Welcome to the second part of my ladder logic tutorial. In part 1 of the ladder logic tutorial I introduced you to the very basics of ladder logic and to some basic instructions.
In this second part of the tutorial I will teach you how to solve actual problems with ladder logic and how to use it to build PLC programs. At the same time you will be introduced to several other ladder logic instructions:Set / Reset CoilsSet or Reset PrioritySet / Reset Function BlocksSR Function BlockRS Function BlockBuilding Logic with Ladder LogicLogic Gates with PLC InstructionsOR and AND GatesNOT Logic GateInterlocking with Ladder LogicLadder Logic Exercise 1: InterlockingOne [...]
A PLC counter is a function block that counts up or down until it reaches a limit. When the limit is reached the output is set.
The thing is that counting is in fact widely used in PLC programming. Often you will have the need to counts different things. An example of this could be to keep track of how many times a process has been completed. Or how many products has been produced.
Some of the most essential functions in PLC programming are the timers. Time in PLC programs is used almost everywhere from delaying the start of a motor to prolonging a signal. PLC timers are used exactly for that. Although they at first can seem confusing it doesn’t take a lot to understand how they work and how to use them.
When it comes to automation and manufacturing ISA-88 or just S88 is inevitable.
It is a standard for published by The International Society of Automation (ISA) that sets out models and terminology addressing batch control. The standard was published in an attempt to standardize and thereby making it easier for automation suppliers to integrate, communicate and configure batches. It is adopted by Europe as IEC 61512-1.
Today, the standard is used by most manufacturers and automation suppliers that deal with batch control. Especially productions of food and medicine utilizes if not the whole, then at least parts of the standard to keep track of their batch production.
Do you know how to scale your analog input? Or wire your analog output?
Many people struggle with analog signals in PLC programming. The wiring and how to use an analog input or output in your PLC program can be tricky. Most often you will see digital example PLC programs and in my Structured Text Tutorial most of the examples are digital programs.
I’m writing this article because many of you wanted to learn how to use analog signals in PLC programming. Analog signals are used widely in PLC programs but also often used in a SCADA system. So how do you connect that 4-20mA analog transmitter to your PLC and use it in your PLC program? How do you scale an analog [...]
One of the official and widely used PLC programming languages is Function Block Diagram (FBD). It is a simple and graphical way to program any functions together in a PLC program. Function Block Diagram is easy to learn and provides a lot of possibilities.