Model H-312 and H-312-22 Submersible Pressure Sensor With SDI-12 Output Owner's Manual Version 1.1 D E S I G N A N A L Y S I S A S S O C I A T E S , I N C. 75 West 100 South, Logan, Utah 84321 Phone: (435) 753-2212 Fax: (435) 753-7669 Web: http://www.waterlog.com E-mail: waterlog@waterlog.
D E S I G N A N A L Y S I S A S S O C I A T E S , I N C. 75 West 100 South, Logan, Utah 84321 Phone: (435) 753-2212 Fax: (435) 753-7669 Web: http://www.waterlog.com E-mail: waterlog@waterlog.
User Agreement/ WATERLOG® Warranty 1. NATURE OF THE PRODUCT This agreement accompanies a pressure measuring system comprising firmware, circuitry and other electronic equipment 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.
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.
Chapter 1 Introduction 1.0 Introduction The WATERLOG® H-312 is a submersible pressure transducer specifically designed for water level monitoring. The H-312 is easy to use and works with any SDI-12 data recorder. The “Serial-Digital Interface” is ideal for data logging applications with the following requirements.
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1.2 Check The Sensor Cable Be sure that the vented cable is long enough to reach from the submerged location selected to the junction box of the dry air system. Also, be sure that the data logger cable is long enough to reach from the dry air junction box to your data recorder 1.3 Check The Model Number Before installing your new WATERLOG® H-312, check the information on the label of the sensor enclosure.
1-4 Introduction H-312
Chapter 2 Installation 2.1 Installing the WATERLOG® H-312 The H-312 submersible pressure sensor is very versatile and can be used in many water monitoring applications.
2.2 Water Depth The following chart shows the maximum depth to which the H-312 is factory calibrated. The sensor can survive temporary operation up to twice the maximum rated depth for you model’s range. However, any pressure measurements made beyond the rated depth will be inaccurate. The H-312 will be damaged if it is placed deeper than twice the maximum rated depth. Model Pressure Range Depth Range * Accuracy H-312-15 0 to 15 psi 0 to 34.60 ft. +0.017 ft H-312-30 0 to 30 psi 0 to 69.20 ft. +0.
protect the sensor cable so it remains at the temperature of the surrounding air and is not heated directly by the sun. 2.4 Stilling Wells The H-312 can be hung in well bores, stilling wells and standpipes. The H-312 should be installed by suspending the sensor using a small stainless steel cable, not by its polyurethane electrical cable. A weighted ballast or sinker, such as the one that is provided will pull the cable tight at the desired depth and will help the sensor to hang straight down.
2.5 Dry Air Junction Box Because the surface of the water being measured is exposed to atmospheric pressure, submersible pressure sensors must provide correction for changes in barometric air pressure. Several industry designs employ a sealed sensor housing and measure the atmospheric pressure separately. This scheme however, doubles the offset drift because two pressure sensors are needed. To provide the best accuracy possible, the H-312 uses an atmospheric referenced pressure sensor design.
Figure 7 Dry Air Junction Box Wiring Data Logger Connections Wire Name Red White Black Shield +12Volt DC SDI-12 Data Ground Ground If the polyurethane cable between the H-312 sensor and the dry air junction box must be routed thru a conduit or small hole, the polyurethane cable can be temporarily disconnected from the dry air junction box as needed.
2.7 Wiring and Installation Precautions The shield in the hook-up cable must be connected to the data logger ground. The data recorder must be earth grounded. The H-312 requires that the water be at ground potential. Mother Nature takes care of this for surface and ground water. Make certain the seals in the liquid tight cable fittings on the dry air junction box are tight. Make certain the dry air junction box lid is screwed on and sealed properly.
2.9 Programming the SDI-12 Address If more than one sensor is to be connected to the SDI-12 bus, make certain each sensor has a different sensor address. The H-312 comes from the factory with its address set to “0". The address can be changed with an extended SDI-12 command (see Chapter 4). 2.10 Programming the H-312 Sensor The H-312 comes from the factory with the following settings: SDI Address: Slope: Offset : MeanCount: 0 2.3067 (feet of H20) 0.
2.12 Testing Before installing the H-312 in your field location, you may wish to first test the sensor and data logger in your shop or lab. This allows you to become familiar with H-312 and the data logger in a controlled environment. The H-312 can be tested in a bucket of water. However, for this test to work correctly, you must run a wire from inside the bucket that comes in contact with the water back to the chassis ground of the data recorder.
Chapter 3 Maintenance 3.1 Maintenance Sustained operation of the H-312 pressure sensor is almost maintenance-free. Experience has shown that moisture condensing in the atmospheric reference tube creates the largest percentage of field problems. The desiccant in the H-312 junction box dry air system should be changed on a fixed schedule, normally every three to six months. Different areas in the world have widely varying humidity and temperature fluctuations.
3.4 Cleaning the Port Screen The H-312 has a port screen to help prevent dirt, sediment and insects from entering the sensor pressure port. The screen is a circular stainless steel band with .025 square holes. A 149 micron polypropylene plastic screen is located underneath the stainless screen. Occasionally the port screen and the pressure ports may need to be cleaned, rinsed out or replaced . Replacement stainless steel and polypropylene screens are available if needed.
CAUTION: Do not use sticks and the like to push sediment out of the ports. This may cause a hydraulic effect and over pressure the internal sensor. Use common sense. Step 5 Reinstall the plastic and the stainless steel screens. Position the joints of the stainless and plastic screens 180 apart. One end of the stainless steel screen has a slight bend. Position the bent end on the outside to help keep the sharp end from protruding out.
3-4 Maintenance H-312
Chapter 4 SDI-12 Command and Response Protocol 4.0 SDI-12 Command and Response Protocol This is a brief description of the Serial Digital Interface (SDI-12) Command and Response Protocol used by the WATERLOG® Series Model H-312 sensor. Included is a description of the commands and data format supported by the H-312. Refer to the document "A SERIAL DIGITAL INTERFACE STANDARD FOR HYDROLOGIC AND ENVIRONMENTAL SENSORS.” Version 1.
4.1 Measure Command The Measure Command causes a measurement sequence to be performed. Data values generated in response to this command are stored in the sensor's buffer for subsequent collection using "D" commands. The data will be retained in the sensor until another "M", " C", or "V" command is executed. Command "aM!" Response "atttn" Description Initiate measurement Where: a is the sensor address ("0-9", "A-Z", "a-z", "*", "?").
4.2 Concurrent Measurement Command This is a new command for the Version 1.2 SDI-12 Specification. A concurrent measurement is one which occurs while other SDI-12 sensors on the bus are also taking measurements. This command is similar to the “aM!” command, however, the nn field has an extra digit and the sensor does not issue a service request when it has completed the measurement. Communicating with other sensors will NOT abort a concurrent measurement.
4.3 Send Data Command The Send Data command returns sensor data generated as the result of previous "aM!", "aC!", or "aV!" commands. Values returned will be sent in 33 characters or less. The sensor's data buffer will not be altered by this command. Command "aD0!" through "aD9!" Response "apd.d ... pd.d" Where: a is the sensor address ("0-9", "A-Z", "a-z", "*", "?"). D0..D9 are upper-case ASCII characters. p Is a polarity sign (+ or -) d.
4.4 Continuous Measurements This is a new command for the Version 1.2 SDI-12 Specification. Sensors that are able to continuously monitor the phenomena to be measured, such as a cable position, do not require a start measurement command. They can be read directly with the R commands (R0!...R9!). The R commands work exactly like the D (D0!...D9!) commands. The only difference is that the R commands do not need to be preceded with an M command.
4.6 Initiate Verify Command The Verify Command causes a verify sequence to be performed. The result of this command is similar to the "aM!" command except that the values generated are fixed test data and the results of diagnostic checksum tests. The data generated in response to this command is placed in the sensor's buffer for subsequent collection using "D" commands. The data will be retained in the sensor until another "M", "C", or "V" command is executed.
4.7 Send Identification Command The Send Identification Command responds with sensor vendor, model, and version data. Any measurement data in the sensor's buffer is not disturbed. Command "aI!" Response "allccccccccmmmmmmvvvxx...xx" Where: a is the sensor address ("0-9", "A-Z", "a-z", "*", "?"). I is an upper-case ASCII character. ll is the SDI-12 version compatibility level, e.g. version 1.2 is represented as "12".
4.8 Change Sensor Address Command The Change Sensor Address Command allows the sensor address to be changed. The address is stored in non-volatile EEPROM within the sensor. The H-312 will not respond if the command was invalid, the address was out of range, or the EEPROM programming operation failed. Command "aAn!" Response "n" Description Change sensor address Where: a is the current (old) sensor address ("0-9", "A-Z", "a-z", "*", "?").
4.9 Extended Set_Current_Stage Command The H-312 processes the pressure sensor input and computes Pressure in PSI units. Stage is computed with a Stage = m * Pressure + b equation. During installation it is convenient to quickly set the H-312's Stage reading to match the current stage or elevation of the water as determined by a staff gauge or other datum. This command causes the H-312 to make a fresh measurement and automatically update the Offset (b) term as needed to produce the desired Stage.
4.10 Extended Read/Write Stage_Offset and Read/Write Stage_Slope The H-312 processes the pressure sensor input and computes Pressure in PSI units. Stage is computed with a Stage = m * Pressure + b equation. The Slope (m) and Offset (b) terms are programmable, allowing the user to scale the reading into other engineering units. These commands allow the user to read or write (change) the Stage_Slope and Stage_Offset terms. The slope is set to 2.3067 and the offset to 0.00 at the factory.
4.11 Extended Read Mean_Count and Write Mean_Count The H-312 makes multiple raw sensor measurements, discards the high and low values, integrates (averages) the measurement data and computes Pressure (PSI). The number of raw sensor measurements made for each SDI-12 measurement sequence is programmable. When measuring turbulent water, tides or other special applications Mean_Count can be changed to increase or decrease the number of pressure measurements made during the SDI-12 measurement sequence.
Example of a H-312 Extended "Read Mean_Count" command: Command Response "aXRMC!" Time Values Description "a0011" 1 sec 1 Read Mean_Count Command Response "aD0!" "a+16" Description Count = 16 Example of a H-312 Extended "Write Mean_Count" command: Command Response "aXWMC8!" Time "a0011" 1 sec Values Description 1 Write Mean_Count Command Response "aD0!" "a+8" Description Count = 8 4-12 SDI-12 Command and Response Protocol H-312
4.12 Extended “XTEST” This command is used for installation or production testing and requires the use of a H-419 Sidekick interface and a PC. This command causes the H-312 to transmit unsolicited real-time data for testing purposes. The test mode is used to help troubleshoot the installation by providing a continuous readout of pressure data. This is not compliant with the SDI-12 specification and is not used with data loggers. To activate the test mode, send the command “aXTEST!” from the PC.
4-14 SDI-12 Command and Response Protocol H-312
Appendix A H-312 Specifications Accuracy (Maximum percent of error in measurement) Pressure: Less than or equal to 0.05% of full scale output (FSO) over temperature range referenced to a straight line stretched from zero PSI to maximum pressure Temperature: Internal temperature ±1° C over temperature range Resolution (Smallest change detectable in output signal) Pressure: 1 part in 1,000,000 (0.0001%) Temperature: 1 part in 1,000,000 (0.0001%) Linearity Less than 0.
4-2 SDI-12 Command and Response Protocol H-312
Appendix A H-312-22 Specifications Accuracy (Maximum percent of error in measurement) Pressure: Less than or equal to 0.02% of full scale output (FSO) over temperature range referenced to a straight line stretched from zero PSI to maximum pressure Temperature: Internal temperature ±1° C over temperature range Liquids and gases compatible with PVC, ABS, RTV and stainless steel. Polyurethane cable is not compatible with water having high concentrations of chlorine.
4-2 SDI-12 Command and Response Protocol H-312
