Denon DN-500AV Owner's Manual page 97

Communication protocol
The following three data forms are defined.
n COMMAND
The message sent to a system from a host.
A command to a system is given from a host. Refer to the following table for the contents of "Control
command code table" (vpage 93).
n RESPONSE
The message is sent to a host from a system if the 'request command' (COMMAND+?+CR(0x0D)) has
came from a host.
The RESPONSE should be sent within 200 ms of receiving the COMMAND.
The form of RESPONSE presupposes that it is the same as that of EVENT.
Refer to the following table for the contents of "Status request and status information code table"
(vpage 102).
n EVENT
The message sent to a host from a system.
The result is sent, when a system is operated directly and a state changes.
The form of EVENT presupposes that it is the same as that of COMMAND.
Refer to the following table for the contents of "Status request and status information code table" –
"Status information command and Status command" (vpage 102).
Basic specification
The command by ASCII CODE, parameter expression.
NOTE
ASCII CODE which can be used is from 0x20 to 0x7F: the alphabet and the number of 0 – 9, and space
(0x20), some signs, and carriage return (0x0D) --- It is used only as a pause sign.
BD
Structure of control commands
Each packet of a control command begins with the COMMAND and ends with the End Character "0x0D"
as shown below.
COMMAND
COMMAND
COMMAND: ASCII CODE of 2 characters
PARAMETER: ASCII CODE (up to 25 characters)
NOTE
To confirm the status information of the unit, send COMMAND + ? + CR to the unit from the host.
The unit status information is sent to the host.
For "Status request and status information code table" (vpage 102).
Structure of command codes
Item
COMMAND Indicate a description of the command.
PARAMETER Indicate a description of the parameter.
End Character 'CR'(0 x 0D)
The response time out is 200 msec.
• When a command is received, this unit responds within 200 msec.
• Allow an interval of at least 200 msec between commands when sending a series of commands from the
host. This unit will not receive commands when the interval is less than 200 msec.
• COMMAND is receivable also during transmission of EVENT.
• Do not send request commands from the host until this unit returns a RESPONSE.
• 1 seconds later, please transmit the next COMMAND after transmitting a power on COMMAND (PWON).
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End
PARAMETER
Character
CR (0x0D)
+ PARAMETER + CR (0x0D)
Value
(The hex value is indicated in parentheses)