SCADA Communication and Architecture Principles Mark Scantlebury, P. Eng., BASc. President and CEO 11/21/2018

Overview SCADA System Basics Field Communications Modbus Protocol Hazardous Locations Field Architectures © Extreme Telematics Corp. 2013 11/21/2018

SCADA Supervisory Control And Data Acquisition General term for a system used to control and collect data from a set of remote devices. Many choices for system architecture, types of devices, and communication protocols. Concepts are simple, but systems can get complex. Will discuss most popular systems used for oil and gas. © Extreme Telematics Corp. 2013 11/21/2018

System Overview © Extreme Telematics Corp. 2013 11/21/2018

Field Devices Many Different Types of Devices RTU – Remote Terminal Unit PLC – Programmable Logic Controller Application Specific – i.e. Flow Computer Responsible for Monitoring Local Sensors and Providing Control Current Values Made Available Some History Stored © Extreme Telematics Corp. 2013 11/21/2018

Servers Communication Driver Retrieves Data From Remote Devices Historian is a database that stores multiple historical values for a specific tag (value from a device). HMI – Human Machine Interface is the set of screens made available to client devices. Multiple items may be combined © Extreme Telematics Corp. 2013 11/21/2018

Clients Many different types of client devices Thick (installed) or thin (web) client interfaces Can be connected to the network locally or remotely Access always goes through the server © Extreme Telematics Corp. 2013 11/21/2018

Field Communications Many choices for communicating with RTUs/PLCs in the field Allows the server to get information from each device Most likely a polled architecture Data can be sent from end devices Modbus is still the most common Typically cannot mix protocols unless over Ethernet © Extreme Telematics Corp. 2013 11/21/2018

Understanding Communications Protocol, Parity, Stop Bits, and Start Bits are all just definitions of what language is being spoken Baud Rate is the speed of the message Both the sender and receiver have to speak the same language at the same speed Many physical ways to get the message there. Wire, Fiber, Radio, Satellite are some examples The message is the same © Extreme Telematics Corp. 2013 11/21/2018

Communication Layers Several interchangeable pieces. All work together to communicate across devices Application Flow Calculator Plunger Lift Protocol DNP3 Modbus Physical Radio Frequency RS-485 © Extreme Telematics Corp. 2013 11/21/2018

Modbus Protocol Master/Slave Polled Architecture Broadcast (Everyone Hears Master) Limited by time to complete polling cycle Very easy to understand Supported by large number of devices Not the most efficient, but too much legacy to change overnight © Extreme Telematics Corp. 2013 11/21/2018

Postal System Same Layout Same Type of Device Sorting Center Mailbox Local Post Office Letters Data Register Local Slave Device Modbus Master Different Layout Different Type of Device © Extreme Telematics Corp. 2013 11/21/2018

Modbus Data Four Main types of Data Coils – True or False. Can be read or written and usually executes some action. i.e. Open or Close Valve Input Discretes – True or False. Read only. i.e. Battery Good Input Registers – 16 bit number. Read only. i.e. Battery voltage Holding Registers – 16 bit number. Read or write. i.e. Current Time Combine multiple 16 bit registers to create a 32 bit number. © Extreme Telematics Corp. 2013 11/21/2018

Modbus Format Station Address – The address that this command is destined for Command – Different codes to read or write different register types. Some codes indicate bulk data. Register – The starting register to read/write. Data – One to many bytes of data Checksum – Ensures the data integrity. © Extreme Telematics Corp. 2013 11/21/2018

Hazardous Locations Class I Div 1, Class 1 Div 2 Typical Different Gas Groups Different Temperature Codes IEC 60079-11 is the more up to date, international standard Referenced by latest CSA and UL standards Uses Zones instead of Divisions Div 1 Div 2 Previous Zone 0 Zone 1 Zone 2 IEC 60079-11 © Extreme Telematics Corp. 2013 11/21/2018

Hazardous Locations Zones Type of Rating Zone 0 – Gas is present Zone 1 – Gas sometimes present normally Zone 2 – Gas present under failure Type of Rating Explosion Proof – Explosion Contained Intrinsically Safe – Will not cause gas to be ignited. Lower component temperatures and low capacitance. Div 1 Div 2 Previous Zone 0 Zone 1 Zone 2 IEC 60079-11 © Extreme Telematics Corp. 2013 11/21/2018

Field Architectures There are a number of different ways to connect devices in the field. Typical Flow Monitor Independent Plunger Control Daisy Chain Shared Communication There is no right or wrong architecture. Each has its advantages and disadvantages © Extreme Telematics Corp. 2013 11/21/2018

Typical Flow Monitor Likely configuration of any existing network Other Logic implemented in flow computer Advantages Less Hardware Costs Simpler Hardware Configuration Disadvantages Limited space for programming Programming may be basic or non-existent Basic on site display if any Access needs to be given to service companies Costs to maintain software Expensive Sensors/Interfaces Solar Radio PLC/ RTU Battery Charger Zone 2 © Extreme Telematics Corp. 2013 11/21/2018

Independent Plunger Control Can Run standalone Add Radio Panel to connect to SCADA Advantages Local Interface Advanced Algorithms No Development Costs Service Companies Don’t Have Access to Flow Computer Cost Effective Sensors Disadvantages Additional Hardware Costs Solar Solar Plunger Controller Radio Barrier Battery Charger Zone 2 Zone 0/1 © Extreme Telematics Corp. 2013 11/21/2018

Daisy Chain Combine Independent Plunger Control with existing SCADA More Hardware Costs, but a lot of development and maintenance costs are offset Some Programming of PLC/RTU Required Solar Solar Plunger Controller Radio PLC/ RTU Barrier Battery Charger Zone 2 Zone 0/1 © Extreme Telematics Corp. 2013 11/21/2018

Shared Communication Shares radio instead of going through PLC/RTU Simpler Implementation, but uses extra Modbus address. Solar Solar Plunger Controller Radio PLC/ RTU Barrier Battery Charger Zone 2 Zone 0/1 © Extreme Telematics Corp. 2013 11/21/2018

Plunger SCADA Module Most Cost Effective and Flexible Eliminates the need for a barrier Uses Single Modbus Address Uses Cost Effective Sensors Eliminates battery, solar panel, and enclosure from plunger system Radio Battery Plunger Control Charger Solar Zone 2 PLC/ RTU Zone 0/1 Radio Battery Charger Solar Zone 2 PLC/ RTU Zone 0/1 © Extreme Telematics Corp. 2013 11/21/2018

Questions? © Extreme Telematics Corp. 2013 11/21/2018 23