Epson GT-6500 EN - Manual (Page 130)

Image Definition Commands
ESC L Set brightness
Format: B2 B3 B4 B5 A5
Command: ASCII: ESC L
Decimal: 27 76
Hexadecimal: 1B 4C
Parameter: i
Handshaking:
1 ESC L command
2 ACK code
3 Parameter (i)
4 ACK code
3-36 Command Reference