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Counters manufacturing PLC PLC Basics PLC Learning Productivity 2000 Productivity Suite Scan

Productivity 2000 PLC Ladder Logic Counter

Most programmable logic controller (PLC) programs will include a counter instruction. The Productivity 2000 Series PLC has two different counter instructions for your program. These can be used in several different ways to adapt to your application. Basically, counters are used to count up or down to a specific limit. When the limit is reached, the output is turned on.
Productivity 2000 PLC Ladder Logic CounterCounters can be made from a few different instructions from the PLC. The math instruction uses the one-shot (leading edge) input to add 1 to an internal register to keep track of the counter’s value. A comparison is used to compare this counter value to a set value (SV). The output is turned on if it is greater than or equal. Another input is used for the reset of the counter value. Copy is used to move the reset value into the counter value. This reset will usually override the counting application. Breaking down the counter’s essential operation will help us understand our application and how we can utilize counters in our automation programs.
PLC Ladder Logic Programming Sample CodeThe productivity suite software has Simple Counters (SCNT) and the Counters (CNT) instructions.
Productivity 2000 PLC Ladder Logic CounterWe will be reviewing these instructions and looking at how to implement them in our ladder logic program. Let’s get started.

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Articles BRX Do-More Counters Do-More Do-More Designer Inputs Outputs PLC PLC Basics PLC Learning Scan Timers

Timing Diagram NOT Just Used for a Timer

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.
Timing Diagram NOT Just Used for a Timer
This visual method is an excellent way of understanding how the PLC ladder logic functions. We will discuss a timing diagram and how it is used for timers, counters, and ladder logic. This will help in understanding or troubleshooting your PLC programs. Let’s get started.

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Articles Do-More Inputs Outputs PLC PLC Basics PLC Learning Scan

Ladder Logic (NO) Contact – 3 Things to Know

Normally open (NO) contacts or inputs in the PLC ladder logic program do not mean the same as a wired normally open switch. NO contacts on the ladder logic provide the logic condition for the rung to turn on the output.
Ladder Logic Normally Open (NO) Contact - 3 Things to KnowWe will be looking at three things about the normally open (NO) contact on our ladder logic program. The normally closed NC ladder logic contact will also be discussed at the end. Let’s get started.

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Communication PLC PLC Basics PLC Learning Productivity 1000 Productivity 2000 Productivity 3000 Productivity Suite Scan

Productivity 2000 Series PLC Online Programming

The Productivity Suite Software allows us to modify our existing program and execute the new code without stopping the scanning of the PLC. This is referred to as online programming or editing. We change the ladder logic code and when we save it to the PLC, the current scan of the PLC is held until the new code is written into the unit. It then releases the scan and our new program starts to execute. This happens in milliseconds so our process can continue to operate.
Productivity 2000 Series PLC Online ProgrammingWe will be taking our existing Start / Stop circuit from last time and add a Jog input using online programming. Changing the program online is a common method of programming. The documentation will also be changed during this online program change. Let’s get started.

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BRX Do-More Do-More Inputs PLC PLC Basics PLC Learning Scan

BRX Do-More PLC High-Speed Input Pulse Catch


The High-Speed Input Pulse Catch will set an output that can be seen by the PLC ladder logic scan in response to an input pulse. Inputs that are too fast to reliably be seen by the ladder logic scan time will be seen.
BRX Do-More PLC High-Speed Input Pulse CatchThe BRX Do-More series of programmable logic controllers have built-in high-speed inputs. These inputs can function in Counter, Timer, or Pulse Catch modes. Every CPU will have either 6 or 10 high-speed inputs (HSI) available depending on the model. These inputs can be used for input frequencies from 0 to 250Khz. 250Khz represents 250000 input counts per second that can be coming from devices connected to your PLC like an encoder. Due to the speed of the inputs, they function on the BRX Do-More PLC asynchronous with the PLC scan time.
We will continue looking at the high-speed inputs on our BRX Do-More PLC, by looking at the pulse catch mode. The pulse catch mode will be set up using the Z phase of our incremental encoder. Pulses will be counted using the input directly in the ladder logic and using the pulse catch bit. Comparisons will be made between the two counts and an output will be turned on when different. Let’s get started.

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PLC PLC Basics PLC Learning Productivity 1000 Productivity 2000 Productivity 3000 Productivity Suite Scan

Productivity 2000 Series PLC Debug Mode

The productivity suite programming software has a debug mode. This will allow you to view and control the rung execution on your ladder logic code. These programming tools allow you to troubleshoot, find, and correct errors in the PLC programming logic.
Productivity 2000 Series PLC Debug ModeWe will be adding a couple of rungs to our exiting start-stop circuit we created last time in our productivity 2000 PLC. Using the debug mode we will explain the scan of the PLC and use these tools to sequence the logic. Let’s get started.