Hydrological Services Pty Ltd
Data Logger Model ML1-420
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Copyright
ML1-420 100-4
Issue 1.00 6 Apr, 2011
2. Product Overview
2.1 Overview
The Hydrological Services MiniLog Data Logger is easily installed within many products due
to its small size. Its primary purpose is to count contact closures and measure and log data
from a 4-20mA sensor / transducer.
One such application would be inside a Tipping Bucket Rain Gauge, (TBRG). Rain falling
on the collecting funnel is directed through a syphon control unit and discharges as a steady
stream into a 2 compartment bucket mounted in unstable equilibrium. As each compartment
fills, the bucket tilts alternately about its axis. Each tip forces a contact closure of a magnetic
reed switch corresponding to a height of rainfall depending on bucket capacity, (Bucket
Capacity can be 0.2 mm, 0.5 mm, 1.0 mm, 0.01 inch). The logger unit accepts the contact
closure and records the event as a time stamp to one second resolution. Each event is stored
in secure, non-volatile flash memory.
At the same time the logger can measure water level using a 4-20mA pressure transducer.
The logger switches the external 12V battery voltage to the 4-20mA loop, and waits the
required warmup period, takes a measurement of the 4-20mA current, turns off the loop
power, scales the result and saves each measurement in secure, non-volatile flash memory in
preparation for data extraction.
The data extraction process is accomplished via a PC or similar. A simple one-to-one DB9
cable connection is made between the PC and logger to allow data retrieval upon operator
command. The data format of the logger file is specified within this document.
