PLC Memory
As I have mentioned previously, I have been working on a generic PLC course that I hope to release in some kind of online software format soon. I was able to test a prototype a few weeks ago with a …
Category: Software & Programming
Software and programming issues
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 …
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, …
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 …
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 …
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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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 …
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 …
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, …
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 …