Comtech EF Data SDM-2020 - Manual (Page 202)

SDM-2020 Satellite Demodulator Revision 4
Remote Control Commands MN/SDM2020D.IOM
A–2
Commands are messages, which are transmitted to a satellite demodulator, while responses
are messages returned by a satellite demodulator in response to a command.
The general message structure is as follows:
• Start Character
• Device Address
• Command/Response
• End of Message Character
A.1.2 Start Character
A single character precedes all messages transmitted on the remote link. This character flags
the start of a message. This character is:
• “<” for commands
• “>” for responses
A.1.3 Device Address
The device address is the address of the one satellite demodulator which is designated to
receive a transmitted command, or which is responding to a command.
Valid device addresses are 1 to 3 characters long, and in the range of 1 to 255. Address 0 is
reserved as a global address, which simultaneously addresses all devices on a given
communications link. Devices do not acknowledge global commands.
Each satellite demodulator who is connected to a common remote communications link
must be assigned its own unique address.
A.1.4 End Character
Each message is ended with a single character, which signals the end of the message:
• “cr” Carriage return character for commands
• “]” End bracket for responses