Comtech EF Data SMS-458B - Manual (Page 109)

B–1
Appendix B. REMOTE
OPERATION
This appendix describes remote control specification of the SMS-458B Switch:
• Firmware number:
FW/0713-85
• Version number:
4.00
B.1 General
Remote controls and status information are transferred via an EIA-485 (optional
EIA-232) 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. A remote controller or terminal
initiates communications on the remote link. The switch never transmits data on the link,
unless it is commanded to do so.
B.2 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 switch, while responses are
messages returned by a satellite switch in response to a command.