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REMOTE CONTROL OPERATION:
This appendix defines the protocol and command structure for the "modem switch" style
of remote control and status monitoring of the EFData SMS-758 switch. With modem
switch software, when the switch detects either a modulator or demodulator failure on
the prime modem, both the modulator and demodulator functions will be switched to the
backup modem.
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A.1 General
Remote controls and status information are transferred via an RS-485 (optional RS-232C)
serial communications link. For RS-232C communication, switch SP1-5 on the M&C
module must be turned ON.
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 switch never transmits data on the link unless it is commanded to do so.
A.2 Message Structure
The ASCII character format used requires 11 bits/character:
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MN/SMS758 Rev. 3
Firmware number:
FW/0713-33J
Software version:
5.10
1 start bit
7 information bits
1 parity bit (odd/even)
2 stop bits
Appendix A.
MODEM SWITCH
A–1
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