Remote Commands And Queries Overview; Basic Protocol - Comtec CDM-840 Installation And Operation Manual

CDM-840 Remote Router
Serial-based Remote Product Management
CDM-840 Serial Remote Product Management is available through the EIA-232 operational interface, where the 'Controller' device (the
user PC or an ASCII dumb terminal) is connected directly to the 'Target' device (the CDM-840, via its DB-9M 'CONSOLE' port). This
connection makes possible serial remote monitor and control (M&C) of the system through its CDM-840 Serial Interface.
Through this EIA-232 connection (for the control of a single device), 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 later in this chapter.
Access to the interface is accomplished with a user-supplied terminal emulator program such as Tera Term or HyperTerminal. Use this
utility program to first configure serial port communication and terminal display operation:
• 38400 bps (Baud Rate)
•
Parity=NO
When the user-supplied terminal emulator program is configured correctly, upon power-up of the system, the COMTECH EF DATA
CDM-840 SERIAL INTERFACE Info Screen appears, followed by the CDM-840> command prompt. From here, type "help[cr]" or "?[cr]"
(without the quotes) to display the available "set" commands and "get" queries, and to review instructions for using the interface.
7.2

Remote Commands and Queries Overview

7.2.1

Basic Protocol

In an EIA-232 configuration, the Controller device is connected directly to the Target device via a two wire-plus-ground connection. 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). 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:
•
Controller-to-Target: The Controller device (e.g., the user PC/Serial Interface) is used to "set", or transmit, instructions
(commands) to – or to "get", or request, information from (queries) – the Target device (i.e., the CDM-800).
• Target-to-Controller: The Target, in return, only transmits response information to the Controller when specifically directed by the
Controller.
• 8 Data Bits
•
Port Flow Control=NONE
7–3
• 1 Stop Bit
•
Display New line Rx/Tx: CR
MN-CDM840
Revision 3
• Local Echo=ON