SYSEX messages are usually found in the manual for the device (your SD2).
PT can send SYSEX messages if you enter them, but the manufacturer usually defines the values.

Search the SD2 PDF below for 'Attack' .. hope it helps; seems to define Attack parameters. (CTRL + F in browser worked for me to search it)

NRPN 0163H BnH 63H 01H 62H 63H 06H vv Env. attack time modify (vv=40H no modify)

https://www.bhphotovideo.com/lit_files/87401.pdf



Make your sound your own!
.. I do not work here, but the benefits are still awesome