Comtech EF Data MBT-4000 - Manual (Page 46)

MBT-4000 Multi-Band Transceiver System Revision 4
Remote Control MN/MBT4000.IOM
A–2
A.3 RS-232
This is a much simpler configuration in which the Controller device is connected directly to the
Target via a two-wire-plus-ground connection. Controller-to-Target data is carried, via RS-232
electrical levels, on one conductor, and Target-to-Controller data is carried in the other direction
on the other conductor.
A.4 Basic Protocol
Whether in RS-232 or RS-485 mode, all data is transmitted as asynchronous serial characters,
suitable for transmission and reception by a UART. The asynchronous character is fixed at 8-N-1
(8 data bits, no parity, one stop bit). Only two baud rates are supported: 9600 baud and 19200 baud.
All data is transmitted in framed packets. The Controller is assumed a PC or ASCII dumb
terminal that is in charge of the process of monitor and control. The Controller 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.
All bytes within a packet are printable ASCII characters, less than ASCII code 127. In this
context, the Carriage Return and Line Feed characters are considered printable.
All messages from Controller-to-Target require a response – with one exception: 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. The exception to this is when the Controller broadcasts a
message (such as Set Time/Date) using Address 0, when the Target is set to RS-485 mode.
A.5 Packet Structure
Controller-to-Target
Start of
Packet
Target
Address
Address
Delimiter
Instruction
Code
Code
Qualifier
Optional
Arguments
End of Packet
<
ASCII code 60
(1 character)
(4 or 6
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)
Example: <0412/MUT=1{CR}
Target-to-Controller
Start of
Packet
Target
Address
Address
Delimiter
Instruction
Code
Code
Qualifier
Optional
Arguments
End of Packet
>
ASCII code 62
(1 character)
(4 or 6
characters)
/
ASCII code 47
(1 character) (3 characters)
=, ?, !, or *
ASCII codes
61,63,33 or 42
(1 character)
(From 0 to n
characters)
Carriage Return,
Line Feed
ASCII codes
13,10
(2 characters)
Example: >0412/MUT={CR}{LF}