Comtech EF Data SDM-650B - Manual (Page 312)

Trojan Interface SDM-650B Satellite Modem
G–16 Rev. 5
G.6 Remote Control Operation
This section describes the remote control operation of the SDM-650B with the Trojan
interface installed.
• Firmware number: FW/0713-70A
• Software version: 4.13T
G.6.1 General
Remote controls and status information are transferred via an RS-485 (optional RS-232-C)
serial communications link.
Commands and data are transferred on the remote control communications link as
US ASCII-encoded character strings.
The remote communications link is operated in a half-duplex mode. Communications on the
remote link are initiated by a remote controller or terminal.
The modem never transmits data on the link unless it is commanded to do so.
G.6.1.1 Message Structure
The ASCII character format used requires 11 bits/character:
• 1 start bit
• 7 information bits
• 1 parity bit (odd/even)
• 2 stop bits
Messages on the remote link fall into the categories of commands and responses.
Commands are messages which are transmitted to a satellite modem, while responses are
messages returned by a satellite modem in response to a command.
The general message structure is as follows:
• Start Character
• Device Address
• Command/Response
• End of Message Character