Chapter 5 ________________________________________________________________ Operation
VAISALA ______________________________________________________________________ 177
BL(00100(AL(0))) = Background luminance identifier and BL
value (unit cd m
-2
) and alarm status
related to BL value
#
= End of the text
CSUM =
Checksum
CRC16
$
= End of the transmission
-*
= CR + LF
For a list of alarm status code explanations, refer to Table 13 on page
164.
The total amount of characters in the message is 46. The transmission
times are: 1.5 s at 300 bps (10-bit char), 0.19 s at 2400 bps, 0.05 s at
9600 bps.
Message 5 and 6 - FD12 Emulation
For compatibility in the system level, LT31 also supports the message
format, frames, and polling format of Vaisala Visibility Meter FD12. The
FD12 polling format is accepted only when the FD12 message emulation
is selected.
The FD12 polling format is as follows:
%
FD id message_number
-
The
Message_number
parameter refers to the FD message number.
Message 5 - FD12 Message 2
The emulation mode for FD12 message 2 is selected with the
SET
MESSAGE TYPE FD12MSG2
command.
The message format of the emulated Vaisala FD12 message number 2 is
presented below:
!
FD A
"
00 1810 1353 //// // /////
#-*
----------------------------------------
¦¦ ¦ ¦ ¦ ¦ ¦_____
reserved for options
¦¦ ¦ ¦ ¦ ¦________
reserved for options
¦¦ ¦ ¦ ¦_________
reserved
¦¦ ¦ ¦_________
visibility 10 min average in meters
¦¦ ¦________
visibility 1 min average in meters
¦¦____
hardware status
0 = OK
¦
1 = alarm (data OFF, see STATUS message)
¦
2 = warning (see STATUS message)
¦_______
data status
0 = normal, FD12 alarm limits not supported