Frequently Asked Questions
A tick list of features could be used for discussion.
This high level of data communication can slow things down when using GPRS or GSM.
WITS and the DNP3 standard
WITS uses DNP3 Object Group 0 to provide asset management and interoperability of Field Devices through device identification (based on product manufacturer name, device type etc.). In particular WITS defines 2 attribute sets, the standard index 0 and a WITS attribute set.
standard DNP3 set
state change events – Analogue Events, Counter Events, Binary Events
application program management
DNP3 File transfers are used to acccess Field Device log files, which store timestamped historical data. DNP3 File transfers are also used to provide Incremental configuration updates to Field Devices through a WITS defined file format.
WITS Founder Vendors
ITT Waste & Wastewater (now Xylem)
Serck ( now also Schneider Electric )
NB: Metasphere were involved in the early design stages
Developing a device
The actual development process and tools are for the vendor to determine. A DNP3 stack is available from Triangle Microworks which is used by some vendors as the basis of their WITS device, while others have developed an in-house stack – either is acceptable as the only criteria is to demonstrate successful testing to the WITS standard.
Here is a most useful guide for vendors entitled “Steps to consider in implementing a WITS Field Device” – click here.
This can be achieved by have a setting within the Field Device that defines which version of the standard it will use (this could be stored within the Bulk Configuration File) or alternatively by having different firmware versions for different versions of the standard.
In addition the Field Device must have an XML device profile for each version of the standard that it supports. To facilitate this the latest WITS Document Pack includes the device profiles files for every released version of the WITS standard. The device profiles for each supported version of the standard should be included with your WITS verified or self-certified application.
In addition the Master Station must have an XML device profile for each version of the standard that it supports. To facilitate this the latest WITS Document Pack includes the device profiles files for every released version of the WITS standard. The device profiles for each supported version of the standard should be included with your WITS verified or self-certified application.
Testing a device
The WITS Test Specification is available to purchase from the PSA Secretary.
Note that two WITS Master Station vendors offer a “test licence” enabling vendors to use the Master Station software to assist vendors in testing their Field Device (see web site News item – 4-Nov-2014 Test Master Station Software Now Available)
On Thames for example, the first products underwent full verification but later products may be Self Certified now that confidence has been established with the client user.
Device compliance to the WITS standard
WITS Verified – The vendor must prove product interoperability by testing the Field Device or Master Station against products from a separate development entity to ensure a higher level of assurance.
WITS Self-certified – Tests will be conducted by the vendor themselves using an appropriate test harness / simulator, WITS Field Device or WITS Master Station.
The implications of following these two paths are described in detail in “How to achieve self certified and verified status“, however, it is recommended that new products wishing to claim WITS-DNP3 compliance follow the Verified status route.
However, Field devices must be 1.3 compliant
Registering a device
For a Master Station, the signatures of the three Field Device vendors plus the Master Station vendor.
The PSA’s Role
- Access to Application Notes
- Access to Compliance Testing Manual
- Access to Device Profiles
- Access to members only sections of website
- Access to listing of certified products
- Use of WITS-DNP3 logo on certified products
- Election and nomination rights to the Protocol Standards Association Committee
- Voting rights at Meetings
- Product features on website
- Hyperlink to member’s website
Download a Corporate Membership form by clicking on the link on the page Complete and sign it Send it to the WITS PSA Secretary at the address on the form with your cheque
scan and email it to firstname.lastname@example.org if you prefer to pay by bank transfer (bank details are on the form). The applicant will then be registered as a Member on the website.
For additional persons from your organisation who wish to become Members and access the Members-only pages, download an Additional Membership form from the “Join now” page, complete and sign it and scan/email or post it to the WITS PSA Secretary. There is no fee for additional members.
The PSA Committee
See the PSA Constitution for more details.