Large Water Utility Systems

Application Requirements – Extended DNP Point Processing
The standard RTU32M firmware does not include the extended DNP point processing functionality that was developed for large UK and Australian Water Utilities by Serck Controls for use in the eNET/SCADAPack ES RTUs.

However, the Brodersen WorkSuite software tools include a range of functions and function blocks that allow RTU32M programs and user defined function blocks (UDFBs) to be developed that provide the required extended point processing functionality – in a more ‘visible’ format.  ie. the code is not hidden/embedded in base firmware that only Brodersen can change…

Analog Point Processing Example:  The RTU32M is set to loop through its analog points in turn every 10ms to update the associated DNP3 point.  The analog point processing program includes logic that manages;

• scaling to EGU values
• point quality – online, comms lost, out of range and timestamp of last change.  Timestamps with 1ms resolution and module status are read directly from the AI module (for physical AI points).
• alarm limit processing (4x high, 4x low, under range and over range) plus daily and weekly profiles that allow each limit to be different at various times of the day
• persistence in and out of alarms (delay periods)
• dead band (3 modes – absolute, percentage and integration)
• alarm/event logging and unsolicited reporting
• interlocks for AO points (inhibit control)
• logging of configuration changes.

Binary Point Processing Example:  The RTU32M is set to loop through its binary points in turn every 10ms to update the associated DNP3 point.  The binary point processing program includes logic that manages;

• debounce and state inversion
• point quality – online, comms lost and timestamp of last change.  Timestamps with 1ms resolution and module status are read directly from the DI module (for physical BI points).
• alarm state processing (includes alarm severity)
• persistence in and out of alarms (delay periods)
• alarm/event logging and unsolicited reporting
• interlocks for BO points (inhibit control)
• logging of configuration changes.

Trend Point Processing Example:  The RTU32M is set to loop through its trend points in turn every 1s to determine if it is time to update the trend sample point (a structured tag with multiple attributes, that is set to generate events, but is not included in Class 0 polls) ie. trend samples are simply additional DNP3 events, rather than stored values in log files that need to be uploaded/processed separately by the SCADA Host.  The trend point processing program includes logic that manages;

First Sample Rate – if the is point due for update

• Analogs – stores current value, AVG, MIN, MAX and DELTA
• Counters – stores current value and DELTA
• Binarys – stores current value only

Second Sample Rate – if the is point due for update

• Analogs – stores current value
• Counters – stores current value 
• Binarys – stores current value only

Log Period – if the point is due to be logged, trigger an event recording for the required ‘stream’

Logging of configuration changes.

Application Requirements – DNP3 points with extra attributes

The standard DNP3 setup in the Brodersen RTUs is well suited to typical applications in the water and power industry where DNP3 is the predominant protocol.  The table below shows the 12 parameters/attributes that a ‘generic’ analog point uses to define its type, number, event class, threshold mode and event deviation amount.