Campbell Scientific AG SDI-12 User Manual

SSDDII--112

Probe Interface Manual Version 3.4

(For firmware revision 1.2.3 or above)

transmitted in any form electronic or mechanical for any purpose whatsoever without the prior written consent

of Sentek Pty Ltd. All intellectual and property rights remain with Sentek Pty Ltd.

All information presented is subject to change without notice.

 2003 Sentek Pty Ltd

EnviroSMART, EasyAG and TriSCAN are registered trademarks of Sentek Pty Ltd.

Details of SDI-12 specifications can be obtained from the SDI-12 Support Group, Technical Committee, at www.sdi-12.org.

Sentek Pty Ltd

A.C.N. 007 916 672 77 Magill Road Stepney, South Australia 5069

Phone: +61 8 8366 1900 Facsimile: +61 8 8362 8400 Internet: www.sentek.com.au Email: sentek@sentek.com.au

EnviroSMART® and EasyAG® - Statements of Compliance

FCC note of compliance and statement of liability

Electro-Magnetic Compliance

This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of the FCC rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:

• Reorientation or relocation of the receiving antenna.

• Connection of the equipment into an outlet on a circuit different from that to which the

receiver is connected.

• Consultation with the dealer or an experienced radio/TV technician.

EMC approvals

The EnviroSMART and EasyAG SDI-12 probes comply with “EN61326:1997 EMC standard for equipment for measurement, control and laboratory use”.

The equipment complies with the following specifications:

- EN55022/CISPR22 AS/NZS3548 Class B FCC Part 15 Class B.

- IEC1000-4-2

- IEC1000-4-3

- IEC1000-4-4

- IEC1000-4-5

- IEC1000-4-6

Marking

The above EMC approvals allow the product to be marked CE, C-tick and FCC.

Modifications

Any modifications to any part of the equipment or to any peripherals may void the EMC compliance of the equipment.

Radio Interference

The probe is not to be operated in free air as it may cause interference to radio communication devices

EnviroSMART & EasyAG SDI-12 Probe Manual

Table of Contents

The EnviroSMART® and EasyAG® SDI-12 Probe Interface.............................1

About the SDI-12 probe interface.......................................................................................................................1

What is SDI-12?.......................................................................................................................................................1

What are the EnviroSMART® and EasyAG® SDI-12 probe interfaces?...................................................1

What is the Intelligent Probe Configuration Utility?........................................................................................2

Setting the Probe Configuration....................................................................................................................2

SDI-12 Probe Interface.........................................................................................4

About setting up the EnviroSMART® and EasyAG® SDI-12 probe interface.........................................4

Why do I need to configure the SDI-12 probe interface?...............................................................................4

SDI-12 Communication........................................................................................5

About the SDI-12 Communication.....................................................................................................................5

Power Sequence.......................................................................................................................................................5

Timing.......................................................................................................................................................................6

Addresses..................................................................................................................................................................7

Data Reading............................................................................................................................................................8

Data Reading using the Start Measurement Command (aM! or aMn!)...................................................8

Data Reading using the Start Concurrent Measurement Command (aC! or aCn!).............................10

Identification..........................................................................................................................................................14

Supported Commands........................................................................................15

SDI-12 Commands Supported...........................................................................................................................15

Extended Commands Supported.......................................................................................................................16

EnviroSMART® Technical Specifications........................................................17

EasyAG® Technical Specifications...................................................................19

Circuit Information.............................................................................................21

Revision Information..........................................................................................22

EnviroSMART® Revision Information............................................................................................................22

EasyAG® Revision Information........................................................................................................................22

Appendix A – Soil Moisture Management.........................................................23

What soil volume does the SDI-12 probe interface measure at a single sensor?.......................................23

What are the water units?.....................................................................................................................................23

What part of the soil profile do multiple sensors on the probe measure?..................................................24

Appendix B – Salinity Management...................................................................25

EnviroSMART & EasyAG SDI-12 Probe Manual

Table of Figures

Figure 1: Intelligent Probe Configuration Utility software.........................................................................2

Figure 2: EnviroSMART® and EasyAG® SDI-12 probe interface communication power sequence........6

Figure 3: Voltage levels on the SDI-12 line during an Acknowledge Active command (a!)........................7

Figure 4: EnviroSMART® SDI-12 probe interface board layout.............................................................18

Figure 5: EasyAG® SDI-12 probe interface board layout........................................................................20

Figure 6: SDI-12 interface circuit diagram...............................................................................................21

Figure 7: TTL interface circuit diagram...................................................................................................21

Figure 8: EnviroSMART® SDI-12 probe interface old revision board layout..........................................22

Figure 9: Measurements using metric units..............................................................................................23

Figure 10: Measurements using imperial units.........................................................................................24

Figure 11: Measurements of multiple sensors on the probe......................................................................24

EnviroSMART & EasyAG SDI-12 Probe Manual

The EnviroSMART® and EasyAG® SDI-12 Probe Interface

About the SDI-12 probe interface

This section provides information about the EnviroSMART and EasyAG SDI-12 probe interfaces.

What is SDI-12?

SDI-12 (Serial Digital Interface at 1200 baud) is a standard communication protocol, allowing connection of multiple sensors to an SDI-12 compatible data logger. SDI-12 communicates using a cable containing three(3) conductors:

⇒ a serial communication line ⇒ a ground line ⇒ a 12V line

The EnviroSMART and EasyAG SDI-12 probe interfaces support commands from version 1.2 of the SDI-12 communication protocol. For more information on SDI-12, visit www.sdi-12.org.

What are the EnviroSMART® and EasyAG® SDI-12 probe interfaces?

The EnviroSMART and EasyAG SDI-12 probe interfaces are used to allow an SDI-12 compatible device to communicate with and retrieve data from multiple Sentek sensors installed on a single probe.

Both EnviroSMART and EasyAG SDI-12 probe interfaces behave as a slave device, meaning they are not capable of logging information or sampling data themselves. The interface must be attached to an SDI-12 compatible device acting as a master device, which will issue SDI-12 commands to instruct the probe interface what to do. When instructed to sample data, the SDI-12 probe interface will retrieve values from each sensor configured on the probe. These values are returned to the master device for storage.

The probe and its sensors are configured using the Intelligent Probe Configuration Utility (see section What is the intelligent Probe Configuration Utility?).

EnviroSMART & EasyAG SDI-12 Probe Manual

What is the Intelligent Probe Configuration Utility?

The Intelligent Probe Configuration Utility is provided to configure the EnviroSMART and EasyAG SDI-12 probe interfaces with depth location, normalization values (air and water counts) and calibration information for each sensor installed on the probe. This information is stored in non-volatile memory, and is used to produce the calculated value (value that has been processed via the interfaces calibration formula) from each sensor on the probe.

Communication between the Intelligent Probe Configuration Utility and the EnviroSMART and EasyAG SDI-12 probe interface is done using the Intelligent Probe Configuration Utility cable from a computers communication port to the probe interfaces TTL port.

Note: Temperature Sensors are currently not supported by the EnviroSMART and EasyAG SDI-12 probe interface.

Note: Information stored in non-volatile memory will not be lost when power is removed from the SDI-12 probe interface.

Figure 1: Intelligent Probe Configuration Utility software

Setting the Probe Configuration

Auto-detect Sensors

Auto-detect Sensors will detect all sensors currently installed on the probe. After the sensors are detected the configuration information (including type of sensor) will be displayed in the Probe Configuration list.

EnviroSMART & EasyAG SDI-12 Probe Manual

All sensor information must be valid before the configuration can be written to the probe.

Normalizing Sensors

Normalization is the setting of the range over which the sensor is effective. For example, soil moisture sensors have a range bounded by the 2 extremes, air and water. The normalization process is necessary to adjust for any variances that may occur during the production of the sensor.

Changing the Calibration Information

The sensor coefficients cell is used to store A, B and C coefficients. The coefficients are entered in A, B then C order, separated by semicolons.

Setting the SDI-12 Address

The address of the probe should be in the range “0” to “9”, “A” to “Z” and “a” to “z”.

EnviroSMART & EasyAG SDI-12 Probe Manual

SDI-12 Probe Interface

About setting up the EnviroSMART® and EasyAG® SDI-12 probe interface

This section provides information on setting up the EnviroSMART and EasyAG SDI-12 probe interfaces.

Why do I need to configure the SDI-12 probe interface?

The EnviroSMART and EasyAG SDI-12 probe interface must be configured to ensure valid information is reported to the data logger when data is requested. This information includes the number of sensors, normalization values (air and water counts) and calibration information.

By default, each SDI-12 probe interface is supplied with an SDI-12 address of “0”. If multiple probes are to be installed on an SDI-12 bus, each SDI-12 probe interface must be assigned a unique address (see section Addresses).

Warning!

Incorrect configuration information stored in the EnviroSMART or EasyAG SDI-12 probe interface will result in incorrect volumetric water content (mm/10cm) readings being reported to the controlling device.

For more information on setting up the EnviroSMART and EasyAG SDI-12 probe interface, refer to the Intelligent Probe Configuration Utility online help.

+ 21 hidden pages

Campbell Scientific AG SDI-12 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual