Hach 900 MAX - Manual (Page 122)

Page 120
Programming Features
8990apdx_pfeatures.fm
Appendix B
Power Save Mode.
Selecting a five minute logging interval in Extended Power Mode causes a
reading to be taken and logged every five minutes. All channels must share
the same logging interval.
Note: The Review All Items
selection from the Setup menu
indicates the maximum available
logging hours for the channels and
recording intervals you selected.
The sampler calculates this
information when the program is run
using the
RUN/STOP key.
Longer logging intervals result in a longer total recording time. Lower
resolution also occurs since more averaging is done at higher logging
intervals. Choose the shortest logging interval possible, while still making data
collection convenient. If possible, visit the site once per month to collect data,
and choose a logging interval that almost fills memory over the course of
one month.
For example, if the sampler is equipped with the standard complement of
RAM memory (128K) and only one channel is logged, a two-minute logging
interval would take 24 days to completely fill the available memory
If, on the other hand, a one-minute logging interval is selected, the memory
would become full after 12 days.
Dynamic Memory Allocation
The sampler uses a management scheme called “Dynamic Memory
Allocation.” All readings are logged in battery-backed Random Access
Memory (RAM). RAM memory is allocated to each channel dynamically
during operation. If one channel is logging at five-minute intervals and a
second channel logging at one-minute intervals, the sampler automatically
configures memory so that both channels fill memory at the same time. Five
times as much memory is assigned to the channel that is logging at one-
minute intervals than the channel that is logging at five-minute intervals.
Memory can be configured in two ways:
Table 25 Logging Intervals vs. Total Recording Time for Each Memory Configuration*
Logging Interval
Total Recording Time (days) before
memory is full, with 128K Bytes of
RAM (standard)
(approx. 18,482 readings)
Total Recording Time (days) before
memory is full with 512K Bytes of
RAM (optional)
(approx. 115,630 readings)
1 12.15 80.55
2 24.30 161.10
3 36.45 241.65
5 60.75 402.75
6 72.90 483.30
10 121.50 805.50
12 145.80 966.60
15 182.25 1208.25
20 243.00 1611.00
30 364.50 2416.50
60 729.00 4833.00
* Assuming one logged channel.
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