OPC Overview 

OPC is an industry standard interface that defines a client / server structure useful for industrial control applications.  Servers are executable (.exe) files that run in as a separate process on a PC. They continuously scan the I/O device registers (usually a PLC) and place the data into a local table in the PC. The registers are user defined as tagnames mapped to physical device locations. (e.g. TagProx1 =   B3:0).

The client controls run under the user application which is usually a Visual Basic app. The client subscribes to the server defined tags.The server updates the clients as data changes. The client would then keep the data in its own table. A server can have many clients. Consolitech offers clients as specific functions and one as a general client control that can be used to present tag data to the user app.

Some of the client controls are:

• OPC client I/O Controls - OPC I/O control tools for States (input value sets control state-text,color,picture,etc.; Output Push Buttons; Read/write Textbox- displays PLC value, edit and write to PLC; Output Slider-sends scaled value to PLC; Input Bargraph; Input Gauge; Output OptionButton-writes selected option; Output CheckBox - writes ON or OFF
  
• OPC general client - user app can read/write server tags through this control

• Alarming - active and historical alarming display as a list of user supplied messages. Triggered on preset I/O values.
• Data Logging - log I/O data and view in time selectable window, stored in MS Access database
• Real Time data Trending - real time graphs (200-800 throughput/sec)
• Part Database (recipe) - link MS Access database to PLC
• SPC - Statistical Process Control X Bar and R charts
               

Link to OPC Foundation website for more details on OPC

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