Blog Archives

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

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Posted in PLCs, Software & Programming, The Book

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

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Posted in Controls Design, Documentation, Software & Programming

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

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Posted in PLCs, Software & Programming

Why BCD?

Computers hate decimal. I mean, just because we have ten fingers and ten toes, we think we can dictate what base other computing entities should think in. Well, it’s really quite inefficient when you think about it, its so easy

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Posted in Software & Programming, Training

Request for PLC Information and Samples

I mentioned last week that I am working on what I believe is the first truly advanced non-platform-specific book on PLC Programming. My friend Tony over on Factory Automation Software Blog has reviewed some books that come the closest, but

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Posted in PLCs, Software & Programming, The Book

Ladder Logic 402: Data Manipulation and Filtering

In last weeks’ post, I discussed acquiring data using a PLC to capture values from an analog card. I showed some fairly straightforward methods of capturing data using FIFO methods, averaging data values, and how some of the ladder logic

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Posted in PLCs, Software & Programming

Ladder Logic 401: Data Acquisition and Analysis

Todays post is in response to a request by Quy Phan, who I met a couple of weeks ago while teaching for Automation Training in San Diego. He is having some problems with some existing equipment concerning noise on his

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Posted in PLCs, Software & Programming

Ladder Logic 105: PLC Scanning

In my last post on PLC Memory Organization, I mentioned that I had not really covered how scanning actually works in a programmable controller. This is certainly a topic that needs to be discussed for an understanding of PLC programming,

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Ladder Logic 104: Memory Organization

One of the first decisions that needs to be made when designing a PLC system is memory allocation and organization. In the early years of the PLC memory came at a premium… 1K (one kilobyte) of memory for the program

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Advanced PLC and Industrial Training

I would like to make myself available to any company or group, worldwide, that desires truly advanced training in industrial automation-related fields.

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Posted in Software & Programming, Training
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