Specifications

HYDROLOGICAL SERVICES
DL3 100-05 IMP
Issue 2: 15/11/2005
Logger
T
ipping Bucket Rain Gauge
Logger
Ext. Power
Rainfall
River Height
RS232 Comm. Port.
Direct or Modem
User Commands
Command Responses
Alarm Messages
Historical Data
Periodic Transmission
2.Product Overview
2.1Overview
The Hydrological Services Rain and River Data Logger unit (shown right as a black box) is easily
installed within a standard Tipping Bucket Rain Gauge, (TBRG). Rain falling on the collecting
funnel is directed through a siphon control unit and discharges as a steady stream into a two
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 0.01 inch of rainfall, (Bucket Capacity = 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
in preparation for data extraction. The logger unit can either be removed
from the TBRG for data retrieval while a fresh replacement logger is fitted
to continue the rainfall record, or a communication medium such as
telephone modem, cellular phone modem, radio modem or satellite modem
may be connected to the logger for periodic data extraction as well as alarm
monitoring.
The data extraction process is accomplishedvia anIBM/AT personalcomputer or similar. A simple
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.
The RRDL-3 can also be connected directly
to a quadrature river height sensor or a 4-
20mA pressure transducer (through an
optional analog interface). The logger is
event triggered when interfaced to the
quadrature sensor, and time period triggered
with the analog pressure transducer. Each
event is stored in secure, non-volatile flash
memory in preparation for data extraction.
When the logger is event triggered and not
connected to an external communication
service, it spends most of its life in a powered
downstate and therefore consumesvery little
power-andmayrunforuptooneyearonits
internal batteries.