Advent VISLINK Newswift 90 User Manual

VISLINK
Newswift 90-180 Motorised Antenna 27
4.59 PACKET PROTOCOL
(a) The general packet format is as follows
U:
[STX] [BYTE COUNT] [ADDRESS] [DATA....] [CHECKSUM] [ETX]
STX
The STX is one byte in size and always represents the start of a transmission. This byte is
always assigned the value 2
BYTE COUNT
The BYTE COUNT is one byte in size and is the total number of bytes in the packet, i.e.
number of data bytes plus five (one each for STX, BYTE COUNT, ADDRESS, CHECKSUM
and ETX).
ADDRESS
The ADDRESS is one byte in size. This is the address of the equipment to which the packet
is being sent. Unique addresses can be in the range 001 to 255. Note that 000 results in
global addressing
DATA
This is the actual data being sent to an equipment. In any one packet, the maximum number
of data bytes is 250.
CHECKSUM
The CHECKSUM is one byte in size and is included for error detection. It is the modulo
addition of all ADDRESS and DATA bytes. (See (b) below)
ETX
The ETX is one byte in size and always represents the end of a transmission. This byte is
always assigned the value 3.
(b)
UChecksum
Here is a typical example:
[STX] [BYTE COUNT] [ADDRESS] [DATA....] [CHECKSUM] [ETX]
[2] [8] [5] [97 98 99] [43] [3]
Checksum is calculated from CHKSUM = (5+97+98+99) mod 256, i.e. 43.

Advent VISLINK Newswift 90 Specifications

General

Brand	Advent
Model	VISLINK Newswift 90
Category	Marine GPS System
Language	English