About Stuart Combellack

Senior Software Engineer, Technolog Limited.

18-Jun-2017 New WITS Technical Bulletin TB#61: Clarification on Extended Data Points

Today, the WITS-PSA has published the results of our work to clarify some points within WITS-DNP3. The updated Technical Bulletin is as follows:

TB #61 – Clarifications on the use of Extended Data Points when there are no valid values of the source point.

In addition, the Technical Bulletin index has been updated to include this enhancement.

To download the updated documentation, log-in to the website to access the Members section. Then from the “Members” […]

09-Jun-2017 WITS Plugfest Report (May 2017)


There came a point in the development of the WITS-DNP3 protocol, many years ago, when we had to migrate from writing documents about the protocol and thinking about how it would work, to building and testing real devices. To do this we used plugfests. For WITS and many other organisations, a plugfest is a chance to bring various bits of equipment together and test that the interfaces between them all work as expected. […]

12-Jun-2017 Grundfos CIU 531 Field Device Profile

WITS Version 1.1 – Self certified on 12th June 2017


Note that this Device Profile shows the device’s functionality at the time it was listed as a self certified device. The vendor may have changed the device’s functionality since that time and they may have later versions of the Device Profile.
The device was tested to Test Specification version 3 Note that later versions of the Test […]

06-Jun-2017 WITS Membership Fee Changes

Simplified WITS Membership Fee Structure

From the inception of the WITS Protocol Standards Association we have recognised the massive contributions made by our Founder Members, and have reflected that in our scale of membership fees. However the Committee has decided that we need to rationalise the fees in order to simplify our accounts and in addition attract new members to the PSA by removing the registration fee for new members.

Therefore  from 6th June 2017  the […]

17-May-2017 WITS-DNP3 Plugfest – Today

Xylem is kindly hosting the #WITSPlugfest event at their Nottingham, England offices.

26 attending engineers, 9 Field Device manufacturers and 2 Master-Station developers.

Lots of very detailed discussions, scanning logs, sharing of information and ideas but most importantly: Testing!  By the end of the day we will have improved the quality and reliability of the WITS-DNP3 protocol and learned a great deal about each other’s systems and products.

Plug-Fests are a great way to bring everyone together […]

04-May-2017 Cyber Security Briefing on 18th May

Cyber Security Meeting for OT/IoT: UK and US Experiences, May 18th 2017

As members of the WITS PSA you may wish to consider attending this briefing on Cyber Security for OT/IoT. The briefing is to be held in London on Thursday 18th May 2017. The briefing is hosted by Tech UK and includes speakers from the Department for Culture, Media and Support, the Department for Homeland Security, ARM and the IoT Security Foundation. For those with […]

03-May-2017 DNP3 TB2016-005 information for WITS members

The publication

The DNP User Group published the following news on December 28th 2016:

The DNP Technical Committee has released the following Technical Bulletin (TB):

  • TB2016-005 Indicating Invalid Floating-point Data in Object Group 0 Variations

TB2013-004 introduced some new Object Group 0 Variations that are used to report GPS data from an outstation (latitude and longitude). Questions arose about how an outstation should use these objects if it cannot get a GPS fix to the required number […]

03-May-2017 DNP3 TB2016-004 information for WITS members

The publication

The DNP User Group published the following news on December 2nd 2016:

The DNP Technical Committee has released the following Technical Bulletin (TB):

  • TB2016-004 Updated Unsolicited Reporting Requirements for Constrained Environments

The TB (dated November 29th 2016) makes minor changes to the DNP3 specification, describing that outstations may not always be able to communicate “immediately” due to constraints outside of the DNP3 protocol.

How does this affect WITS users?

This has no impact on WITS users.

How does […]

18-Jan-2017 Anglian Water now LIVE with WITS

Anglian Water are pleased to announce that the first Anglian Water WITS outstation (Servelec S2000 Micro) went live on their Schneider ClearSCADA  telemetry master station in December 2016.

They had a small but dedicated team of internal engineers supported by Servelec, and Mark and Neil from Terzo Digital working extremely hard to get them to this position.

The team went though a steep learning curve and in the spirit of co-operation and sharing knowledge they will […]

04-Jan-2017 New WITS Technical Bulletins Published (TBs 56-60)

Today, the WITS-PSA has published the final results of many months of work, standardising some important new features into WITS-DNP3.  These include recommendations for operating WITS-DNP3 in an optimised manner and transients recording (high speed recording and triggering data send after an incident condition).  The updated Technical Bulletins are as follows:

TB #56 – Defining how to use WITS-DNP3 in an optimised manner.

TB #57 – Adding incident logs and significant change logs (transients recording).

TB #58 – […]