ACC Automation: PLC & Industrial Control Learning
Practical Tips and Techniques
Programming a PLC can sometimes be a daunting task. The best method is to break the task into smaller steps. These are the steps that I have used for years to develop PLC programs. We will apply them to a die-stamping application. Step 1 – Define the task: What has to happen? This is written … Read more
Process control can be a bit intimidating. We will try and break down both On/Off and PID control in a fun way. This is a simple analogy without any math. On-Off Control Explained On/Off control can be used effectively with temperature control. Everyone’s house usually has a temperature controller that uses an On/Off control. The … Read more
A one-shot in the PLC will turn an output on for one scan. This is used to trigger events that should only happen once. An example of this would be to increment a value in memory. If a one-shot is not used, then every scan of the PLC will increment the value. What is a … Read more
This post is a further follow-up from my original ‘Here’s a Quick Way to Understand PLC Inputs and Outputs.’ There are two different kinds of PLC outputs, Discrete and analog. Discrete outputs are either ‘ON’ or ‘OFF’; 1 or 0. You can think of them as a single light bulb. Analog outputs have a range … Read more
This post is a further follow-up from my original ‘Here’s a Quick Way to Understand PLC Inputs and Outputs.’ There are two different kinds of PLC inputs, Discrete and analog. Discrete inputs are either ‘ON’ or ‘OFF’; 1 or 0. You can think of them as a single switch. Analog inputs have a range to … Read more
I have been writing PLC programs for over 20 years. I often get asked what the best way to learn PLC programming is. Programming in the way I was taught in college was with the Motorola 6809. (Yes, I know that I am dating myself) This was microprocessor programming, but it was the best way … Read more
The hostlink communication protocol is a method developed by Omron for communication to PLCs and other equipment. This ASCII-based protocol is used over RS232 or RS422/RS485. It is a many-to-one implementation, meaning you can communicate with up to 32 devices back to a master. (1: N) This communication on the industrial floor can control PLCs, Temperature … Read more
We will now look at the secret of using timers in the PLC. Timers are used in the majority of PLC programs. There are also a wide variety of off-the-shelf industrial timers that you can use. The implementation of timers can be vast; however, it all starts with a TIMING CHART. Timing Chart – Secret … Read more
Looking at a stop-start jog circuit in the PLC will help us understand the differences in hard-wiring the circuit and programming. Basic Start Stop Circuit Let’s start with the primary start-stop circuit. Here is what it looks like hard-wired. (Physical switches wired to outputs devices, such as motor contactors and relays.) When the start pushbutton … Read more