System integration: Model-based design tools write control software for industrial equipment
A partnership between Rockwell Automation and The MathWorks helps PLC-based machine builders benefit from simulation software, reducing design time 50%.
Machine builders have a new design software tool that can write the related automation software, saving 50% in design time. Approached by a wind turbine manufacturer about a year ago, engineers at Rockwell Automation were asked, "Can you get ControlLogix to run
C code?" Separately-and successfully-Matlab and Simulink software from The MathWorks Inc. was generating C, C++, VHDL and Verilog code from models, which would be run on PC-based control systems. Such model-based design reduces programming errors and speeds development time by allowing code to be quickly tested and changed.
Following a few months of integration and negotiation, The MathWorks developed a tool to transform its model-based designs into code for programmable logic controllers (PLCs) called Simulink PLC Coder .
Tom Erkkinen, Simulink PLC Coder product manager for The MathWorks, and Jason Weber, strategic alliance manager for Rockwell Automation, sat down with Control Engineering to talk about the partnership, and the product's advantages for machine builders, system integrators, and end-users of PLCs.
The partnership made a lot of sense from both perspectives. "Matlab owns the wind turbine space," said Weber, "but their software only ran on PC-based hardware." Erkkinen said, "We learned that if The MathWorks wants to support industrial automation as a whole, we have to support PLCs. I cannot go to industrial customers and not do this."
The MathWorks software is used to design, simulate, test and validate complex mechatronic systems built on PC-based controls. Development involves creating models that capture electrical, mechanical, controls and process parameters in a block diagrams and algorithms that show the interrelationships. As the models are run, the software creates plots and captures data that generates code for algorithms, and also generates code for test cases. This lets machine builders test and validate system design before generating executable code for a specific hardware platform, such as microcontrol units (MCUs) and field programmable gate arrays (FPGAs).
The MathWorks doesn't handle the executable code portion of the process. "We don't produce compilers," said Erkkinen. "so we needed Rockwell to get us to the hardware. PLCs are a unique animal, but given our software architecture, it was fairly easy to leverage our coder for a new language. That means it's not a version 1 coder. Its roots go back to 1992."
The hardware, in this case, is ControlLogix PACs using RSLogix 5000 software. Simulink PLC Coder takes the Matlab or Simulink algorithms and generates IEC 61131 structured text (ST). RSLogix 5000 takes ST and produces an executable for the PLC. "It also produces‘hooks' that link back to the algorithms, which show that the model matches the executable code generated, as well as [produces] code for test cases," said Weber. "Once in RSLogix, I can compare test case results. Now I know that what I implemented matches my model."
Such model-based design has many benefits:
•kkinen and Weber.
•ior, according to an Aberdeen study, "System Design: New Product Development for Mechatronics," cited by Erkkinen.
Weber added, "Simulink PLC Coder software from The MathWorks makes Rockwell Automation products more valuable. By bi-directionally synchronizing software tools, our customers will be able to make changes very quickly and improve communications among those involved."
Also see from Control Engineering :
- The MathWorks releases version 2010a of Matlab, Simulink products
- Mark T. Hoske, editor in chief, and Renee Robbins, senior editor, Control Engineering
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