Understanding OPC: Basic Overview Colin Winchester VP Operations Nathan Pocock Chief Architect & Developer Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission Understanding OPC: Basic Overview Agenda – 60 Minutes Original problem – How to share data Original solutions OPC Solution Open and Industrial Client/Server Architecture - COM PC to PC connections – DCOM What can you do with OPC Now Answers to some common questions Future Direction Questions & Answers Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission Original Problem: How to share data? 1) How to share data from 2) How to share data equipment like PLC’s? between programs and PC’s? Software Software Application Application Software Software Application Application Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission Connectivity means…. Enterprise Application Accessing plant-floor data User Interface displaying plant-floor data Transport Layer Ethernet, RS232, RS485, Radio etc. PLC / Device Allen-Bradley, Siemens, GE, Modbus, Automation Direct etc. Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission Original Solution 1) How to share data from equipment like PLC’s? InconsistentInconsistent implementations,implementations, i.e. i.e. features supported and Vendor A HMI / SCADA Vendor BfeaturesHMI / SCADA supported and reliabilityreliability Modbus DF1 Other Modbus DF1 Other Driver Driver Driver Driver Driver Driver EachEach vendor vendor has has implementedimplemented their their ownown Protocol Protocol driver.driver. Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission Original Problem 2) How to share data between programs and PC’s? Data inaccessible to Enterprise other systems System Self-customization limitations, or inability Expensive customizations often HMI/SCADA Other Application Application required Data sharing via Modbus / DF1 etc. Unsupported *.CSV import/export Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission First Solution, DDE Protocol drivers were no longer within HMI DDE Server contains HMI / SCADA protocol definition Application HMI connected using DDE Topics HMI tells DDE Server “read DDEDDE Server Server this”, “write that” (Protocol Converter) (Protocol Converter) DDE Server responsible for all I/O Different HMIs can connect PLC to a DDE Server Some Data sharing possible Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission DDE, Scalable Solution? Different systems can connect to a DDE Server Accessible over the Network using NetDDE Add more DDE Servers More device support Load distribution Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission DDE, Good Solution? Performance issues Decoupled HMI from NetDDE reliability Protocol drivers No Standards on tag DDE Server market database emerged No Browsing! More “driver” choice No quality information HMI vendors could focus on their core No Client control of Poll product rates Accessible to Any DDE No timestamp Application No security Not easy for network configuration and usage Limited number of client/topic connections Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission A Standard Was Needed! Software to Software interface (Problem 2) Keep Client/Server model used with DDE Better performance needed Security needed Needed to support more sophisticated data types (variants and structures etc.) Needed to be more scalable Internet capable A more “future-proof” framework was needed Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission OPC, the new Standard OPEN Standards based The OPC Foundation controls the standards Automation Industry Organization Not controlled by any one company – managed by board of directors elected by the membership Volunteer effort Created 1996 – by 6 founding members Companies from all over the globe Software Toolbox - a charter member, joining in the foundation’s first year Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission OPC, the Promise Industrial Automation Focus Timestamp support Quality flags – Ensuring Data Integrity Interoperability: Testing & Certification Client/Server architecture Scalable solution Flexible means of data access Easy for end-users Security using Microsoft standards Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission OPC Solution, Similar to DDE, but better Same client/server HMI / SCADA architecture Application OPC Server contains protocol definition Tag Database clearly defined OPCOPC Server Server (Protocol Converter) HMI makes OPC calls to tell (Protocol Converter) the Server saying “read this”, “write that” and how often PLC/other Equipment Performance gains Quality and timestamp information now accessible Easy configuration for the end-user. Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission OPC Solution HMI/SCADA OPC Clients • Standard software to software interface • One connection: OPC • Communications infrastructure decoupled from the HMI/SCADA • Microsoft Security OPC OPC OPC Server A Server B Server C • Improves performance •Flexibility • Choices Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission What’s in a Tag/Item? OPC Server exposes OPC Client PLC memory addresses as “Tags” Dev1.Tag1 Dev2.Tag1 Tags are a friendly 4001 obj1.prop.val Dev1.Tag2 Dev2.Tag2 name, that maps to a 4001 obj2.prop.val memory register in the PLC. OPC Server Decouples the OPC Client from the Modbus / DF1 etc. BACNet, Profibus etc. underlying Device Protocol and Memory Register knowledge. PLC specific PLC specific addresses addresses Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission OPC – Data Access Capabilities Browse computer for available OPC Servers Browse the server for available Tags Read 1..x Tags in a single call Write 1..x Tags in a single call Subscribe to Tags and receive updates when their value(s) change. Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission OPC DA, Data Acquisition Read these 1…x ReadReadRead these these these 1…x 1…x 1…x Tag(s) one time, Tag(s)Tag(s)Tag(s) one one one time, time, time, Synchronous I/O TELL ME when andandTELL I Iwill will ME wait wait when for for Blocking call you have results youthethe response haveresponse results Good for round-robin OPC polling-type Client applications Asynchronous I/O Faster method, compared to OPC Synchronous Server Development requires different way of thinking Different Locations Cache Device Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission OPC DA, Data Acquisition Subscriptions offer best optimization TheseThese tags tags have have changedchanged values…. values…. OPC OPC client Client requests a subscription OPC Server does OPC the polling Server OPC Server sends change notifications to the client Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission OPC Quality Codes Specifies if the Tag value is something you can trust or not. 16-bit Bitmask of values (low 8 bits): 0 = Bad (00000000) 64 = Uncertain (01000000) 128 = Reserved (10000000) 192 = Good (1100000) High word is reserved for Vendor use. Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission OPC, How does it Work? OPC Server •Any OPC Client OPC Group •HMI/SCADA OPC OPC Item •Custom Application OPC Group OPC Item OPC Item OPC Client connects to an OPC OPC Item OPC Item Server. Client adds a “Group”. Client adds “Tags” to Group. Hardware specific networks and The poll-rate is set in the Group. protocols You can add multiple Groups. Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission Client/Server and OPC DA Ethernet/IP The Client Consumes data Ethernet Human services Machine Defined as the OPC Interface The Server Provides Client data services OPC DA Modbus RTU Client Side COM is the Middle Man Microsoft COM OPC Servers and OPC DA Defined as Clients in most cases Server Side the OPC are separate Server programs now Communications OPC Servers only Drivers act on commands from an OPC Client Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission OPC, Dependent upon COM An OPC Client connects to an OPC Server through COM An OPC Client connecting to an OPC Server on a different machine connects through DCOM and must be authenticated. I Iwant wantTell meto to your connectconnectlogin to nameto you you and MyMyLet user user me name checkname my password! isisAccess “fred” “fred” andControl and PC – 1 OPC Client passwordpasswordYes,List…. you is areis on PC – 1 OPC Client my“*****”“*****” list… I will OPC Client COM run-time grant you access!OPC Client COM run-time Security Security Provider Provider Content is Copyright Software Toolbox, 2008 No re-use or copying without written permission OPC DA, Scalable Architecture A server can OPC Server support multiple OPC Client OPC Client OPC Client/ Clients, Visualization & Database Logging OPC Server Alarming etc. concurrently OPC Server Many servers can exist on