Appendix B. Remote Control; Overview; Basic Protocol - Comtech EF Data CDM-840 Installation And Operation Manual

B.1

Overview

This appendix describes the protocol and message command set for remote monitor and control (M&C) of the CDM-840 Remote Router.
The electrical interface is an EIA-232 connection (for the control of a single device), and data is transmitted in asynchronous serial form,
using ASCII characters. Control and status information is transmitted in packets of variable length in accordance with the structure and
protocol defined in later sections.
B.2 EIA-232
This is a configuration in which the 'Controller' device – assumed to be a PC or ASCII dumb terminal – is connected directly to the
'Target' device (i.e., the CDM-840 via its CONSOLE serial port) via a two wire-plus-ground connection. Controller-to-Target data is
carried via EIA-232 electrical levels on one conductor, and Target-to-Controller data is carried in the other direction on the other
conductor.
B.3

Basic Protocol

All data is transmitted in framed packets as asynchronous serial characters, suitable for transmission and reception to the Controller using
a universal asynchronous receiver/transmitter (UART). The character format should be 8N1 (eight data bits, no parity, one stop bit). The
baud rate is fixed at 38400 baud. Port flow control should be set to None.

Appendix B. REMOTE CONTROL

B–1