LSI LASTEM M-Log – User’s manual
37
Calm =
100
*
1
n
Calm
n
Where:
Dir
= instantaneous value of wind direction (0 - 360 °)
Vel
= instantaneous value of wind velocity (m/s)
gra
= conversion of an angle from radians to degrees
rad
= conversion of an angle from degrees to radians
Calm
= 0 in case of not calm wind velocity (< 0.3 m/s), otherwise 1
n
= number of considered valid original data (no error)
5.4
Storing elaborated data
M-Log stores the calculated statistical processings (elaborated data) in the 2-MB internal memory; a
part of this memory (128 kB) is used for configuration information and other internal information;
the real capacity is therefore slightly less than the total storage capacity.
Data storage takes place circularly; once the memory is full, the new data will replace old ones.
By sending a new configuration to the instrument, all data so far stored will be cancelled; this
happens because the new configuration information might be potentially not in tune with them, and
the PC might misinterpret them.
The instrument stores the data in the internal memory only when a
data page
is full; the dimension
of this page equals to 256 bytes; therefore the instrument might store the data only after several
sequences of elaboration; this depends on the programmed elaboration rate, on the number of active
measures and, for each one of them, on the selected elaboration elements. Please note that by
switching off the instrument, some elaborated data inside the
data
page and those not definitely
stored might be lost; for this reason we advise transferring the elaborations which have not yet been
transmitted to the PC before switching off M-Log.
5.4.1
Memory autonomy
Depending on the chosen configuration (measures, types of elaboration for each measure and
acquisition rate) the instrument will work somewhat autonomously as far as the maximum storage
time is concerned, without replacing old data with new ones. The calculation of the time dimension
of the maximum number of storable data is as follows:
A = K / (86400 / RE * NE)
where:
A = number of days of autonomy of the data memory;
K = value subordinate on the size of the used memory; for the 2 MB internal memory, K=386048;
RE = elaboration rate expressed in seconds;
NE = total number of elaboration’s elements programmed for all measures.
