Blog Archives

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

PLC Platform Sample Request – CLGX Example

In a post back in March, “Request for PLC Information and Samples“, I received quite a few responses offering PLC information on various platforms. Unfortunately after sending e-mails to quite a few of the respondents I haven’t received any info,

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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 Scanning Solution

Last week I posted a fairly straightforward question at the end of my post on PLC Scanning. I then shared the post on Linked In as well as on my company’s Facebook page. One reason I share these posts on

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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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Ladder Logic 304: Timer Application

Today’s post is in response to Dave Tompkins, who posted a request for help last week for an application. Since he posted it on one of my series posts on ladder logic (204: Auto Sequences) I decided to frame it

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Posted in Applications, PLCs, Software & Programming

Ladder Logic 303: PLC Forensics

Today’s topic involves a project I have been working on over the last few months. The project consists of adding process equipment including tanks, pumps, valves and instrumentation to an existing system… while it is running. Because production runs 24

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Posted in Integration, PLCs, Software & Programming
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