Programmable logic controllers (PLC) use a cyclic scan. The time that it takes to complete one scan is called Scan Time. Typical scan times range from 10 milliseconds to 10 microseconds. This translates from 0.01 to 0.0001 seconds per PLC scan. Understanding how the program scan will help us in programming and troubleshooting the PLC.
The simplest scan cycle of a PLC consists of 4 steps. Read inputs, execute program, diagnostics, and communication, and update outputs.
We will be looking at each of these steps in a little more detail as we discuss the PLC program cyclic scan. Let’s get started. Keep on Reading!
The productivity suite software now contains a plc simulator. The software is a free download and is available from automation direct. This software will now allow you to test or troubleshoot your program without the physical hardware present. The entire family of controllers can use the simulator. P1000, P2000, and P3000 emulation can happen on the following parts of the productivity series hardware:
– P1000 CPU’s and local I/O stack, P2000 and P3000 CPU’s and local bases
– All basic I/O modules, both analog and digital
– Modbus TCP Server/Client connections on external Ethernet port
The simulation mode is available on the Productivity Suite version 3.8.x.x or higher. We will be discussing the PAC (Programmable Automation Controller) PLC Simulator. Testing this simulator will be done using our first program (Start-Stop Circuit) and the PID instruction in our Productivity 1000 series. We will also be connecting to physical hardware after using our simulator to test the program. Let’s get started. Keep on Reading!
Accelerate Learning …
It is a good time to be in the automation business. Technologies are merging and communicating like never before. What was impossible is now possible for the industrial plant floor. We are looking forward to the New Year and new possibilities for implementing your control solution.
Each year we like to take a few minutes and reflect on the past, current, and future of ACC Automation. You have helped us to build the site that you see today through questions, comments, and suggestions. Thank you.
2019 has been our best year yet thanks to you. Keep on Reading!
We would like to take a few minutes and reflect on the past, current and future of ACC Automation. Your questions, comments and suggestions have helped us to build the site that you see today. Thank you.
YouTube Channel : ACC Automation
2018 has been our best year yet thanks to you. Keep on Reading!
Last time we created our first program and transferred this to our connected Productivity 1000 Series PLC. This was programmed with our computer running the Productivity Suite Software. One of the most important aspects of programming the PLC is to document. This will aid you and your team in programming, troubleshooting, and modifying the automation control system. Your documentation should read like a book so information can be quickly obtained when required. Time spent on the documentation will be priceless when you go to read your program in 1, 3 or 10 years from now. The Productivity Suite software provides several different methods for documenting your program.
Tag Names and Details, Task Names and Descriptions, Rung Comments and Instruction comments are the ways that we will be looking at documenting our program.
Let’s get started. Continue Reading!