Comtech EF Data CDM-760, Installation And Operation Manual

Page: 378 / 441

Appendix G Revision 4
CDM-760 Advanced High-Speed Trunking Modem MN-CDM760
G–29
G.5.4 ACM Operation Using the CDM-760 Serial Remote Control Interface
G.5.4.1 CDM-760 Typical Serial Remote Control Overview
See Chapter 8. SERIAL INTERFACE OPERATION for an in-depth explanation of the
use of remote commands and queries over the CDM-760 Serial Remote Control
Interface.
The CDM-760’s serial remote interface is an electrical interface that is either an EIA-485 multi-
drop bus (for the control of multiple devices) or an EIA-232 connection (for the control of a
single device). The interface uses ASCII characters in asynchronous serial form to transmit data
between the Controller (e.g., a User PC) and Target (e.g., the modem and ODU). This data
consists of control and status information, transmitted in packets of variable length in
accordance with the structure and protocol explained in detail in Chapter 8.
The Controller is in charge of the process of monitor and control, and is the only device that is
permitted to initiate, at will, the transmission of data. Targets are only permitted to transmit
when they have been specifically instructed to do so by the Controller.
The exchange of information is transmitted, Controller-to-Target and Target-to-Controller, in
‘ packets ’. Each packet contains a finite number of bytes consisting of printable ASCII characters,
excluding ASCII code 127 (DELETE).
In this context, the Carriage Return and Line Feed characters are considered printable. With one
exception, all messages from Controller-to-Target require a response – this will be either to return
data that has been requested by the Controller, or to acknowledge reception of an instruction to
change the configuration of the Target.
Controller-to-Target (Issued Command or Query)
Start of Packet Target Address
Address
Delimiter
Instruction
Code
Code Qualifier
Optional
Arguments
End of Packet
<
ASCII Code 60
(1 character)
0000 (default)
(4 characters)
/
ASCII Code 47
(1 character) (3 characters)
= or ?
ASCII Codes 61
or 63
(1 character)
(n characters)
Carriage Return
ASCII Code 13
(1 character)
Packet “issued command” example: <0000/TMC = 10[cr]
Packet “issued query” example: <0000/TMC?[cr]
Target-to-Controller (Response to Command or Query)
Start of Packet Target Address
Address
Delimiter
Instruction
Code
Code Qualifier
Optional
Arguments
End of Packet
>
ASCII Code 62
(1 character)
0000 (default)
(4 characters)
/
ASCII Code 47
(1 character) (3 characters)
= , ?, !, *, #, ~
(ASCII Codes
61, 63, 33, 42,
35, or 126)
(1 character)
(n characters)
Carriage Return
ASCII Code 13
(1 character)
Packet example – response received for issued query: >0000/TMC = 10[cr][lf]