Comtech EF Data SDM-309B - Manual (Page 178)

MN/U-SDM309B Rev. # B-B–1
Appendix B.
SATELLITE MODEM REMOTE
CONTROL
1.0 Scope
This document defines the protocol and command structure for remote control and status
monitoring of the EFData SDM308-5 satellite modem. Firmware FW/0713-60E, version
6.05.
2.0 General
Remote control and status information is transferred via a RS-485 (optional RS-232C)
serial communications link. Commands and data are transfered on the remote control
communications link as US ASCII encoded character strings. The remote
communications link is operated in a half duplex mode. Communcations on the remote
link are initiated by a remote controller or terminal. The SDM308-5 never transmits data
on the link unless it is commanded to do so.
3.0 Message Structure
The ASCII character format used requires 10 or 11 bits/character: 1 start bit, 7
information bits, 1 parity bit (odd/even), and 1 or 2 stop bits.
Messages on the remote link fall into the catagories of commands and responses.
Commands are messages which are transmit 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
“add”
! Command/Response
! End of Message Character