Xylem H-340SDI User Manual

Model

H-340SDI

“Smart” SDI-12 Tipping Bucket

Rain Gauge

Owner's Manual

Version 1.1

Design Analysis Associates
75 West 100 South
Logan, UT 84321 USA
Phone: [phone]
Fax: [phone]
Internet: www.waterlog.com
E-mail: [e-mail]

User Agreement/

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1. NATURE OF THE PRODUCT

This agreement accompanies a pressure measuring system comprising micro-coded circuitry and
other electronic equipment sealed in an enclosed housing, and packaged together with written
instructional materials. The packaged electronic circuitry and instructional materials herein are
collectively referred to as the “PRODUCT.” The PRODUCT is made available from DESIGN
ANALYSIS ASSOCIATES, INC., of 75 West 100 South, Logan, Utah 84321 (hereinafter
referred to as “DESIGN ANALYSIS”), and contains information and embodies technology that
is confidential and proprietary to DESIGN ANALYSIS, and the availability and use of the
PRODUCT is extended to you, the USER, solely on the basis of the terms of agreement which
follow.

2. ACKNOWLEDGMENTS BY USER

Opening the package which encloses the accompanying PRODUCT indicates your acceptance of
the terms and conditions of this agreement and constitutes an acknowledgment by you of the
confidential and proprietary nature of the rights of DESIGN ANALYSIS in the PRODUCT.

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3. DUTIES OF YOU, THE USER

In consideration for the access to and use of the PRODUCT extended to you by DESIGN
ANALYSIS and to protect the confidential and proprietary information of DESIGN ANALYSIS,
USER agrees as follows:

(a) USER agrees that they will not open the sealed housing of the PRODUCT, and that

they will take all necessary precautions to prevent their employees, agents, sub­contractors and resellers from doing so.

(b) USER agrees that they will not remove from the exterior of the housing of the

PRODUCT any warnings against opening or notices of proprietary interest placed
thereon by DESIGN ANALYSIS, and that they will take all necessary precautions to
prevent their employees, agents, sub-contractors, and resellers from removing such
markings therefrom.

(c) USER agrees to treat the PRODUCT with the same degree of care as USER

exercises in relation to their own confidential and proprietary information.

(d) USER agrees to return the PRODUCT to DESIGN ANALYSIS if and when the

PRODUCT is deemed to be no longer of use. In return therefore, USER will receive
from DESIGN ANALYSIS a redemption fee of $10.00.

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4. TERM

USER may enjoy these rights only as long as their possession of the PRODUCT shall continue to
be rightful. These rights will cease if the PRODUCT is returned to DESIGN ANALYSIS under
the terms of any redemption offer, warranty, or money-back guarantee, or if USER transfers the
PRODUCT to another party on terms inconsistent with this agreement.

5. LIMITED WARRANTY

(a) What is Covered

DESIGN ANALYSIS warrants that for a period of twelve months from the time of
purchase the functions to be performed by the PRODUCT will be substantially in
compliance with USER documentation. DESIGN ANALYSIS also warrants that the
PRODUCT will be free from defects in materials and workmanship for a period of
ONE YEAR from the date of purchase.

(b) What USER Must Do

If the product fails to satisfy the above warranty, USER must notify DESIGN
ANALYSIS in writing within the applicable period specified above and reasonably
cooperate with the directions they received from DESIGN ANALYSIS.

(c) What DESIGN ANALYSIS Will Do

DESIGN ANALYSIS will repair the PRODUCT or will endeavor to provide a
replacement of same within a reasonable period of time. In the event that DESIGN
ANALYSIS is unable to make the necessary repairs or replacement within a
reasonable period of time, the original purchase price will be refunded upon the
return of the PRODUCT to DESIGN ANALYSIS.

(d) Limitations

(i) THIS LIMITED WARRANTY IS VOIDED WHERE THE SEALED

HOUSING OF THE PRODUCT HAS BEEN OPENED.

(ii) THE ENTIRE REMEDY FOR BREACH OF THIS LIMITED WARRANTY

SHALL BE LIMITED TO REPLACEMENT OF THE DEFECTIVE
PRODUCT OR REFUNDING OF THE PURCHASE PRICE, AS SET
FORTH ABOVE. IN NO EVENT WILL THE LIABILITY OF DESIGN
ANALYSIS TO USER OR TO ANY OTHER PARTY EXCEED THE
ORIGINAL PURCHASE PRICE OF THE PRODUCT, REGARDLESS OF
THE FORM OF THE CLAIM.

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H-340SDI

(iii) EXCEPT FOR THE EXPRESS WARRANTIES ABOVE, DESIGN

ANALYSIS SPECIFICALLY DISCLAIMS ALL OTHER WARRANTIES,
INCLUDING, WITHOUT LIMITATION, ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

(iv) UNDER NO CIRCUMSTANCES WILL DESIGN ANALYSIS BE LIABLE

FOR SPECIAL, INCIDENTAL, CONSEQUENTIAL, INDIRECT, OR ANY
OTHER DAMAGES OR CLAIMS ARISING FROM THE USE OF THIS
PRODUCT, THIS INCLUDES LOSS OF PROFITS OR ANY OTHER
COMMERCIAL DAMAGES, EVEN IF ADVISED OF THE POSSIBILITY
OF SUCH DAMAGES. IN NO EVENT WILL DESIGN ANALYSIS BE
LIABLE FOR ANY CLAIMS, LIABILITY, OR DAMAGES ARISING
FROM MODIFICATION MADE THEREIN, OTHER THAN BY DESIGN
ANALYSIS.

(v) Should the exclusive remedy stated in subparagraph 6 (d) (ii) above be

determined by a proper court of law to have failed of its essential purpose, the
limitation of the obligations of DESIGN ANALYSIS stated in subparagraphs 6
(d) (iii) and (iv) shall remain valid.

(vi) THIS LIMITED WARRANTY GIVES USER SPECIFIC LEGAL RIGHTS.

USER MAY ALSO HAVE OTHER RIGHTS WHICH VARY FROM STATE
TO STATE. SOME STATES DO NOT ALLOW LIMITATIONS ON HOW
LONG AN IMPLIED WARRANTY LASTS OR THE EXCLUSION OF
INCIDENTAL OR CONSEQUENTIAL DAMAGES, SO THOSE
LIMITATIONS OR EXCLUSIONS MAY NOT APPLY.

6. BINDING AGREEMENT

This is a binding agreement, and if not understood, USER should seek competent legal advice.
By paying for the PRODUCT and opening the package, USER acknowledges to have read this
Agreement and have agreed to be bound by its terms and conditions.

7. GOVERNING LAW

This Agreement and its validity and interpretation shall be governed by the laws of the State of
Utah, notwithstanding any choice of law rules of Utah or any other state or jurisdiction.

8. U.S. GOVERNMENT RESTRICTED RIGHTS

Use, duplication, or disclosure by the United States Government is subject to restrictions set forth
in paragraph (c) (1) (ii) of the rights in Technical Data and Computer Software clause at 52.227-

7013. The Contractor-manufacturer is DESIGN ANALYSIS ASSOCIATES, INC., 75 West
100 South, Logan, Utah 84321.

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1.1 Introduction

Chapter 1

H-340SDI Operation

The

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The SDI-12 feature converts a standard tipping bucket rain gauge into a “smart” SDI-12 sensor
with additional capabilities. The H-340SDI is easy to use and works with any data
recorder/logger with a SDI-12 interface. The “Serial-Digital Interface” is ideal for data logging
applications with the following requirements:

 Battery powered operation with minimal current drain
 Low system cost
 Up to 200 feet of cable between a sensor and the data recorder

The H-340SDI has the following features:

 Connects directly to any data recorder with a SDI-12 port.
 Scales the bucket tips into units of inches, meters etc
 Provides built-in accumulation of daily and total rainfall
 Provides mathematical correction for bucket volume errors due to varying rainfall rate.

1.2 Theory of Operation

The H-340SDI has a built-in microprocessor which monitors the tipping bucket sensor.
Whenever a bucket tip occurs the microprocessor wakes up from its low power sleep mode and
adds an appropriate rainfall increment to the rainfall accumulators. The electronics has a filter
circuit which prevents contact bounce in the bucket tip reed switch from causing false counts. In
addition, the time between bucket tips is measured, bucket tips which occur less than 500mS
apart are ignored. This helps protect from false counts of a poorly adjusted bucket mechanism.

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H-340SDI is a Tipping Bucket Rain Gauge with built-in SDI-12 electronics.

The H-340SDI protects its rainfall accumulations with a software flag or “signature.” If the
power is interrupted momentarily the H-340SDI will resume operation using the accumulation
values in memory. If the power is lost long enough to destroy the signature, when the power is
restored the H-340SDI resets the rainfall accumulators to 0000. To intentionally reset the
H-340SDI's accumulators, disconnect the power for 5 to 10 seconds or use the extended “aXRA”
command.

The H-340SDI provides daily rainfall accumulation values which are useful for data loggers
which do not have special provisions for computing daily rainfall. The H-340SDI has a built-in
real-time-clock which triggers a “daily reset time” event. When this event occurs the H-340SDI
automatically updates its “yesterday’s total accumulation” value using “today’s total
accumulation”, then zeros the “today’s total accumulation” value.

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H-340SDI Operation 1-1

During normal operation, the data recorder sends an address together with a command to the
H-340SDI sensor. The H-340SDI wakes up from its low power sleep mode and stores the
requested data in its data buffer. Once the data is ready, the data recorder collects the data from
the H-340SDI's data buffer.

1.3 “Smart Bucket” Theory

Tipping bucket rain gauges have a reputation for being inaccurate. Inaccuracies can be caused by
algae in the bucket, evaporation and poor calibration. The greatest source of inaccuracy however,
is the volume at which the tipping bucket mechanism tips is sensitive to rainfall rate. This occurs
because the water droplets cause surface waves in the bucket and high rainfall rates cause
superposition or “pile up” of extra water in the bucket before it actually tips over. The following
graph shows the relationship between bucket volume and rainfall rate of a typical tipping bucket.
In this example the bucket volume/tip changes from .009 in/tip to .013 in/tip (a 70% change) as
the rainfall changes from 0 to 25 in/hour. To overcome this problem the microprocessor in the
H-340SDI uses an electronic timer to precisely measure the time between bucket tips. This time
value corresponds to the current rainfall rate. On a bucket-by-bucket basis the microprocessor
uses a built-in polynomial to correct for the intensity sensitivity of the bucket mechanism. For
example, bucket tips which are 50 seconds apart (1 in/hr) are computed with a 0.09in/tip
accumulation. Bucket tips 2 seconds apart (25 in/hr) produce a .012in/tip accumulation.

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Figure 1 Bucket tip mechanism sensitivity

H-340SDI

1.4 Making Connections to the H-340SDI

The H-340 has a 6-pin “WAGO” wiring terminal block for connecting the data logger and power.
The terminal block has spring clamp terminals which work with both large and small wires and
provide reliable long-term connections. To open the spring clamp to insert or remove a wire,
insert a small flat screwdriver blade in the square opening adjacent to the wire and twist or pry
carefully to one side.

To Bucket Switch

Internal Cable

SDI Connections

Words of Caution

 Keep the lead wires as short as possible.
 Use shielded cables in noisy environments.

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1.5 Installation

Install the H-340SDI in an open location where it will not be in the rain shadow of trees or
buildings. A rooftop location helps prevent vandalism and the accumulation of leaves and
debris. Bolt or screw the 3-mounting feet to the structure to prevent upset in high winds. Adjust
the three self-leveling screws until the “bulls eye” level is centered.

1.6 Programming Your Data Recorder

You must prepare your data recorder to receive and record the H-340SDI data. Since data
recorders differ widely, refer to your recorder manufacturer's directions. In general, program the
data recorder to input five values via the SDI-12 port. Usually only one or two of the parameters
is actually recorded. Your data recorder must issue an “aM!” command then collect the data with
a “aD0" command, as explained in Chapter 2. The H-340SDI places five data values in its data
buffer:

+AA.AAA+BBB+CC.CCC+DD.DDD+EE.EEE

Where:
+AA.AAA = Rainfall accumulation since last measurement (inches of rain)
+BB = Number of raw bucket tips since last measurement (counts)
+CC.CCC = Total rainfall accumulation since reset. (inches of rain)
+DD.DDD = Total rainfall accumulation today (inches of rain)
+EE.EEE = Total rainfall accumulation yesterday (inches of rain)

All five of these parameters are automatically reset at power-up, or manually with the extended
SDI-12 “aXRA” Reset Accumulators command.

1.7 Programming the H-340SDI

The H-340SDI comes from the factory with the following settings:

SDI Address: 0
Slope: 1.0
Daily Reset Time: 00:00:00
Time of day: 00:00:00

With these values the data will be in units of inches of rainfall. The setup is stored in EEPROM
within the H-340SDI and will not be lost if the power is disconnected. The extended commands
for changing the slope and sensor address are described in detail in Chapter 2. If more than one
sensor is to be connected to the SDI-12 bus, make certain each sensor has a unique sensor
address.

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