Section 6
Sensor Communication
33
FT742-SM (RS422 & RS485) Sensors
– User Manual
6.3 Configuring the Sensor
All user parameter settings are stored in non-volatile memory and are retained when the sensor is switched off.
When the sensor is next switched on (or a user reset command is sent) the sensor will revert to these settings.
The sensor can therefore be configured prior to final installation if required.
The sensor settings can be returned to the factory values (see Figure 26 for factory default settings) at any time
by sending the factory reset command.
6.4 Communication
6.4.1
Conventions used in this manual
All examples of sensor transmitted and received messages are printed in italic courier monospace font, e.g.
$<listenerID>,DFP*<checksum><cr><lf>
Angle brackets are used as placeholders for data (e.g. <wind speed>) or for non-printable ASCII characters (e.g.
<cr> for carriage return).
Figure 22 lists the various special characters and symbols which are used in the examples given in this Handbook.
Symbol
Valid Characters
HEX Values
Definition
a
{A to Z} {0 to 9} {/}
41-5A, 30-39, 2F
Talker/listener address field characters
c
{A to Z} {0 to 9}
41-5A, 30-39
Fixed length field of alpha (upper case only) and
numeric characters
h
{A to F} {0 to 9} {/}
30-39, 41-46, 2F
Checksum field validation characters
s
{ }
20
Space
x
0 to 9
30-39
Fixed length field of numeric characters
x.x
{0 to 9} {.}
30-39, 2E
Fixed point numeric field (i.e. always with leading
and trailing zeros)
{+ -}
2B, 2D
Polarity indicator. Where a value can take on both
positive and negative values a polarity indicator
( or -) is always sent as the first character
in the field. The field length therefore remains
fixed for both positive and negative values.
{$}
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 22: Symbols used in this Handbook
End of message
delimiter
