I was cleaning up over the holidays and came across a couple articles that I had saved from earlier in 2009. I’m sure you’ll find them interesting. Both articles describe how people are taking PC based automation to the next level to reduce cost and integration time.
The first article, PC–Based Controls Help Freeze Escalating Energy Costs, from ControlGlobal.com (May 13, 2009) explains how a company used PC’s to standardize control in multiple plants. Not only were they able to standardize, but the power of the PC allowed them to drive cost out of the process by using highly advanced control algorithms. Implementing the algorithms with PLC’s might have been possible, but the solution “would have been unwieldy and impractical”. Using the PC allowed them to model the process in real time to design the most efficient algorithm. In addition to better algorithms, PC control made is very simple to communicate with the rest of the plant and even between plants.
The second article, USB Flexes Its Industrial Strength from Electronic Design (May 23, 2009), describes the multiple advantages of USB in PC based automation. It explains that although the overall speed of USB 2.0 is slower than that of Gigabit Ethernet, USB continues to be a great choice because of it modularity and the lack of need for Gigabit speeds. An important point that the article misses is that USB can be implemented in such a way as to have a guaranteed maximum latency (as is done in the Expert I/O 1000), whereas Ethernet depends on the number of devices attached to the node. The article goes on to explain that USB speed is soon to surpass Gigabit Ethernet. The new USB 3.0 specification increases the bandwidth to 5 Gigabits/second.
Make no mistake, PC based automation is alive and well and continues make gains into process and control applications where PLC’s once easily dominated.

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