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Articles Do-More Inputs Outputs PLC PLC Basics PLC Learning Scan

Ladder Logic (NO) Contact – 3 Things to Know

Normally open (NO) contacts or inputs in the PLC ladder logic program do not mean the same as a wired normally open switch. NO contacts on the ladder logic provide the logic condition for the rung to turn on the output.
Ladder Logic Normally Open (NO) Contact - 3 Things to KnowWe will be looking at three things about the normally open (NO) contact on our ladder logic program. The normally closed NC ladder logic contact will also be discussed at the end. Let’s get started.

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Articles Communication Ethernet IP Client Ethernet IP Server HMI Modbus RTU Modbus TCP MQTT PLC PLC Basics PLC Learning

Don’t Get Caught Without These 3 PLC Requirements

If you are looking to purchase a PLC system, there are three key components that you should look for. If your current system does not contain these features, you need to replace it with one that does as soon as possible. The three most important features you should look for in your new PLC system are the open communications protocol, the ability to integrate easily with other methods, and the ability to have remote access. Without these three essential requirements, your PLC system will be far less effective and will be more expensive to operate than it needs to be.
Don't Get Caught Without These 3 PLC RequirementsWe are all data companies that need the information for continued improvement. The industrial internet of things (IIoT) is essential, and the ability to take advantage of this starts with the hardware you specify for your PLC control. PLCs are now considered edge devices. This means that information should be able to be sent and received to the PLC controller when it is required.

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Articles HMI PLC PLC Basics PLC Learning

PLC Learning Series – Understanding Numbers

All programmable logic controllers (PLC) have the same numbering system at their core. This is the same with all computers as well. The status of any memory location can be either on or off. A one (1) will represent an on or “True” status and zero (0) will represent an off or “False” status. This is called binary.

Understanding PLC Numbering Systems
We will be looking at how numbering systems work and some of the common systems that programmable logic controllers use. Let’s get started.

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Communication Database HMI HostLink Omron CP1H PLC PLC Learning

Omron PLC Node-RED Serial Communication


PLC manufactures have their own proprietary protocols. These methods of communication will allow you to program the controller. Other protocols will allow you to collect and log information from the programmable logic controller. Node-RED has the ability to read and write to the Omron controller using special protocol commands.
Omron PLC Node-RED Serial Communication
We will connect Node-RED to the Omron CP1H PLC. A serial RS485 interface will be used for communication to the industrial controller. We will demonstrate reading and writing using Host Link (C-mode commands) to the Omron PLC. Let’s get started.