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December 3, 2019

I am preparing a summary of the past year. It will be posted here soon, after a review by the Board of Directors.

Mike Jablonski, SDI-12 Support Group Chairman

September 30, 2019

The Board of Directors for the SDI-12 Support Group has decided not to have our annual meetings this year at the American Water Resources Association's annual conference in Salt Lake City, Utah. This is because there are no technical issues or proposed changes to the SDI-12 Specification before the Support Group.

The Board of Directors will, however, review and document all Support Group activities over the past year, publishing that information on this web site in November.

February 19, 2019

Minutes taken at the November 5 and 6, 2018, SDI-12 Support Group meetings are now available:

January 10, 2019

Added a sentence to Table 5, The SDI-12 basic command/response set, on page 8, so that references to all SDI-12 commands are included on page 8:

“See Tables 12 and 13 for the high-volume commands (pages 24-25), Table 19 for the identify measurement commands (page 29), and Table 20 for the identify measurement parameter commands (page 32).”


SDI-12 remains at version 1.4.

December 16, 2018

Upgraded this website, making it friendly for mobile devices.

October 22, 2018

The Technical Committee Meeting of the SDI-12 Support Group will be on Monday, November 5, 2018.
The General Meeting of the SDI-12 Support Group will be held on Tuesday, November 6, 2018.
The meetings will be at the annual conference of the American Water Resources Association (AWRA). Each meeting will start at 8:30 A.M.

Both meetings will be held at the Marriott Inner Harbor at Camden Yards, Baltimore, Maryland. The meetings will be in the Ravens room on the lobby level of the hotel.

All interested parties are welcome to attend the meetings.

Agenda, Technical Committee (Monday, November 5, 2018)
  1. welcome and introductions
  2. review of concerns and comments about SDI-12 received over the last year by users and/or manufacturers of SDI-12 devices
  3. review of any suggested changes to the SDI-12 Specification that any members of the technical committee are aware of, including any errors or omissions in the SDI-12 Specification
  4. discussion about the use of the high-volume data commands and metadata commands added to SDI-12 version 1.4
  5. review of website
  6. review of website traffic
  7. Discussion, led by Gerald Kunkle, U.S. Geological Survey (USGS), Hydrologic Instrumentation Facility (HIF) about the upcoming DATC (Data Acquisition, Telemetry, and Control) project for the USGS Water Mission Area. The goal of the project is to modernize the entire USGS water data pipeline, including sensor communication, telemetry, and database software. (Gerald is on the SDI-12 Support Group’s Technical Committee.)
  8. open discussion about SDI-12
  9. discuss and list the names of those that wish to serve on the SDI-12 Support Group's Technical Committee for the next year, including the addition of any new volunteers, for presentation at the General Meeting of the Support Group (on Tuesday, November 6)
Agenda, General Meeting of the SDI-12 Support Group (Tuesday, November 6, 2018)
  1. welcome and introductions
  2. report about the Technical Committee meeting, as held on November 5, 2018
  3. financial report and discussion on the collections of membership dues
  4. selection of Chairman and Board Members for the upcoming year
  5. formally select and renew members of the Technical Committee for the upcoming year
October 1, 2018

The SDI-12 Support Group will hold its annual meetings this year on November 5 and 6. These meetings will be held at the annual conference of the American Water Resources Association (AWRA), in Baltimore, Maryland.

The SDI-12 Support Group’s Technical Committee will meet on Monday, November 5. The general meeting of the Support Group will be on Tuesday, November 6. An agenda for each meeting will be posted soon.

The conference will be at the Baltimore Marriott - Inner Harbor at Camden Yards

All interested parties are welcome at the meetings.

February 5, 2018

You may now pay your Support Group Dues ($300) via PayPal, using this email address: .

We can also accept dues payments via credit card.

January 5, 2018

Minutes taken at the November 6 and 7, 2017, SDI-12 Support Group meetings are now available:

December 1, 2017

Made internal formatting changes in the SDI-12 Specification, adding bookmarks for Portable Document File (PDF) readers to quickly see and go to specific sections. Changed the date on the document to December 1, 2017.

No other changes or clarifications were made to the specification.

October 19, 2017

The Technical Committee Meeting of the SDI-12 Support Group will be on Monday, November 6, 2017.

The General Meeting of the SDI-12 Support Group will be held on Tuesday, November 7, 2017.

The meetings will be at the annual conference of the American Water Resources Association (AWRA). Each meeting will start at 8:30 A.M.

Both meetings will be held in the Jantzen Room at the Red Lion Hotel on the River- Jantzen Beach in Portland, Oregon.

All interested parties are welcome to attend the meetings.

Agenda, Technical Committee (Monday, November 6, 2017)
  1. welcome and introductions
  2. discussion about the acceptance of SDI-12 version 1.4: metadata commands, high volume ASCII command, and the high volume binary command, by the SDI-12 community
  3. comparison of the timing throughput using the version 1.4 binary commands, compared to the version 1.3 ASCII data transfer commands, in cases in where both the ASCII and high volume binary commands could both be used to transfer a small number of parameters from a sensor to a data recorder
  4. discussion on the programming effort to implement the version 1.4 commands, metadata and high volume, based on the experience of all present that have added support to version 1.4 for their company's products
  5. review of website
  6. review of website traffic
  7. discuss and list the names of those that wish to serve on the SDI-12 Support Group's Technical Committee for the next year, including the addition of any new volunteers, for presentation at the General Meeting of the Support Group (on Tuesday, November 7)
Agenda, General Meeting of the SDI-12 Support Group (Tuesday, November 7, 2017)
  1. welcome and introductions
  2. review of the Technical Committee meeting, held on November 6
  3. financial report and discussion on the collection of membership dues
  4. selection of Chairman and Board Members for the upcoming year
  5. formally select and renew members of the Technical Committee for the upcoming year
September 27, 2017

The SDI-12 Support Group will hold its annual meetings this year on November 6 and 7. These meetings will be held at the annual conference of the American Water Resources Association (AWRA), in Portland, Oregon.

The SDI-12 Support Group’s Technical Committee will meet on Monday, November 6. The general meeting of the Support Group will be on Tuesday, November 7. An agenda for each meeting will be posted soon.

The conference will be at the Red Lion Hotel on the River- Jantzen Beach in Portland, Oregon.

All interested parties are welcome at the meetings.

May 1, 2017

Corrected numerous mistakes, and one omission, in the Version 1.4 SDI-12 Specification, dated August 8, 2016. The corrected document remains at version 1.4, dated May 1, 2017.

  1. Page 10, Table 7, the send identification command, had numerous typographic errors and omissions, introduced when SDI-12 was upgraded from version 1.3 to version 1.4. Restored the content in the table to its original condition, correcting the errors.
  2. Page 32, Section 6.2.4, examples of the identify measurement parameter commands: example (a) and example (c) were missing the letter “I” in the command. Added the letter “I”.
  3. Pages 31 and 32, Table 20, the identify measurement parameter commands, column two was missing <CRC> for the measurement commands that return a CRC. It said:

    a,field1,field2;<CR><LF>

    rather than:

    a,field1,field2;<CRC><CR><LF>

    Added <CRC> for all of the measurement commands that return a CRC.
  4. Page 28, Section 5.4, Compliance with High Volume Command, omitted stating what the required response is, to the aHA! and aHB! commands, for sensors that do not support the high volume commands. Added the following paragraph to correct this omission, as the same requirement is imposed on the other measurement commands.
  5. “Version 1.4 sensors that do not support the high volume ASCII command, or the high volume binary command, should respond with a000000 CR LF saying that it has zero data values ready.”
  6. Appendix A-1, Suggested SDI-12 Circuits, had the same label for both circuits. Restored the label for the bottom circuit to:
    “sensor or data recorder interface circuit with transient protection”
September 19, 2016

After upgrading the SDI-12 Specification, releasing version 1.4 in July, the technical committee has decided that a meeting this year is unnecessary. We want to wait and see how the new additions to the specification, (high volume ASCII, high volume binary, metadata commands) are accepted before holding our next meeting.

For your information, if you want to attend the AWRA conference this year, it will be in Orlando, Florida on November 13-17. Click here for more information. We greatly appreciate AWRA for providing us with meeting rooms each year, since 1992, at their annual conference.

August 10, 2016

Corrected an error in the SDI-12 Specification: Page 27, Table 17 Data values in the high volume binary command, Rows 1 and 2, Column 2, incorrectly said "Signed-32 bit integer" rather than "Signed-16 bit integer."

July 14, 2016

Version 1.4 of the SDI-12 Specification is ready. This adds four additions to SDI-12, as listed below, in the announcement dated April 25, 2016.

April 25, 2016 Voting Results

Voting on the four proposed additions to the SDI-12 Specification ended on April 15, 2016. The voter turnout was 100% of the membership of the Support Group, with 14 companies/agencies submitting votes.

Under the bylaws of the SDI-12 Support Group, a two-thirds majority of returned ballots is required to accept a change to the SDI-12 Specification. All four proposed additions received more than a two-thirds majority. Therefore, the proposed additions will be added to the SDI-12 Specification and integrated into the formal SDI-12 Specification as soon as possible.

The four additions are:

  1. Identify Measurement Commands
  2. Identify Measurement Parameter Commands
  3. Start High Volume ASCII Measurement
  4. Start High Volume Binary Measurement

Details about the four additions to the SDI-12 Specification are here:

March 1, 2016 Newsletter with Proposed Additions to the SDI-12 Specification

The Technical Committee has released a document on four proposed additions to the SDI-12 Specification, as discussed at the November 16 meeting. Voting on these proposed additions will be open starting on March 16 and ending on April 15 (30 days).

Ballots will be issued on March 15.

Details are in the newsletter, dated March 1.

February 10, 2016

Minutes taken at the November 16 and 17, 2015, SDI-12 Support Group meetings are now available:

January 28, 2016

A revised version of the SDI-12 Specification is ready. The version number is still 1.3 because clarifications only were made to the specification.

The clarifications are:

  1. Page 26, Section 5.2. Added “CRC error“ to the first sentence of the last paragraph as one of five invalid response conditions, from a sensor, that require a data recorder retry.
  2. Page 26, Section 5.2. Deleted the word three in the sentence, “If one of the above three conditions exists the data recorder will issue retries.“
  3. Appendix B-2, SDI-12 Sensor Flow Chart. Added “set data line to marking for 8.33 ms“ to the box between “valid command?“ and “more processing?“ This clarifies the supporting text on page 24, Section 5.0, which says, “After receiving the break and the command, the addressed sensor sets the data line to marking for 8.33 milliseconds and then sends the response.“
  4. Appendices B-1 and B-2, SDI-12 Data Recorder Flow Chart/SDI-12 Sensor Flow Chart. Changed all instances of “msec“ to the correct abbreviation of “ms.“
October 23, 2015

The SDI-12 Support Group will hold our annual meetings this year on November 16 and 17. We will meet in conjunction with the annual American Water Resources Association (AWRA) conference. The AWRA conference is scheduled for November 16-19, at the Grand Hyatt in Denver, Colorado.

Both meetings will be in the Mt. Harvard Room, on the 3rd floor of the Grand Hyatt (above the lobby in the main hotel, not the conference center).

All are welcome to attend.

Click here to learn more about the AWRA conference and the venue for the SDI-12 meetings.

Monday, November 16, 9:00 A.M., Technical Committee Meeting

  1. Welcome and Introductions
  2. Preliminary discussion with the USGS/Hydrologic Instrumentation Facility (HIF) about the possibility of a new standard
    This standard would have the following minimum requirements:
  3. Higher bandwidth communication for collecting large amounts of data from sensors like Acoustic Doppler Current Profilers (ADCPs) and water quality sondes.
  4. Plug-and-play sensor capability to allow two compatible devices to automatically recognize each other and communicate. For example, when a sensor is plugged into a data logger, the logger would be able to recognize the sensor and configure itself as needed to log data from the sensor.
  5. This new interface would include most existing SDI-12 features, including the standard command set and a low-power sleep mode.
  6. Discussion on a proposed clarification to the SDI-12 Specification:

    Add text to the sensor flow chart to explicitly state that a sensor must set the data line to marking for 8.33 milliseconds before sending the response, to be in agreement with section 5.0, Timing, which says "After receiving the break and the command, the addressed sensor sets the data line to marking for 8.33 milliseconds and then sends the response."

  7. Open discussion about the SDI-12 specification
  8. Reinstatement of the Technical Committee for the upcoming year
Tuesday, November 16, 9:00 A.M. General Meeting

  1. Welcome and Introductions
  2. Review of the technical committee meeting
  3. of visitor statistics on www.sdi-12.org
  4. Financial Report
  5. Selection of Chairman and Board Members for the upcoming year
August 28, 2015

The SDI-12 Support Group will be holding our annual meetings in November. We will meet in conjunction with the annual American Water Resources Association (AWRA) conference. The AWRA conference is scheduled for November 16-19, at the Grand Hyatt in Denver, Colorado.

The Technical Committee will meet on Monday, November 16. The general meeting of the SDI-12 Support Group will be on November 17.

Full agendas for both meetings will be published soon.

The USGS/Hydrologic Instrumentation Facility (HIF) would like to hold a brief preliminary discussion about the possibility of a new standard at the technical committee meeting.

This standard would have the following minimum requirements:

  1. Higher bandwidth communication for collecting large amounts of data from sensors like Acoustic Doppler Current Profilers (ADCPs) and water quality sondes.
  2. Plug-and-play sensor capability to allow two compatible devices to automatically recognize each other and communicate. For example, when a sensor is plugged into a data logger, the logger would be able to recognize the sensor and configure itself as needed to log data from the sensor.
  3. This new interface would include most existing SDI-12 features, including the standard command set and a low-power sleep mode.

Click here to learn more about the 2015 AWRA conference.

January 30, 2015

Posted a newsletter:

Minutes taken at the November 3 and 4, 2014, SDI-12 Support Group meetings are now available:

January 1, 2015

We are now accepting dues for 2015.

October 20, 2014

The SDI-12 Support Group will hold our annual meetings this year on November 3 and 4. The meetings will be held at the 2014 Annual AWRA conference at the Sheraton Premier Hotel, in Tyson's Corner, Virginia. Tyson's Corner is adjacent to Washington, D.C.

The meetings will be in the Rappahannock Room which is on the main lobby level of the hotel.

All are welcome to attend.

Click here to learn more about the AWRA conference and the venue for the SDI-12 meetings.
Monday, November 3, 9:00 A.M., Technical Committee Meeting (the room number will be posted when it's available)

  1. Welcome and Introductions
  2. Review of the written history of SDI-12
  3. Review of text about SDI-12 to post on www.Wikipedia.org
  4. Open discussion about the SDI-12 specification
  5. Reinstatement of the Technical Committee for the upcoming year
Tuesday, November 4, 9:00 A.M. General Meeting (the room number will be posted when it's available)

  1. Welcome and Introductions
  2. Review of the technical committee meeting
  3. Review of visitor statistics on www.sdi-12.
  4. Financial report
  5. Report on the corporate standing of the SDI-12 Support Group with the State of Utah and the IRS (there are no problems).
  6. Discussion on how to better collect dues from the current and past membership of the Group
  7. Open discussion on SDI-
  8. Selection of Chairman and Board Members for the upcoming year
September 22, 2014

The SDI-12 Support Group will hold our annual meetings this year on November 3 and 4. The meetings will be held at the 2014 Annual AWRA conference at the Sheraton Premier Hotel, in Tyson's Corner, Virginia. Tyson's Corner is adjacent to Washington, D.C.

January 14, 2014

Dues for 2014 are now due.

October 14, 2013

The SDI-12 Support Group will not be holding annual meetings this year at the American Water Resources (AWRA) conference. This is because there are no pending technical issues or proposed changes to the SDI-12 Specification. Our next meeting is planned for 2014 at the AWRA conference in Washington, D.C.

January 26, 2013

A revised version of the SDI-12 Specification is ready. The version number is still 1.3 because clarifications only were made to the specification.

The clarifications are:

  1. Page 1, Section 1.0. Added “see section 3.0 for details” to the third bullet.
  2. Page 1, Section 1.0. Deleted the fourth bullet, “Up to 200 feet of cable between a sensor and data recorder.”
  3. Page 11, Table 9. Made a correction. Changed “a valid range of 0 to 9" to “a valid range of 1 to 9" in row 3, column 2.
  4. Page 14, Table 10. Deleted this text, “(a data recorder must be able to read and store at least 20 parameters from a sensor, nn = 20)”
  5. Page 14, Section 4.4.7. Deleted this text, “The maximum number of data values a sensor can return for nn is 20. A data recorder is also required to store 20 values. Future versions of SDI-12 may increase this to a maximum of up to 99 values.”
  6. Page 14, Section 4.4.7. Added this text, “The data recorder should document the number of data values it can store in response to a C command.”
  7. Page 14, Section 4.4.7. Changed the last paragraph from:

    See the send data command, aD0!, aD1! . . . Ad9! for examples of this command. Because the start concurrent measurement command is closely related to the send data command, examples for both commands are in sections 4.4.8.3 and 4.4.8.4.

    To:

    “See the send data command, aD0!, aD1! . . . aD9!, section 4.4.8, for the data response requirements. Because the start concurrent measurement command is closely related to the send data command, examples for both commands are in sections 4.4.8.3 and 4.4.8.4.”
  8. Page 14, Section 4.4.8. Change the paragraph heading from “aD0! ... aD9!” to “aD0!, ...aD1 ... aD9!.”
November 19, 2012

Minutes taken at the November 13 and 14 SDI-12 Support Group meetings are now available:

October 30, 2012

Click here for the agendas for the technical committee meeting (November 12) and the general meeting of the SDI-12 Support Group (November 13).

October 26, 2012

Here is a list of the technical issues which will be discussed at the upcoming meeting of the Technical Committee. This meeting will held on November 12. This meeting will be held in Jacksonville, Florida, in conjunction with the American Water Resources Association (AWRA) conference, at the Hyatt Regency Jacksonville Riverfront.

A formal agenda for the Technical Committee meeting (November 12) and the general meeting (November 13), will be posted here during the week of October 28).

Clarifications of existing specification
  1. The current specification requires support of aC! command with something other than zero parameters, but no such explicit requirement for the aM! command. Does explicit support of aM! need to be specified?
  2. Clarification of section 1.0. Should the line mentioning 200 feet be removed? Or reworded in some way? Section 1.0 is seen before 3.0 leaving the impression that SDI-12 only works up to 200 feet.
  3. Add an appendix or other text to provide installation guidance to users about an acceptable SDI-12 cable length for their systems.
Enhancements to the specification
  1. Remove the 20 limit for nn for the maximum number of parameters that can be returned from the C series of commands.
  2. If the limit of 20 is removed from the sensor response, do any changes need to be made to the data recorder requirements?
    1. Left the same
    2. Increased
    3. Explicit data recorder requirement eliminated.
  3. Adding a means to return parameter labels/codes and/or units.
  4. Adding a means to support sensor contained documentation of commands.
October 2, 2012

We will hold our annual meetings this year on November 12th and 13th. These meetings will be held in Jacksonville, Florida, in conjunction with the American Water Resources Association (AWRA) conference, at the Hyatt Regency Jacksonville Riverfront.

The technical committee will meet on Monday, November 12.

The business meeting of the SDI-12 Support Group will be held on Tuesday, November 13.

All interested parties are welcome to attend.

Agendas for each meeting will be posted here soon.

You can learn more about the AWRA conference and the meeting venue at: www.awra.org

May 4, 2012

I have the sad and heartbreaking duty of telling you that Paul-Émile Bergeron, a long time member of the SDI-12 Support Group's technical committee and supporter of SDI-12, died suddenly on April 28. Mr. Bergeron has been an active member of the Support Group since the early days of SDI-12 in the mid 90s. He commented vigorously on each and every proposed change to SDI-12 over the years. We could always count on Paul-Émile to express a never ending stream of ideas to improve SDI-12. We enjoyed his presence at our annual meetings.

The SDI-12 Support Group will make a contribution to Camp Cherith to honor our friend.

Michael Jablonski
Chairman, SDI-12 Support Group

His obituary follows:

BERGERON, Paul-Émile
Employee of Environment Canada

Suddenly in Terrace, British Columbia on Saturday April 28th, 2012 at the age of 53. Dear son of the late Marie-Anne Beaudoin and the late Léo-Paul Bergeron. Beloved soulmate of Micheline Fleming. Loving brother of Marcel (Alice Lemay), Françoise (René Boudreau), Nicole (Michel Dupras), Marie-Antonia (Denis Rhéaume), Jacinthe (Marcel Bédard), Christian (Joanne Charest), René (Lyne Rousseau), Rosane (Richard Labrecque), Claude, Jean-Louis (Ghislaine Allaire), Sylvain (Christine Gilbert), Johanne (André Doyon), Isabelle (Lionel Blais) and Serge (Solange Joncas). Fondly remembered by his goddaughter Audrey Bergeron, godson René-Paul Bergeron and his nieces and nephews. Pre-deceased his brother Léon.

Friends are invited to visit at the St.Laurent Chapel of Hulse, Playfair & McGarry 1200 Ogilvie Road (at Aviation Parkway) on Sunday May 6th, 2012 from 1 pm until the Liturgy of the Word in the Chapel at 3 p.m. A funeral Mass will be held in Saint-Flavien, Quebec. In lieu of flowers, memorial contributions to the University of Ottawa Heart Institute Foundation 40 Ruskin Street, Room H2408 Ottawa, Ontario K1Y 4W7 or to the Camp Cherith, 286 River Farm Lane, RR#4 Lanark, Ontario K0G 1K0 or on line www.cherith.ca would be appreciated by the family.

Februrary 24, 2012

A complete refresh of the SDI-12 Support Group's web page has been completed and released.

January 9, 2012

Each year the SDI-12 Support Group holds its annual meetings in conjunction with the American Water Resources Association (AWRA) conference. This year the conference will be in Jacksonville, Florida on November 12-15, 2012. Meeting agendas will be posted at least 30 days in advance of the meetings. All are welcome to attend.

January 3, 2012

A revised version of the SDI-12 Specification is ready. The version number is still 1.3 because clarifications only were made to the specification.

The most significant revision is a correction on the SDI-12 Sensor Flow Control diagram in appendix B. It was changed so that the logic for the concurrent command matches the text in the body of the specification.

The clarifications are:

  1. Page 5, Section 4.0. Reference to page 14 changed to reference to section 4.4.7
  2. Page 12, Section 4.4.5.1. Deleted the sentence, “It must also empty its buffer so that no data are returned in response to a D command.” This sentence was deleted because the sentence after it specifically states what information is to be returned to the sensor in response to subsequent D commands.
  3. Page 14, Section 4.4.7.1. Deleted the sentence, “It must also empty its buffer so that no data are returned in response to a D command.” This sentence was deleted because the sentence after it specifically states what information is to be returned to the sensor in response to subsequent D commands.
  4. Page 16, Section 4.4.8.3. Reference to section 4.4 changed to section 4.4.8.
  5. Page 16, Section 4.4.8.3. Circular reference to section 4.4.8.3 changed to section 4.4.8.4.
  6. Page 23, Section 4.4.13. Corrected typographical error. Deleted the letter s from “extendeds.”
  7. Formatted all paragraph headings in bold.
  8. Changed Appendix B, Suggested SDI-12 Flow Control for SDI-12 Data Recorded so that the logic for the concurrent command matches the text in the body of the document.
December 21, 2011

For several years the SDI-12 Support Group has made a yearly donation to the American Water Resources' (AWRA) Richard A. Herbert Memorial Education Fund. The SDI-12 Support Group has donated $700.00 to this scholarship fund. Our most recent donation of $100.00 was made on December 21, 2011.