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3 basic protocol, 4 packet structure – Comtech EF Data MBT-4000B User Manual

Page 55

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MBT-4000B Multi-band Transceiver System

Revision 1

Serial-based Remote Product Management

MN/MBT4000B.IOM

6–3

6.2.3 Basic Protocol

Whether in EIA-232 or EIA-485 mode, all data is transmitted as asynchronous serial characters, suitable for transmission and reception

by a UART. The character format should be 8N1 (8 data bits, no parity, 1 stop bit). The baud rate may vary from 2400 to 38400 baud.

All data is transmitted in framed packets. The Controller is assumed to be a PC or ASCII dumb terminal, which 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 EIA-485 mode.

6.2.4 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)

0-9

ASCII codes 48-57

(4 characters)

/

ASCII code 47

(1 character)

A-Z, a-z

ASCII codes 65-90,

97-122

(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)

0-9

ASCII codes 48-57

(4 characters)

/

ASCII code 47

(1 character)

A-Z, a-z

ASCII codes 65-90,

97-122

(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=1{CR}{LF}