Sentek RT6, Hardware Manual

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SENTEK
Page 20
6.9 days). The sampling interval can be readily
altered using the software. Note sampling intervals of
less than 10 minutes require external power to be
supplied to the logger as the solar panel may not
provide sufficient charge for long term logging at 1
minute sampling intervals.
The logger memory will only hold a certain amount
of data before the memory “wraps” and the oldest
data is overwritten with newer data. Refer to
Appendix J – Formula to Calculate Logger Storage
Capacity to determine the time before readings are
overwritten in the logger memory.
Between sampling intervals only the removable
logger and part of the Main Board is powered and no
power is supplied to the probes/sensors. When the
sampling interval begins power is supplied to the first
cable run (Run-A) and a signal is sent from the logger
to power up (address) the first sensor. The logger
waits for 0.5 seconds (while sensor stabilizes) then
counts pulses for 0.5 seconds and records the reading
with a time/date stamp. The logger then sends a signal
to power up the second sensor (turning the previous
sensor off) and repeats the process. Once all sensors
configured on Run-A are recorded the logger powers
up Run-B (while removing power from Run-A) and
repeats the process until all sensors configured on
Run-B are recorded. The logger then removes power
from Run-B and waits for next sampling interval.
Therefore the power is only applied to probes/sensors
for a maximum of 32 seconds (32 sensors) at typical
sampling intervals of 15 to 120 minutes which
minimizes power consumption.
The removable logger is fitted with a Ni-Cad battery
which is charged by the solar panel (or external
power supply) and the internal SLA battery. The Ni-
Cad battery protects the contents of the data memory
and time/date clock when the logger is removed to
download data in the office. Once removed from the
logging facility the data is secure for approximately 2
days.