Message-Based Communications for Pipeline SCADA Stephen Koenig, P.E. Smarter Infrastructure for Oil and Gas December 3, 2013 Houston, TX source:

source:

source: Data stored in the meter station Flow Computer Sensor Data Data stored in the Corporate Accounting System Data calculated by meter station Flow Computer

Messaging - Basic Concepts Multiple data sources (publishers) send messages to multiple data destinations (subscribers) Destinations subscribe by “topic” Payload can be anything: text, binary, fixed fields, etc up to 250Mbytes in size Broker supports multiple delivery options (QoS) Data Destination Data Source Network Message Broker Data Source Data Destination Publish Subscribe Message Format Topic Payload

Automation to Support Pipeline Operations F TP Flow Computer Remote Terminal Unit Comm Processor Tank Gauging System Satellite Link to Control Center

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source: API RP 1165 – Recommended Practice for SCADA Displays

Traditional Approach to SCADA Poll/Response Host & RTU ’ s are serial devices – typically Programmable Logic Controllers “ Round Robin ” polling Data format optimized for mininimum overhead

Problems with Poll/Response systems Host “ owns ” communications link Dedicated circuits are too expensive Alarm latency increases with RTU count

Evolution to Message-Based Communications Step 1

Evolution to Message-Based Communications Step 2

Evolution to Message-Based Communications Step 3

Evolution to Message-Based Communications Step 4

Challenges in Use of Message-Based Communications for SCADA Controls – limited life in system Stale Data – replace poll/response functionality in event-driven system Security – Flexible architecture may result in new vulnerabilities – Message-based system must be as secure as traditional poll/response – Need for continuous improvement

Benefits of Message-Based Approach to SCADA Topic/Payload Message Structure IP Routing Intelligent Front-End Processor Many-to-Many Architecture

Benefits - Topic/Payload Message Structure “ Wildcard ” subscriptions Support for multiple applications on one message broker Use of version number in topic - Facilitate prototype and test of new clients - Allows site-by-site migration strategy

Benefits – IP Routing Scalability

Benefits – IP Routing -- Redundancy Reducing the Impact of Failure Provisions for broker equipment failure Provisions for loss of primary communications link – backup link Broker1 Broker2 Broker3 Broker4

Benefits – Intelligent Front-End Processor Adapt Serial Devices to IP/VSAT Move polling/response to field Ability to handle multiple RTU protocols Local intelligence can supplement or enhance control system Broker1 Broker2 Broker3 Broker4

Benefits – Many-to-Many Architecture Significantly reduced project schedules Off-line systems receive live data for testing

Future Opportunities for Message-Based SCADA Systems (from a 2005 perspective) “Flight Simulator” for pipeline Controllers Interface to business systems Real-time meter ticket transactions to shippers and other carriers’ business systems Distributed SCADA