Section 5
Sensor Communication
26
FT702LT Flat Front Wind Sensor Manual
5 SENSOR COMMUNICATION
5.1 Introduction
The FT702LT features an easy to use ASCII-based communication protocol transmitted over an RS485 serial
link. The protocol incorporates checksum validation to ensure the integrity of all data transmissions.
In addition to the FT Technologies proprietary protocol the FT702LT can output the common NMEA 0183 MWV
(Wind Speed and Angle) sentence.
5.2 Configuring the FT702LT
All user parameter settings are stored in non-volatile memory and are retained when the FT702LT is switched
off. When the FT702LT is next switched on (or a user reset command is sent) the FT702LT will revert to these
settings. The FT702LT can therefore be configured as required prior to final installation if required.
The FT702LT settings can be returned to the factory values (see Figure 27 for factory default settings) at any
time by sending the factory reset command.
5.3 Communication
5.3.1
Conventions used in this manual
All examples of FT702LT transmitted and received messages are printed in italic courier monospace font, e.g.
$<listenerID>,DFP*<checksum><cr><lf>
Angle brackets are used as placeholders for data (e.g. <wind speed>) or for non-printable ASCII characters
(e.g. <cr> for carriage return).
Figure 23 lists the various special characters and symbols which are used in the examples given in this
Handbook.
Symbol
Valid Characters
HEX Values
Definition
a
{A to Z} {0 to 9} {/}
41-5A, 30-39, 2F
talker/listener address field characters
c
{A to Z} {0 to 9}
41-5A, 30-39
fixed length field of alpha (upper case only) and
numeric characters
h
{A to F} {0 to 9} {/}
30-39, 41-46, 2F
checksum field validation characters
s
{ }
20
space
x
0 to 9
30-39
fixed length field of numeric characters
x.x
{0 to 9} {.}
30-39, 2E
fixed point numeric field (i.e. always with leading
and trailing zeros)
{+ -}
2B, 2D
polarity indicator. Where a value can take on both
positive and negative values a polarity indicator
( or -) is always sent as the first character
in the field. The field length therefore remains
fixed for both positive and negative values.
{$}
24
start of message delimiter
{*}
2A
checksum field delimiter
{,}
2C
field delimiter
-
{-}
2D
dash
<cr>
0D
Carriage return
Line feed
<lf>
0A
<name>
placeholder for data
Figure 23: Symbols used in this Handbook
End of message
delimiter
