PLC Philosophy
Wednesday afternoon I did a webinar for Control Engineering magazine. Usually they have two or three people talk on a topic, but for some reason I was the only person available, so I had to do the whole thing. I …
Tag: programming
Ladder Logic 306a: Simulation
Today’s post relates to a new method I am using to teach some of my advanced classes. In a basic PLC training class, pushbuttons and pilot lights built into a trainer are used to complete exercises, usually in order to …
MRO – Moving HMI Designs
Today’s post is a guest post on HMI programming from MRO Electric, an automation product supplier. Designing HMIs for Mobile Devices Well-designed human-machine interfaces (HMI) reduce operator error, saving companies millions of dollars by reducing down-time and increasing worker safety. …
Ladder Logic 403: Message Scrolling and Multiple Faults
Today’s post is in answer to a question from Bruno on my last post on Faults and Messages. Bruno asks “If two faults happen at the same time, will this procedure work?” This is a more complex question than it …
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Ladder Logic 209: Faults and Messages
This post is another in my series on Ladder Logic. As with the other posts in this series, I am using generic logic and addressing so that it can apply to various PLCs. In previous posts in this series I …
Advanced PLC Training using Industrial Equipment
I just got back from teaching a class in California using the conveyor and training demo mentioned in my previous post on Automation NTH. I have discussed training quite a bit on this blog before, but I feel like this …
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Ladder Logic 208: System Routine 2
Today’s post is a continuation of the series on PLC Ladder Logic I started several years ago; for more of these post click on the PLC tab at the top of the site. In particular this continues my discussion of …
Ladder Logic 305: ASCII and Strings
Today’s post covers ASCII, string manipulation and how to deal with readable text in a PLC. The picture above is from a ControlLogix program (Allen-Bradley, RSLogix5000 v.16) I wrote back in 2006. The program communicated with a PC-based Cognex machine …
Tag Structures and Dotfields
Today’s post is in response to an e-mail I received asking for my thoughts on Tag Structure. In part, George Steel wrote: Great site, thanks for all your efforts. I am working on positioning my org to move from RS500 …
Ladder Logic 106: One Shots
A one shot, or “differential”, is used to develop a signal that is exactly one scan in duration. As shown in the diagram above, when a signal is applied to a contact (a Pushbutton in the diagram above), no matter …