Practical Tips and Techniques
PLC programs scan cyclically. This means that it is repeated many times and in the same order. The primary sequence of a PLC scan is reading the inputs, executing the program, diagnostics, and communication, and updating the outputs. We will look at these scan items with particular attention to how the ladder logic program is … Read more
Logic circuits in a PLC ladder logic program are either on or off. The inputs change, which will affect the outputs. This can be expressed in a timing diagram. The timing diagram or chart will show you how the ladder logic program will respond to the changing states of the inputs and outputs. This visual … Read more
We will now create a PLC with HMI Training and learning environment. We will use the Automation Direct Do-More programming software tied into the Advanced HMI learning package via Modbus TCP. All of the software is free and fully functional. Learn PLC programming and use a powerful HMI (Human Machine Interface) easily and freely. Setting … Read more
We are using Modbus TCP protocol, reading ten registers in the PLC, and displaying a bar graph in Excel. e will use Visual Basic for Applications (VBA) to communicate with a PLC. Previously we have used VB6 to communicate Modbus TCP. Sequence for Modbus TCP on Excel using VBA The following steps will be done: … Read more
We will use VBA in Excel to communicate to an Omron PLC. This will use the serial host link protocol. ACC Omron Host Link VBA In Part 1, we used VB6 to communicate from the computer to the PLC (Host Link Protocol). We will now use Visual Basic for Applications (VBA) to accomplish the same … Read more
Manufacturers have software to program the programmable logic controller (PLC) or the human-machine interface (HMI). However, there are a few free tools that will help in the development of your PLC programs. We will look at three software tools and show how beneficial they can be to you. Free PLC Software Tools Synergy – Share … Read more
