Category Archives: PLC Basics

PLC Fiddle – Online Editor and Simulator in your Browser

I have recently come across a free virtual plc simulator called PLC Fiddle. It will enable you to create simple PLC ladder logic code within your browser. This is an ideal way in understanding PLC concepts for industrial automation. All of the basic PLC instructions that come with most plc units have been incorporated in this virtual PLC software.
PLC Fiddle is currently in an early stage of development but is functional enough to be helpful to you in learning and understanding PLC concepts. We will be reviewing this software and creating a few common basic circuits. Using the simulator we will test our circuits and monitor our PLC programs (circuits). Let’s get started. Continue Reading!

BRX PLC Math Instructions

Math instructions are used to perform mathematical calculations. The BRX PLC has math instructions that can be used in a wide variety of applications. We will be looking at the INC increment, DEC decrement, LERP linear Interpolation, RANDSEED Random Number Seed and the MATH Calculated Expression instructions. Your automation system that you implement may involve some or all of these instructions. As a system integrator you will require the use of these instructions in your commissioned programs.
Let’s get started with the BRX PLC Math Instructions. Continue Reading!

BRX PLC Compare Instructions

Compare instruction are often used in PLC programs to test pairs of values. The output of this comparison conditions the logical continuity of a rung. The BRX series of programmable logic controllers has the following compare contact instructions.
= (if Equal contact)
<> (if Not Equal contact)
> (if Greater Than contact)
>= (if Greater Than or Equal contact)
< (if Less Than contact)
<= (if Less Than or Equal contact)
Besides these instruction the BRX PLC will also have compare instructions for the built in real time clock of the system. We will be looking at these instructions along with some programming examples. As a system integrator, this ability can prove very useful to you in the field when commissioning your automation system.
Lets get started with the BRX PLC Compare Instructions. Continue Reading!

BRX PLC Counters

A majority of the programmable logic controller (PLC) programs will include a counter instruction. The BRX series of programmable logic controllers have several different counters available for your program. There are five different basic counter instructions in the PLC. The memory area for counters (CT), include the Counter PVs (Present Values) Counter SVs (Set Values) and the Counter Completion Flags. The default size of the counter area is CT0 – CT255. This size can change to the amount that we need for our program. Please see BRX PLC Numbering Systems and Addressing on how to change the memory configuration of the controller.
We will be looking at the counter instructions in the BRX PLC along with some programming examples. As a system integrator, this ability can prove very useful to you in the field when commissioning your automation system. When dealing with counters, we need to look at timing charts. The Secret of Using Counters is a good refresher on using timing charts.
Let’s get started with the BRX PLC Counters. Continue Reading!

BRX PLC Timers

A majority of the programmable logic controller (PLC) programs will include a timer instruction. The BRX series of programmable logic controllers have several different timers available for your program. There are nine different basic timing instructions in the PLC. The memory area for timers, include the Timer PVs (Present Values) Timer SVs (Set Values) and the Timer Completion Flags. The default size of the timer area is T0 – T255. This size can change to the amount that we need for our program. Please see BRX PLC Numbering Systems and Addressing on how to change the memory configuration of the controller.
We will be looking at the timer instructions in the BRX PLC along with some programming examples. As a system integrator, this ability can prove very useful to you in the field when commissioning your automation system. When dealing with timers, we need to look at timing charts. The Secret of Using Timers is a good refresher on using timing charts.
Let’s get started with the BRX PLC Timers. Continue Reading!

BRX PLC Online Editing and Debug Mode

Our first program for the BRX PLC involved a start stop jog circuit. We will now use the Do-More Designer Software to modify this program while the PLC is scanning the logic. This is referred to as online programming or online editing. As a system integrator, this ability can prove very useful to you in the field when commissioning your automation system.
We will also be using the special Debug Mode of the software to monitor the ladder logic status and bits on a scan by scan basis. Forcing the inputs and outputs, we will control the execution of the PLC scan. This is a great feature of the Do-More Designer software.
Here is a link explaining the logic behind our circuit.
How to Make a Start Stop Jog Circuit in a PLC
Let’s get started. Continue Reading!

BRX PLC Monitoring and Testing the Program

Our first program for the BRX PLC involved a start stop jog circuit. We will now use the Do-More Designer Software to monitor, test and modify this program. As a system integrator, this ability can prove very useful to you in the field when troubleshooting your automation system.
We will be monitoring the ladder logic status and bits. Changing the bit status will be done by forcing the inputs and outputs.
Here is a link explaining the logic behind our circuit.
How to Make a Start Stop Jog Circuit in a PLC
Let’s get started. Continue Reading!

BRX PLC First Program

We will now look at writing our first program for the BRX PLC. The Do-More Series allows us to write programs online or offline with the PLC controller. The series will also allow us to do online editing. We can change program information and download the new program between scans of our controller. As a system integrator, this ability can prove very useful to you in the field when troubleshooting your automation system.
Our first program will be the start, stop, jog circuit. Here is a link explaining the logic behind the circuit.
How to Make a Start Stop Jog Circuit in a PLC
Let’s get started. Continue Reading!

BRX PLC Numbering Systems and Addressing

The BRX PLC like all of the PLCs in the Do-More Series use strong data typing. This means that there are fixed memory structures to work with in your program. Errors will be displayed if you try to put the wrong type of value in the memory location. The data structures will automatically assist you in your automation system.
Memory can now be as flexible as you want and need. You can define and allocate all the data memory the way you want it up to specific maximums. As a system integrator you determine what best fits your automation framework.
We will be looking at the addressing and numbering systems in the BRX Series PLC. Let’s get started. Continue Reading!

BRX PLC Establishing Communication

We will now use the Do-More Designer software to establish communication with the BRX PLC. This is the same software that we used in the Learn PLC Programming Fee Video Series. Using the Do-More Designer software, we will communicate via USB, RS485 and Ethernet. These three methods will allow us to communicate to our BRX PLC in order to program or troubleshoot this controller. Once we have established communication we will then look at updating the firmware in our controller. Let’s get started. Continue Reading!