Chapter 4 _________________________________________________________________ Operation 
 
VAISALA ________________________________________________________________________ 79 
MESSAGE 5, Vaisala System Standard 
Message 5 is defined according to Vaisala system standard format. All 
units in the message are SI-units. The message format is as follows: 
FSA
VIS(02000(AL(0)))BL(00100(AL(0)))
CSUM
 
First character of the unit identifier, if the ID is 
not defined it is replaced by a space character 
Visibility identifier and MOR value (unit 
meter, 1 min average) and alarm status related 
to visibility value 
Background luminance identifier and BL value 
(unit cd/m
2 
) and alarm status related to BL 
 
For a list of alarm status code explanations, refer to Table 11 on page 74. 
FD12 Emulation 
For compatibility in the system level, the FS11 sensor also supports the 
message format, frames, and polling format of Vaisala FD12 Visibility 
meter and Vaisala FD12P Weather Sensor. The FD12/FD12P polling 
format is accepted only when the FD12/FD12P message emulation is 
selected. The FD12/FD12P polling format is as follows: 
FD id message_number
 
The parameter message_number refers to the FD message number.