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 …

Ladder Logic 305: ASCII and Strings Read more »

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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 …

Request for PLC Information and Samples Read more »

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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 105: PLC Scanning Read more »

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When designing a control system, sometimes it becomes necessary or advantageous to communicate with devices that were not made by the PLC manufacturer. If these devices need to be placed on an Ethernet, DeviceNet or Profibus network there are methods …

Non-Native Devices: .eds and .gsd files Read more »

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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 …

Ladder Logic 303: PLC Forensics Read more »

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