Mark Levinson 512 - Manual (Page 7)

Mark Levinson N o 512 CD/SACD Player Serial Communications Protocol
5 Message Formats and Examples
The external protocol consists of a structured format string with specific fields used to indicate:
ƒ Message type
ƒ Source of the command
ƒ Command
ƒ Status/Parameter
Messages can be transmitted to (incoming) and received from (outgoing) the N
o 512 to facilitate system
control via RS-232 or Ethernet connection.
5.1 Format of the Message Fields
All incoming and outgoing messages must use the following format:
HDR:SRC:CMD:PARAM\r
where:
HDR The Header field specifies the type of message:
RQST – incoming request
RSP – outgoing response
NTF – outgoing notification
SRC
The Source field specifies the source of the message:
CS – message from a Control Source
UI – message from a User Interaction
AV – used by notifications to indicate and event was caused by the component
without user interaction
CMD
The Command field specifies the command selected from the External Protocol
Commands table to invoke the desired functionality.
PARAM
The Parameter field specifies the selected parameter from the External Protocol
Commands table to achieve the desired effect.
Fields are separated by a colon “:” and messages are terminated with a ‘\r’ control character
(0x0d).
All fields, commands and associated parameters are case sensitive and must be entered as listed in the
External Protocol Commands table. Do not insert spaces in message sequences, unless they are
indicated in the table.
Maximum message size is 60 characters, including the line ending ASCII control character ‘\r’ (0x0D).
When an incoming or outgoing message uses more than one parameter, the individual parameters must
be separated by commas.
HDR:SRC:CMD:PARAM1,PARAM2,PARAM3,…\r
When an incoming command requires multiple parameters per request (RQST), ALL parameters for the
given command must be entered AND in the order presented in the External Protocol Commands table,
as the descriptors are not utilized in the parameter field of the command/response string. The response
message also follows these guidelines.
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