Sample Lifetime Calculations; Based On Memory - Valeport MIDAS WLR Hardware Manual

2.4

SAMPLE LIFETIME CALCULATIONS

2.4.1

BASED ON MEMORY

Lifetime based on memory is simple to calculate. Pressure values use 4 bytes of
memory per sample, and temperature uses 2 bytes. Therefore total memory used per
record is 4 + 2 = 6 bytes.
The 16 Mbyte memory actually contains 16,777,216 bytes. Allowing a small amount of
memory usage for header files, the memory will store over 2.7 million records.
The length of time that this memory will last for obviously depends on sampling
scenario. Here are two examples:
Continuous data sampling, 8Hz:
Memory used per second is 8 x 6 bytes = 48 bytes.
Total memory fitted is 16,777,216 bytes.
Seconds before memory full is 16,777,216 / 48 = (approx) 349,500 seconds.
This is equivalent to 97 hours.
This period could be doubled by sampling at 4Hz.
Burst sampling, 4Hz, sampling 1 minute in every 10, recording all data points:
Memory used per burst is 6 bytes x 4Hz x 60 seconds = 1440 bytes.
The memory will therefore be full after 16,777,216 / 1440 bursts = 11650 bursts.
At a 10 minute cycle time, this is 116500 minutes, which is equivalent to 80 days.
Burst sampling, 4Hz, sampling 1 minute in every 10, recording averaged data:
Memory used per burst is 6 bytes.
The memory will therefore be full after 16,777,216 / 6 bursts = 11650 bursts.
At a 10 minute cycle time, this is 2796202 minutes, which is equivalent to 1941 days.
M WLR Hardware Manual
IDAS
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