IAS Blog

Visual Basic - Real Basic "Structured Text"

Posted on 04/01/2010 at 10:45 am by IAS
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We have a customer that has an application coming up that will require the Modbus protocol to speak with some VFD's(Variable Frequency Drive). Most of our PLC offerings already support Modbus with little or no programming required however this one particular processor does not. So I am helping this customer write the Modbus protocol in the PLC.

Most people have heard of Visual Basic. Its Microsoft's basic programming software. I have already used Visual Basic to write the modbus protocol to speak with some of our industrial automation products. Recently I have been using another programming software called Real Basic. Real Basic's strength is that it can compile to run on Windows, Mac, or Linux. I found moving my VB code to Real Basic was very easy. Just cut and paste and slight changes to the syntax did the trick. It worked.

VB Modbus Code

Real Basic Modbus Code

Structured Text Modbus Code

Now to cut and paste code from one PC software development environment to another is one thing. But from PC development to PLC development software thats another thing. I guess its a sign of the times. PLC's have come a long way. The good news with PLC's is that they still support the simpler ladder diagram but they have some advanced capabilities as well.

In fact many PLC's now support programming in Instruction List (good luck!), Ladder Diagram, Function Block, Structured Text, and Sequential Flow Chart. A language for any need.