Appendix ap2 – EMM Labs PRE2-SE User Manual
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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)
Remote Control Protocol
The PRE2 Remote Control protocol is defined with the goal of structural simplicity and ease of implementation. Typical
implementation requires only a standard, asynchronous UART/RS232 port. At the Data Link level the following assumptions
are made:
• Short, fixed-length data frames
• Data encoding uses only ascii (printable) characters
• Data frame has a checksum field for error detection, but the checksum opt-out is possible at sender’s request - in such a
case, Sender’s frame has a standard blank checksum, and the Receiver side does not check against it.
At the Application level (i.e. remote control of a product) the message processing will be stateless:
• Each message is handled independently
• Each command acted upon immediately.
Frame Structure
The PRE2 frame structure is shown in the following diagram:
Frame preamble
:
<
> Asterisk character.
Destination Product Class :
P1, P0 two alphanumeric characters (a preamplifier product will be denoted as "PR").
Command Message
:
M3, M2, M1, M0 typically 4 characters long, but it is product-dependent.
| Product Class
*
P1
P0 M3 M2 M1 M0 C1 C0
| Command Message
| Cheksum |
*