Can One Controller Do It All? - 1. Logic ControlWritten by Bob Nelson Wednesday, 23 September 2009 00:00
Table of contents
Performance and processing speed: In machine, factory or process control, controller performance is a key element in productivity gains. As you strive to improve the electro-mechanical performance of your application to yield higher throughputs, the performance of your automation system must keep pace. The execution time, high-speed interrupt handling and “segmentable” scan times of your controller all contribute to application performance.
Scalability: Ideally, you would have one engineering environment to configure all of your applications, which, in turn can be downloaded to the target platform meeting your requirements. This separation of program and platform allows you to focus on solving the application problem, followed by selecting the best, most cost-effective platform for your specific application.
Configurable system-wide diagnostics: You can always program diagnostics into your code, but this takes time, and often is sacrificed to meet project schedules. A controller with built-in diagnostics that can be easily enabled or configured ensures that this important aspect of your solution won’t be skipped.
Availability of multiple programming languages: Relay Ladder Logic is expected in a logic controller, but aspects of your application may be better implemented using graphical function blocks or a high-level programming language. The IEC 61131-3 standard for PLC programming languages defines five languages that range from ultra-efficient “machine code” to the graphical representation of sequences.
Potential for reusable code: For industrial automation, leveraging a library (from the supplier or defined by you) of common program elements and using these elements repeatedly reduces implementation time and improves program consistency.
Investment security: Rather than demanding new products, many users push for longer life cycles for their existing products and architectures while taking advantage of advances in technology. The result is having the “latest and greatest” without the need to “rip and replace.”