Why use OPCcalc?

OPCcalc allows you to read and write data to one or more OPC Servers with minimal effort. You simply enter the logic in a VB.Net-like syntax using the OPC tag names directly in your equations.

Click below to see a sample OPCcalc equation library

Normally, you would use a programming language (such as C, C++, C#, or Visual Basic) and underlying OPC calls to develop such equations. Using OPCcalc, you only need to provide minimal information for the equation including:

  • Name of the OPC tag to receive the result of the equation
  • Name of OPC tags, variables, functions, and constants used in the equation
  • Associations to be made between the OPC tags, variables functions, and constants

The above information is stored in one or more text files called OPCcalc libraries. Once you have provided this information in a library, OPCcalc builds a compiled Visual Basic .NET executable that will perform the calculations and output the results to OPC tags on the OPC Server.

OPCcalc will dramatically cut your development time and easily allows non-programmers to create complex calculations that read and write OPC data.

Standardizing: OPCcalc gives you a standard method for

  • Connecting to one or more OPC servers
  • Accessing current (DA) and historical (HDA) values and aggregates
  • Handling lost connections
  • Retrieving tag values
  • Writing tag values
  • Providing application error handing
  • Scheduling execution
  • Performing aggregate function calls (average, min, max, …)
  • Code documentation

Advantages: Using OPCcalc offers many advantages:

  • Can significantly reduce the number of lines of code
  • Accepts OPC tag names directly in logic
  • Automatically handles equation run-intervals (down to 50 milliseconds)
  • Generates uniform and easy to maintain program
  • Multiple debug options including built-in snapshots of running equation inputs and outputs
  • Built-in functions for current, historical and aggregate OPC tag values
  • Support for user-defined functions and subroutines
  • Local variables that retain their values between executions (allows you to reference values from previous runs)
  • Order-of-execution control for all equations in a library
  • Equation results can be tested over multiple executions before equations are deployed
  • Ability to recalculate equations if logic or inputs have changed (requires OPC HDA)
  • Built-in calculation diagnostics (latest completed execution and execution times)
  • Remote monitoring, starting, and stopping of calculations (packaged Scheduler or custom code using our API)
  • Access to the entire VB.Net language (math function, language structure,..).

Because you can easily move data into and out of one or more OPC Servers, OPCcalc can be used to quickly create interfaces to/from/between OPC Servers and other data sources (relational databases, etc). 

OPCcalc and Visual Basic.Net

Exele’s calculation products do not require Visual Studio/Visual Basic.Net to build calculations, although certain functions may require it (i.e. creating user functions, Visual Studio debugging). If you require Visual Studio, we support most versions including the free “Express” versions available from Microsoft.

Because OPCcalc creates .Net calculation processes, you can take advantage of this rich framework within your equation logic.
This includes

  • Access to the entire Visual Basic language and .Net Framework
  • Support for user-defined functions and subroutines
  • Ability to call external assemblies and Web Services
  • Use of Visual Basic constructs (If..Then..Else, Arrays, Variables)
  • Retrieval of values from relational databases (Oracle, SQL Server, Access, …)
  • Outputting of data to relational databases
  • Reading and writing of files