Comtech EF Data HPCST-5000 - Manual (Page 150)

Programming Guide for Redundant Controller High-Power TWTA Satellite Terminals
A–2 Rev. 1
Redundant systems include two serial-interface communications channels (RS-232-C and
RS-485) that are available for remote control use at any time. Concurrent commands on
both channels are acknowledged on each channel as they are received. The last command
received has precedence. Any conflict between commands sent via the two serial
interfaces is resolved in favor of the last command received.
When the system is set for REMOTE operation, remote “query” commands and remote
“control” commands are accepted by the system. When the system is setup for LOCAL
operation, remote “query” commands only are accepted and remote “control” commands
are ignored.
Note: For LOCAL operation procedures and details, refer to Chapter 6 for the redundant
controller supplied with the redundant system.
Section A.2 of this guide discusses the communication protocols.
Section A.3 discusses the redundant system command set.
Section A.4 presents the TWTA command set.
A.1.1 Communication Protocols
Serial communications with the system controller is achieved using two message
formats:
•
Command message format
•
Response message format
The system controller is assigned a unique address (Primary Address Byte). The
procedure for assigning the primary address is discussed in Chapter 6. The default
primary address is the ASCII character “Z”. The TWTAs are identified as “A”, “B”, etc.
(secondary address byte). Each TWTA is hard-wired (interface cable) to the redundant
controller. The system controller decodes the secondary address to forward the TWTA
commands to the proper TWTA. The command links between the system controller and
each TWTA is via an RS-232-C serial interface.