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industrial control system...
Introducing Bedrock OSA® Remote
- Intrinsically-secure PLC and RTU control
- 10 or 20 channels of universal I/O
- Free IEC 61131-3 engineering software
- -40ºC to +80ºC temperature range
- Rugged, all-metal case 5.4 in x 8.9 in x 2.3 in
Who needs IEC 61131?
October 30, 2019
In May of 2018, Control Design printed an interesting reader comment trail discussing the benefits of open computing. It consisted of responses to a reader who was planning to supplement his expertise in PLC-based ladder logic with object-based skills around the IEC 61131-3 standards and asked if function block reusability was the biggest benefit of object-oriented programming (OOP). Most respondents agreed that function block reusability was indeed significant because it allows users to easily encapsulate work from one project for reuse in the future. But they cited numerous other benefits that are well-worth sharing. Here are some of those capabilities:
- Support of multiple programming languages, including ladder logic, structured text, and sequential function charts. Function blocks provide a powerful way to integrate multiple languages. A communications function block, for example, can be developed in structured text and then reused easily within a ladder logic program.
- Portability among manufacturers. Because all manufacturers use the same standard set of function blocks and code construction methods, it is easier to port code from one to another.
- The ability to use the right language for the right job. In IEC 631131-3, for example, it is possible to turn off 16 digital outputs all at once. Doing so in ladder logic requires creating each coil separately, attaching each on one side to the logic and the other to the power rail. In structured text, however, you can pull each output into a user-defined array, reducing it to three lines of code.
- Greater ability to protect structured text from human error. With IEC 61131, you can encase code into a function block created by a senior programmer and insert that it into the ladder logic. You can then lock the function block to prevent field technicians who may not have object-oriented experience, from modifying it.
- Software maintainability and robustness. Object-oriented programming allows users to make changes to working control systems without negatively affecting the overall system behavior.
The respondents also commented on the ease of transitioning from ladder logic to OOP. Generally, they felt that anyone skilled in ladder logic can learn OOP easily, but it does require a commitment to thinking about programming in a different way. As one person put it:
“As automation professionals, we are used to thinking in a procedural way: Start at the top, go to the bottom, start over. With OOP, we start thinking about objects and how they interact with each other rather than thinking in terms of a procedure. We as engineers have trained ourselves to think procedurally and in a linear fashion; to remain competitive, this thinking must be changed to think of function blocks of isolated objects that interact with other objects.”
At Bedrock Automation, we know that making this transition can have a tremendous payback in terms of reducing the cost of application development and maintenance as well as leveraging the benefits of improved digital connectivity for overall operations. That is why we have invested so heavily in ensuring that this can be done without risk of cyber intrusion.
Read the whole Control Design feature here.
To read about the latest upgrades to Bedrock IEC61131-3 compatible engineering software and download your free copy – go here.
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