitted as controller 4 any time the wah footpedal is moved. The wah can be controlled via MIDI with either controller number 3 or 4 (both are always received). Note that if the current program is set with the wah pedal disabled, or to a non-pedal controlled wah such as auto-wah, the MIDI controller changes will have no affect. The user can also set the wah pedal to control any one of most of the parameters instead of functioning as a wah. MIDI control of the selected parameter is then also possible, via controller 3 or 4.
Bank Select
The AX2 212 will respond to controller 0 or 32 as a bank select command. It will take the least significant bit of either controller value, and use it to select a program bank. If the bit is 0, the preset bank is selected. If the bit is 1, the user bank is selected. The change does not take affect until a program change command is received. Bank select commands are not transmitted from the AX2 212.
Program Change
The AX2 212 responds to program change values of 0 to 127, and selects the appropriate program from the current program bank. The AX2 212’s programs are organized as 32 sets (called Sound Banks, and numbered 01 through 32) of 4 programs (called Sounds A, B, C, and D). MIDI program number 0 relates to program 01A, MIDI program number 1 selects program 01B, and so on. MIDI program number 127 will select program 32D. The AX2 212 will transmit a program change command any time the user selects a new program from the front panel or the Floor Board foot controller. Note: The user can select one received program number to be specified as a tuner
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select command, so that the tuner can be turned on via a MIDI program command. This can also be edited via MIDI sysex control of the global parameters, described later.
Universal System Inquiry
The AX2 212 will respond to the universal system inquiry command if the channel received is the same as the AX2 212’s MIDI channel, the channel received is 7F (all channels), or the AX2 212 is set to omni mode. The received message is in the following format:
F0 7E <chan> 06 01 F7 |
System inquiry message |
If the channel received is 7F, the AX2 212 will respond with the channel also set to 7F. If the channel received is not 7F, the AX2 212’s response will contain the same channel as was received. The response transmitted from the AX2 212 is in the following format:
F0 7E <chan> 06 02 |
System inquiry response |
00 01 0C |
Line 6 manufacturer's ID |
00 00 |
AX2 212 product family code |
00 00 |
AX2 212 device family member code |
xx xx xx xx |
Software version number (ASCII) |
F7 |
End of system exclusive |
The software version is a four digit ASCII code, with an assumed decimal point between the second and third digit. For example, version 1.05 would be represented by 30H 31H 30H 35H. Note: All received universal system commands are ignored while the AX2 212 is in tuner mode.
System Exclusive
System exclusive commands are used for sending and receiving programs, global settings, and for editing specific parameters. All transmitted and received sysex commands contain the same first five bytes:
F0 |
Sysex command |
|
00 |
Line 6 |
ID msb |
01 |
Line 6 |
ID mid |
0C |
Line 6 |
ID lsb |
00 |
AX2 212 ID |
|
The next byte (sixth byte) contains the opcode for the desired sysex command. There are currently six opcodes supported, and they are summarized here along with their data format:
00 Program dump
<program #> <83 bytes program data...> F7 01 Edit buffer dump
00 <83 bytes program data...> F7
02 Global buffer dump
<48 bytes global data...> F7
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03 Sysex dump request
<type> {<program #>} F7
{} may be omitted depending on type:
<type>=0 (program), <program #>=0..127 <type>=1 (edit buffer), no <program #> <type>=2 (global data), no <program #> <type>=3 (all programs), no <program #> (responds with 128 programs + global data)
04 Parameter edit
[<parameter #> <dataLSNibble> <dataMSNibble>] F7 Data in [...] can be repeated
05 Store edit buffer <program #> F7
Note: All received universal system commands are ignored while the AX2 212 is in tuner mode.
Program and Editing Formats
When sending or receiving a program or edit dump, the data is packed in the following format so as to minimize the amount of bytes required to transmit the program. For each 7 consecutive bytes of a program (labeled a through g below), 8 MIDI bytes are sent, as follows:
|
|
|
Bit # |
|
|
|
|
|
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
Byte |
00 |
a7 |
a6 |
a5 |
a4 |
a3 |
a2 |
a1 |
Byte 0 |
00 |
a0 |
b7 |
b6 |
b5 |
b4 |
b3 |
b2 |
Byte 1 |
00 |
b1 |
b0 |
c7 |
c6 |
c5 |
c4 |
c3 |
Byte 2 |
00 |
c2 |
c1 |
c0 |
d7 |
d6 |
d5 |
d4 |
Byte 3 |
00 |
d3 |
d2 |
d1 |
d0 |
e7 |
e6 |
e5 |
Byte 4 |
00 |
e4 |
e3 |
e2 |
e1 |
e0 |
f7 |
f6 |
Byte 5 |
00 |
f5 |
f4 |
f3 |
f2 |
f1 |
f0 |
g7 |
Byte 6 |
00 |
g6 |
g5 |
g4 |
g3 |
g2 |
g1 |
g0 |
Byte 7 |
Since there are a total of 72 bytes per program (prior to this packing format), 83 bytes of data are required to be sent out MIDI once converted to this format. When combined with the sysex header and EOX, the total number of bytes transmitted per program is 91 bytes.
All parameters are stored as 8-bit values. If the parameter range allows negative numbers, the parameters is stored as a 2’s compliment 8-bit number. There are 72 bytes stored with each program, each byte representing one parameter. The first 66 bytes relate to the 11 rows of six parameters, in order, starting from the top left-most parameter as printed on the AX2 212 front panel. For simplicity, the last two parameters of the first two rows (MIDI Channel, Transmit Sounds, Gate/Hum Per Sound, Aux Per Sound) are stored with each program, although they are global parameters and the value stored (or received) within each program will be ignored. The last six bytes of each program are spare and are reserved for future use. They should be left unchanged. Currently, the last three bytes of these six are used to represent the
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