Solinst SDI-12 Water Level Temperature Sensor User Guide

SDI-12 User Guide
Water Level Temperature Sensor
October 26, 2023

Introduction

SDI-12 (Serial Data Interface at 1200 Baud) is a communications protocol designed to allow the interfacing of a number of low power analog sensors with a common SDI-12 recorder or datalogger.
This User Guide focuses on the Solinst Model 301 Water Level Temperature Sensor (WLTS) for use as a device in a SDI-12 set up. Configuration, communication, installation and description of the SDI-12 protocol are included.
1.1 WLTS SDI-12 Interface Overview
To connect the WLTS to the SDI-12 customer equipment, you must ensure correct wire-to-wire connection of the cables, including a continuous external power supply to the WLTS (12V). The sensor connects to a Communication Cable (vented or non).
The communication settings for the WLTS comply with the SDI-12 standard at 1200 baud, 1 start bit, 7 data bits, 1 parity bit (even parity), and 1 stop bit. A simple PC Software Utility is used to specify the device address.
The SDI-12 interface circuitry requires the +12V connection to be powered by customer equipment. The current draw from the 12 volt source normally peaks at several 10’s of mA, but idles around 2 mA.

Table 1-1 SDI-12 Interface Cable Wire Definitions

1.2 WLTS SDI-12 System Components
The Solinst Model 301 Water Level Temperature Sensor requires the following components to complete a SDI-12 monitoring system:

• Sensor
• Communication/Vented Cable
• USB-A Programming Cable
• WLTS Software Utility (free download on solinst.com)
• (User supplied equipment

1.3 Sensor Overview & Measurement Parameters
The Solinst Water Level Temperature Sensor is a compact, all-in-one submersible hydrostatic level transmitter that provides continuous, accurate water level and temperature readings for a wide variety of applications.
The durable water level pressure sensor provides 0.05% FS accuracy with automatically temperature compensated readings. There are six pressure ranges to choose from (5-200 m), with options for absolute and vented (gauge) pressure sensor setups.

Water Level Temperature Sensor Specifications

Level Sensor:
Ranges (metres):
Accuracy:
Resolution:
Normalization:
Temp. Comp. Range:| Piezoresistive Silicon with Hastelloy® sensor (Absolute or Gauge)
Absolute: M5, M10, M20, M30, M100, M200 Gauge: M5, M10, M20
± 0.05% FS
0.0006% FS
Automatic Temperature Compensation
0°C to 50°C
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Temperature Sensor:
Operating Temperature:
Temp. Sensor Accuracy:
Temp. Sensor Resolution:
Response Time:| Platinum Resistance Temperature Detector
(RTD)
-20°C to 80°C
± 0.05ºC
0.003°C
1~2 minutes
Communication:
Interface Connector:
Power Consumption:| Digital communications – Modbus and SDI-12
4-Conductor
Max 2mA in idle, 10mA while reading sensor
Size:
Weight:
Wetted Materials:| 22 mm x 192 mm (7/8″ x 7.55″)
173 grams (6.1 ounces)
Delrin ® , Viton ® ,  316L stainless steel, Hastelloy, Polyurethane (TPU boot)

Table 1-1 WLTS Technical Specifications

Note: The Model number (e.g. M5) refers to the maximum depth of submergence in meters below water, for that device.
1.3.1 Absolute Level
When submerged, absolute pressure sensors measure total pressure – the pressure of air plus water column above their zero point. The actual pressure of just water above the sensor is obtained by subtracting barometric pressure from the total pressure.
1.3.2 Vented (Gauge) Level
When submerged, vented pressure sensors detect both water and barometric pressure. However, a vent tube to surface allows barometric effects on the pressure sensor to be eliminated. Therefore, they provide readings of the actual pressure of just water above the pressure sensor zero point.

1.3.3 Temperature
The WLTS records temperature compensated water levels. A Platinum Resistance Temperature Detector is used to accurately compensate for temperature changes within the range of 0ºC to +50ºC.
1.4 Communication/Vented Cable
Communication Cables contain power and communication wires, as well as a vent tube running the length of the cable for the vented sensors. The vent tube and wires are jacketed in polyurethane, providing durability and protection. The cable is 8 mm (0.320″) in diameter, while the connectors are 20 mm (0.790″) in diameter.
Note: The Vented Communication Cables have a vent tube to surface with a Gore vent cap to ensure airflow through, while preventing moisture from entering the tube.

Communication Cable Specifications

Connector: 20 mm (0.79″)
Lengths:| Up to 300 m
Max. Bend Radius:| 25 mm (1″)
Operating Temperature:| -20ºC to 80ºC
Vent Tube Moisture Protection:| Built-in hydrophobic filters at sensor connection
and plug at surface

Table 1-2 Communication Cable Specifications

1.4.1 Communication Cable Connections
To connect the Communication/Vented Cable to the sensor (after programming – see Section 2), line up the pin and socket. Gently push the connections together and twist slightly until you feel/hear a small click when the properly aligned connection is made. Only hand-tighten the coupling while holding the cable still. Tighten the coupling until it seats.

WLTS Software Utility

The WLTS PC Software Utility is a simple tool for configuring the SDI-12 protocol settings and measurement parameters for the Water Level Temperature Sensor. Download the newest version of the WLTS Software
Utility by visiting: https://downloads.solinst.com
Note: The Firmware Upgrade Utility is downloaded along with the WLTS PC Software Utility. See Section 6.2.
The following are the minimal hardware and software requirements for installation and operation:

2.1 Communicating with the WLTS Utility
The WLTS Utility is Windows®-based, and is therefore used with a desktop or laptop PC.
To communicate with the PC, the WLTS must be connected using the supplied USB-A Programming Cable.
To connect to the Sensor, line up the pin and socket. Gently push the connections together and twist slightly until you feel/hear a small click when the properly aligned connection is made. Only tighten the coupling while holding the cable still. Tighten the coupling until it seats. Plug the USB-A Programming Cable into your computer.

2.2 Programming the Water Level Temperature Sensor

With the Sensor connected to the PC with the USB-A Programming Cable and the WLTS Utility started, select the appropriate Com Port for the connected WLTS from the drop-down menu.
Click the ‘Retrieve Settings’ icon . This will retrieve and display the current programmed settings for the connected WLTS, as well as the serial number, firmware version, and model.
Note : The Model number (e.g. M5) refers to the maximum depth of submergence in meters below water, for that device. The ‘A’ indicates an absolute sensor, while a ‘V’ indicates a vented sensor.
You can now customize the WLTS protocol and measurement parameter settings. Select SDI-12 from the Interface drop-down.
SDI-12 settings include the Address (The address can be customized to any value from “0” to “9”, “A” to “Z”, or “a” to “z”, giving a total of 62 unique addresses).
Note : Without setting a specific address, the WLTS will power up with a default SDI-12 device address of 0. The communication settings for the WLTS comply with the SDI-12 standard at 1200 baud, 1 start bit, 7 data bits, 1 parity bit (even parity), and 1 stop bit.
Set the units that the WLTS will be measuring in for the Level and Temperature Channels. For vented sensors, you can also perform a “Vented Sensor Zero” in air. Click Zero, you will receive a confirmation that the sensor has been zeroed. Click OK.
The parameters that were changed will be indicated by a blue highlight. When finished, click Upload Settings To Sensor. You will receive a confirmation message that the settings were uploaded. Click OK.

To test that the Sensor is reading correctly before connecting it to the Communication/Vented Cable for
deployment, you can click the ‘Real Time Reading Verification’ icon to obtain real-time readings from the Sensor.
If further Diagnostic Information is required, click the ‘WLTS Diagnostics Information’ icon to perform a series of tests (Memory and Sensor) and obtain Level and Temperature information that may be helpful when troubleshooting any issues. Take a screenshot of this information to share for troubleshooting support.

SDI-12 Wiring Setup and Installation

3.1 SDI-12 Wiring Setup

1. Be sure that an WLTS is properly connected to the Communication/Vented Cable (see Section 1.4.1).
2. Turn off the power to the SDI-12 recorder and/or the SDI-12 network.
3. Refer to the wiring diagram below for correct connection of the Communication/Vented Cable to the SDI-12 recorder, including external power (12V).
4. Turn on power to the SDI-12 recorder and/or the SDI-12 network such that power is applied to the Protocol Connector Cable.

3.2 Installation

It is recommended that the WLTS be installed in a vertical orientation. However, inclined or horizontal installation is acceptable. The pressure sensor measurement line (zero point) is indicated by the machined line around the sensor body.
The pressure transducer is oriented in a plane normal to the long axis of the body, and detects pressure directed along the plane of the long axis. In vertical orientations, the sensor detects pressure above the pressure transducer line. In non-vertical orientations, the pressure zero point is proportional to the angle of inclination.
Before Deployment, make sure you do the following:

• Program your WLTS, using the WLTS Utility, with the correct settings

• Determine deployment depth to ensure the WLTS does not touch the bottom of a tank, well, etc. (avoid submergence in sediment).
  Note : The WLTS can withstand over-pressurization of 2 times the intended range, e.g. a Model M10 can accommodate a fluctuation of 20 meters or 60 feet and still record pressure. However, over-range accuracy is not guaranteed.

• Determine the minimum and maximum expected water levels, as the WLTS must remain submerged for the entire monitoring period, without over-ranging the pressure sensor.
  Note : The length of the Communication/Vented Cable should not be assumed as the deployment depth, as there may be some slack in the cable.

• Use a Solinst Model 101 or 102 Water Level Meter to take a manual depth to water measurement that will be used to verify WLTS readings.
  Note : It is recommended to take a manual water level measurement before installing a WLTS, shortly after installation, periodically during your monitoring interval, and at the end of your measurement period. Use these measurements to verify WLTS readings, and for data adjustments later on. Ensure you take manual readings as close in time as possible to a scheduled WLTS reading.

Deployment

• The WLTS is designed to be conveniently installed in a number of applications, as long as proper precautions and recommendations are followed.
• The nose cone of the Sensor can be removed to make use of the 1/4″ NPTM threaded connection.
• Do not drop the WLTS into the water, carefully lower it into place. Avoid installing in areas where “water hammer” or hydraulic jump” (very sudden, large increases in pressure) may occur.
• Be careful not to nick or bend the Vented Cable during installation (use a maximum 1″ (25 mm) bend radius as a precaution).

After Deployment, make sure you do the following:

• Take a manual depth to water measurement after the WLTS has stabilized (approximately 10 minutes).
• Take another manual depth to water measurement just before removing the WLTS.

3.2.1 Installation in a 2″ Well
Solinst offers an optional Support Hanger Bracket and a 2″ Well Cap Assembly, which consists of an insert, well cap base and well cap.
The 2″ Well Cap Assembly insert has two openings which can optionally be used to install the Communication Cable. The second opening can be used to take manual water level measurements while the Water Level Temperature Sensor is recording down-well. When the openings are not in use, two red plugs are supplied with the assembly.
Note: A third 0.7″ ID access hole allows additional monitoring equipment in the well, such as a Water Level Meter for manual field measurements.
Note: To accommodate 4” wells, a separate adaptor is available for use with the 2” well cap base.

The following steps provide some guidance on how to install the Water Level Temperature Sensor using the Support Hanger Bracket and 2″ Well Cap Assembly:

1.  Slide the well cap base onto the well casing. Do not secure it at this point.

2. Place the Support Hanger Bracket in the well cap base so it seats on the shoulder in the base. Place the insert into the well cap base.
   Note : There are three holes in the top of the Support Hanger Bracket that can be used to secure it in the well cap base with screws.

3. Remove one of the red plugs from the insert. Lower the WLTS connected to the Communication Cable through the opening and down the well until the wires at the top of the cable are above the insert. Remove the other red plug from the insert and take a manual depth to water measurement for your records.

4. Lift the well cap base with Support Hanger Bracket and insert from the well casing. Wrap the Communication Cable around the Support Hanger Bracket and slide into the cutouts to secure the cable to the bracket.
   Note: The holes in the bracket can accommodate twist ties or zip ties to secure the cable to the bracket if desired.

5. Lower the well cap assembly back onto the well casing. Secure the well cap base to the well casing if desired. Install the well cap when the WLTS is not in use.

3.2.2 Biofouling Conditions
Biofouling is the unwanted buildup of microorganisms, plants, algae, or organisms such as barnacles and muscles on a wetted surface. When a Water Level Temperature Sensor is deployed for an extended period of time, especially in a saltwater environment, there is the risk of biofouling. Biofouling on the pressure sensor can compromise the accuracy of the measurements.
A Solinst Biofoul Screen can be used to protect the WLTS from biofouling. The copper-coiled Delrin screen naturally reduces biofouling, and lengthens the time a WLTS can be deployed before maintenance is required. The Biofoul Screen simply slips onto the sensor end of the WLTS where it is held in place with its compression fitting. It allows water to freely enter the pressure transducer inlets. It is replaced as required.

WLTS SDI-12 Operation

Once the WLTS system has been installed and powered up, you can start issuing SDI-12 commands to it. It is good practice to do the following:
Note: In all the following SDI-12 commands discussed, ‘a’ = the SDI-12 device address assigned the WLTS.
4.1 The SDI-12 Address
The factory default address for an WLTS is “0”. This address identifies the WLTS on an SDI-12 network. The SDI-12 ‘A’ command is supported, so the SDI-12 device address may be changed through this command, or by using the WLTS PC Software Utility.
Note: For explanations of the SDI-12 Supported Commands used to communicate with the WLTS, see Section 5.

4.2 Activation and Verification

1. Check the SDI-12 device Address of the WLTS on your SDI-12 network. The default is set to address ASCII ‘0’
2. Using your SDI-12 recorder and its software, issue an Acknowledge Active Command ‘a!’, to test if the device address is correct and you can communicate with the newly installed WLTS. Make sure other SDI12 devices are not being addressed and communicating at the same time on the SDI-12 network.
3. Issue the Start Verification Command ‘aV!’ and later read it with the Send Data Command ‘aD0!’ to verify the WLTS is operating without errors.
4. Use the Send Identification Command ‘aI!’ to verify that the name and model of the WLTS matches that of the WLTS you have just installed. This information was read out of the WLTS with the last ‘V’ command, or the last SDI-12 interface bring-up.
5. Execute the Start Concurrent Measurement Command ‘aC!’ and later retrieve the measurement with the Send Data Command ‘aD0!’, to ensure the WLTS is connected properly and taking measurements .
6. If the above steps are successful, you may program the SDI-12 recorder to automatically issue commands to the WLTS to take measurements and record them.

SDI-12 Supported Commands

Please refer to the document: SDI-12: A Serial Digital Interface Standard for Microprocessor-Based Sensors, Version 1.3, July 18, 2005, prepared by the SDI-12 Support Group (Technical Committee), for a complete description of the SDI-12 protocol. (http://www.sdi-12.org/).
Note: In all the following SDI-12 commands discussed, ‘a’ = the SDI-12 device address assigned the WLTS.
The following commands are supported:

5.1 Acknowledge Active Command: a!
This command is used to ensure that an WLTS is responding to the SDI-12 recorder. A typical command/ reply would be: 0!/0 where the ‘0’s represents the WLTS SDI-12 device address and represents a carriage return (Hex 0D) and represents a line feed (Hex 0A). All replies from an WLTS are terminated with . All SDI-12 recorder commands are terminated with an exclamation mark ‘!’ character.

5.2 Address Query Command: ?!
Using a question mark (?) as the address character causes the WLTS to respond with the acknowledge active ‘a!’ command where ‘a’ represents the WLTS address. A typical command/reply would be: ?!/0.
The bold-faced characters are sent to the WLTS; the normal type-face is the WLTS’s reply. In this case the WLTS address is “0”. This command is good for determining the WLTS address, if it is the only sensor connected on the SDI-12 network.
5.3 Send Identification Command: aI!
This command is used to query WLTS for their SDI-12 compatibility level, model number, sensor type, firmware version, and serial number. A typical command/reply would be 0I!/013SOLINST M20V V1 1.000 1234567 where the first “0” is the WLTS address, “13” represents SDI-12 V1.3 protocol support, “SOLINST ” (8 characters) identifies the WLTS manufacturer, “M20V ” (6 characters) defines the WLTS sensor model number (Mxxx) and vent type(V or A), “V1 ” (3 characters) is the hardware identifier, “1.000” specifies the current firmware version, and “1234567” represents the WLTS serial number.
5.4 Change Address Command: aAb!
This command is used to change the WLTS SDI-12 address. A typical command/reply would be 0A1!/1 where the “1” is the new address.
5.5 Start Measurement Command: aM!
This command tells the WLTS to take a measurement. However, the measurement is not returned after this command. Instead, the time and number of measurements that can be expected will be replied. For example:
0M!/00102 where the first “0” is the WLTS address, the next three digits “010” represent the time in seconds it will take the WLTS to take the readings, and the final “2” indicates how many readings will be returned. The Solinst WLTS will return a temperature and level measurement which are always ready to be read after the specified time, after that the SDI-12 recorder can issue the Send Data command 0D0! to retrieve the measurement data. Other start measurement commands such as aM1 to aM9 are reserved for future use.

5.6 Start Measurement Command with Checksum: aMC!
This command is identical to the aM! command with the exception that a three- character checksum is returned before the as part of the Send Data command reply. The aMC1 to aMC9 commands are reserved for future use.
Note: Checksum is a form of redundant test, which is used to check for any errors in the data.

5.7 Send Data Command: aD0!
This command is used to get groups of data from the WLTS. An aD0! command is issued by the recorder after a M, MC, C, CC, or V command. The WLTS responds by sending the data. For a Solinst WLTS, this is currently two data items: temperature and level measurements. A typical command/reply is:
0D0!/0+24.2981+0.35212) where the temperature is the “+24.2981” in degrees Celsius and the level is the “+0.35212” in meters. It is possible to change level units using the WLTS PC Software Utility, but the actual units in use are not reported while the WLTS is in SDI-12 mode.
Note: The actual units in use are not reported to the SDI-12 recorder while the WLTS is in SDI-12 mode, but it is possible to change level units using the WLTS Utility.
In response to a checksum request i.e. MC, CC; a typical command/reply is: 0D0!/0+24.2981+0.352 12MQ where the temperature and level are as before and the final “MQ” is the checksum.
Refer to the SDI-12 specification for details on the checksum generation. For the M and C commands if a measurement cannot be obtained, the D command will return 0000 to indicate the measurement could not be obtained. The aD1 to aD9 commands are reserved for future use.
5.8 Start Concurrent Measurement Command: aC!
This command is similar to the Start Measurement Command except a concurrent measurement is taken.
Like the Start Measurement Command, a Send Data Command is required to retrieve the data. For example:
0C!/000302. The reply indicates that two readings (temperature and pressure) are available after 3 seconds. A 0D0! command is then issued to read these WLTS values. The aC1 to aC9 commands are reserved for future use.
5.9 Start Concurrent Measurement Command with Checksum: aCC!
This command is similar to the Start Concurrent Measurement with the addition of a checksum. For example:
0CC!/00302 would then, after 3 seconds, reply to the aD0! command as follows:
0D0!/+24.6038+0.34513Lj. Where “Lj” is the checksum for the two measurement values “+24.6038 + 0.34513. The aCC1 to aCC9 commands are reserved for future use.

Table 5-1 BIT Verification Fault Codes

Maintenance and Troubleshooting

6.1 Maintenance
As with any monitoring project, you should select the proper equipment and determine a maintenance schedule based on the environment specific to your application.
For the WLTS, this means selecting the appropriate pressure range, ensuring the monitoring temperatures are within the instruments specifications, and making sure the wetted materials are compatible with site chemistry.
Simple maintenance tips include:

• Clean the connections to ensure a proper seal. A cotton swab can be used to clear any moisture, or debris from the connectors.
• Keep the dust caps on all of the connections, when not in use.
• Store the WLTS in its case, and the Communication/Vented Cable on its spool when not in use.
• Clean the WLTS as required.

6.1.1 Sensor Maintenance
To ensure the vent tube remains dry, the gauge WLTS contains a permanent desiccant and hydrophobic membrane at the connection to the Vented Cable—there is no need to replace them.
Sensor maintenance consists of cleaning the outside housing, the circulation holes in the nose cone and the NPT threading. The required frequency of cleaning is dependent on several aspects of the monitored waterquality. In freshwater with good to excellent water quality, the cleaning requirements will be very minimal; amounting to a seasonal or even annual maintenance inspection.
In most cases cleaning can be accomplished by rinsing the sensor and using mild, non-residual, non-abrasive household cleaners with a very soft-plastic, bristled, pipe-cleaner type brush. Do not insert any object through the sensor end.
In some cases simple cleaners are insufficient to properly clean the sensor. Several commonly occurring water conditions require specific maintenance methods. These include hard water, high suspended solids loading, biological or chemical fouling and salt or brackish water conditions.
Hard water monitoring can result in the precipitation of calcium and magnesium deposits on the pressure transducer as well as other components of the sensor. These deposits can be safely dissolved using a diluted solution (typically ≤ 10% strength) of acetic or phosphoric acid. Commercially available products for dissolving hard water scaling are also available and can be used if designed for household use. Some industrial strength hard water scaling removers are much higher strength and are not recommended for cleaning the sensor.
High suspended solids load may block the circulation ports or clog the internal pressure cell of the sensor.
The potential clogging effect of solids deposition can be minimized by placing the sensor in zones of flow.
To remove solids build up, rinse the sensor under a low flow of tap water until particles have been washed away.
Bacteriological or chemical fouling can be an important consideration in many ground and surface water monitoring projects. Sessile bacteria will often utilize installed instrumentation as an attachment substrate.
Chemical deposit can be the result of electrical charge differential between the instrumentation of the monitored liquid or the result of biological or algal activity. Both forms of fouling can result in difficult to remove deposits on the sensor transducer, the conductivity wires and the sensor casing. To remove fouling use a diluted (≤10%) solution of sulfuric acid. Persistent material may require soaking for several hours.

6.1.1.1 Changing or Updating WLTS
If a new WLTS is attached or you have changed the settings, ensure that the power is disconnected temporarily (30 seconds) by disconnecting the Communication/Vented Cable from the sensor. This is so the SDI-12 translator will re-initialize, in order to cause the new SDI-12 device address or settings to be retrieved from the WLTS.
6.1.2 Communication/Vented Cable Maintenance
Proper storage of the Communication/Vented Cable is very important. The cables are shipped with the end capped; the cap should be retained, and used to seal the connection when not in use and during periods of storage. For Vented Cables, the Gore vent cap on the end of the vent tube at surface should never be removed.
It is also recommended the Vented Cable be stored on the spool it was received on (for longer lengths). This protects the Cable and avoids the vent tube from being kinked.
Note : Before the Vented Cables are shipped, the vent tubes are blown dry with nitrogen gas, and capped, to ensure no moisture during transport.
To ensure the vent tube is dry before deployment or storage, Solinst offers a Vented Cable Blowout Fitting that allows you to blow nitrogen gas through the tube. Contact Solinst for more details.
Cleaning the connection ensures a proper seal. A cotton swab can be used to clear any moisture or debris from the connector.

6.2 Firmware Updates
The Water Level Temperature Sensor been designed with firmware that is easy to update whenever useful new functions or other improvements become available, as with software releases.

To update the firmware in your sensor, go to the Solinst Website at: https://downloads.solinst.com where you can sign-in or register to download the firmware upgrade file that is contained within a Zip Archive. Ensure you unzip the Archive to access the firmware *.ssf file.
Note: It is important that the communication between the PC and the sensor is not interrupted during a firmware upload, so please make sure to close any other running programs, including screen savers, and do not disconnect the sensor before the upload is finished.
To upload new firmware to a Water Level Temperature Sensor, follow these steps:

1. Connect the sensor to your PC using the USB-A Programming Cable.

2. Open the Solinst Firmware Upgrade Utility from the shortcut created on your desktop when the WLTS Utility was downloaded. Select the Com Port that the sensor is connected to from the drop-down menu.

3. Click the ‘Open’ button , which should open a file dialog asking for the firmware file (*.ssf) to upload.
   Navigate to the directory where the firmware file was saved on your PC, then click on the file and click ‘Open’.

4. Check the ‘File Information’ box to make sure the opened file is correct.

5. Click the ‘Upload Firmware’ button , to start the firmware upload process.
   If a communication error occurs and is indicated in the ‘Datalogger Status’ box either before or after the “Verifying Firmware” and “Loading Firmware to Datalogger” messages, then restart the upgrade process.

6. If, however, a communication error occurs between the “Verifying Firmware” and the “Loading Firmware to Datalogger” messages, then please contact Solinst. You will need to give the sensor Serial Number and explain the exact positioning of the error message.

Note: When conducting a firmware upgrade, DO NOT interrupt the process prior to completion (This may take 2 to 4 minutes).
Installation is not complete until a note appears at the base of the program window indicating “Firmware Update Completed”.

6.3 Troubleshooting
WLTS Does Not Reply
The most common error is that SDI-12 commands are being sent with an address which does not match the actual device address of the WLTS being used, in which case the WLTS will not reply. Try changing the address of the SDI-12 command being sent.
The recorder receives badly formatted replies from the SDI-12 network of WLTS.
Check that all WLTS’s on the network have different and unique device addresses. Otherwise there will be data bus collisions and scrambled data will be returned on replies to the recorder or SDI-12 recorder.
Received an invalid response to the D command, e.g. 0000
Retry the command. The WLTS may have been busy, or not connected properly to the Communication/ Vented Cable. If your recorder supports automatic retries consider enabling that function.

References

SDI-12 Support Group (Technical Committee). SDI-12: A Serial-Digital Interface Standard for Microprocessor-Based Sensors, Version 1.3, July 18, 2005. Available [online]: http://www.sdi-12.org/

www.solinst.com
High Quality Groundwater and Surface Water Monitoring Instrumentation
Solinst Canada Ltd., 35 Todd Road, Georgetown, ON L7G 4R8
Tel: +1905-873-2255; 800-661-2023 Fax: +1 905-873-1992
instruments@solinst.com

Documents / Resources

| Solinst SDI-12 Water Level Temperature Sensor [pdf] User Guide
SDI-12 Water Level Temperature Sensor, SDI-12, Water Level Temperature Sensor, Level Temperature Sensor, Temperature Sensor, Sensor
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References

• Solinst Groundwater and Surface Water Monitoring Instrumentation, Water Level Meters, Interface Meters, Dataloggers
• SDI-12 Support Group
• Solinst Groundwater and Surface Water Monitoring Instrumentation, Water Level Meters, Interface Meters, Dataloggers
• Member Modal For CF Members
• Solinst Groundwater and Surface Water Monitoring Instrumentation, Water Level Meters, Interface Meters, Dataloggers
• Solinst Water Level Temperature Sensor Quote Form
• 301 Water Level Temperature Sensor Instructions
• Water Level Temperature Sensor: Submersible Level Transmitter

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