In some vehicle, a data of the Button Message needs to be increased every time it is sent.
The Button Message data indicated by Increasing Data Index is increased by Increment every time the Button Message is sent.
Increment can be -128 ~ 127.
If Increasing Data is not used, set 0 at Increasing Data Index .

Example:
Down Message is
Dur: 0 Len: 4 ID:0683 Data:04 00 20 0D
Up Message is
Dur: 0 Len: 4 ID:0683 Data:04 00 20 FF
Increasing Data Index is 2
Increment is 1

When the button is pressed and released, the messages are sent to the radio though BSGc like below.

S Len: 4 ID:0683 Data:04 09 20 FF
S Len: 4 ID:0683 Data:04 0A 20 0D
S Len: 4 ID:0683 Data:04 0B 20 FF
S Len: 4 ID:0683 Data:04 0C 20 0D
S Len: 4 ID:0683 Data:04 0D 20 FF
….