EMM Labs PRE2-SE - Manual (Page 21)

021 Appendix A - PRE2 Serial Remote Control (RS232)
© 2014 EMM Labs Inc., All Rights Reserved. EMM Labs reserves the right to amend specifications & design without notice.
PRE2 STEREO PREAMPLIFIER OWNER’S MANUAL
PRE2 Serial Remote Control (RS232)
Frame Structure (cont’d)
Checksum : C1, C0 one-byte checksum, its binary value represented by 2 hex characters, or, the
opt-out variant, where the checksum is substituted by "NA" token, as in 'Not-A-checksum' or
'Not Applicable'. The checksum is calculated as byte-wide exclusive OR from all preceding
characters in the frame, excluding frame preamble (the asterisk). Checksum seed value is
0x00. Character ASCII codes are used in the calculation.
Command Message Structure
The Command Message for PRE2 is four character long (M3, M2, M1, and M0) and is composed of two parts:
Command Code : C1, C2 two alphanumeric characters and/or decimal digits (A-Z, a-z, 0-9)
Parameter Value : V1, V2 one-byte value represented by 2 hex digits (0-9, A-F).
Control Messages
Complete message frames are shown, and the blank checksum (the “NA”) is used.
Volume (VL) : *PRVLxxNA where ‘xx’ is volume step number (0 to 100) formatted as 2 hexadecimal digits.
Examples: step number 10 will be encoded as ‘0A’ or step number 100 will be encoded as ‘64’.
Select Input (SI) : *PRSI0iNA where 'i' is the input number, encoded as a character '1' to '6'
Mute (MT) : *PRMT00NA mute OFF
*PRMT01NA soft mute
*PRMT02NA mute ON