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Understanding PLC Program Commands: Timers

Understanding PLC Program Commands: Timers

The timer is a fundamental function of ladder logic programming. In this article, we discuss on- and off-delay as well as retentive timers and define the inputs and outputs required to properly use them.


Scaling Values: Linear Versus Non-Linear Changes

Scaling Values: Linear Versus Non-Linear Changes

Scaling values has a wide range of applications and helps to match output values to their real-world applications. Most scaling is linear, but many of these real-world changes are not quite so simple.


Power for Control Circuits: It’s Not Just Power Supplies

Power for Control Circuits: It’s Not Just Power Supplies

Power supplies tend to get a reputation as one of the most important power considerations of a DC control circuit - but we can’t ignore other key players: power filters, converters, and backup power modules.


Acoustic Monitoring to Detect Hidden Machine Failures

Acoustic Monitoring to Detect Hidden Machine Failures

Hello acoustics, my old friend. I've come to monitor you again. Because a worn-out bearing softly creeping, slowly got worse while I was sleeping. And the vibration that was planted in my brain still remains… Within the sound of Maintenance


Controlling Hydraulic Devices with Open and Closed Loop Systems

Controlling Hydraulic Devices with Open and Closed Loop Systems

What if you could control the end position and the speed of a hydraulic actuator accurately with just a simple signal? Some systems use simple open/close valves, but others require far more precision.


Variable Frequency Drives: Managing Network Outage Responses

Variable Frequency Drives: Managing Network Outage Responses

Even with the most reliable networks, network outages are inevitable for a host of reasons, and managing these outages in VFD systems becomes critically important.


How-To: Implementing a Data Highway Plus (DH+) System

How-To: Implementing a Data Highway Plus (DH+) System

Allen Bradley’s Data Highway Plus (DH+) networking ability is still found commonly in interfaces with legacy equipment. Understanding this network structure can bridge the gap between old and new systems.


Contactors versus Relays - Differences and Applications

Contactors versus Relays - Differences and Applications

Although the are similarities in operating theory, relays and contactors are used in industrial circuits for different specific applications, and should not be used interchangeably.


The Cat’s Out of the Bag - Demystifying Network Cables

The Cat’s Out of the Bag - Demystifying Network Cables

What’s the difference between a Cat 6 and a Cat 6a cable, anyhow? Ethernet cables must meet certain performance standards, and these standards can be quite confusing at first glance.


Hysteresis - Error and Compensation in Control Systems

Hysteresis - Error and Compensation in Control Systems

Hysteresis is a term introduced in basic control system courses and listed on sensor datasheets, but the terms is not often understood, with error deriving from both the system itself as well as the sensor.


Comparing Mechanical vs Hydraulic Forces

Comparing Mechanical vs Hydraulic Forces

In honor of May the 4th, Star Wars Day, we compare the sources and applications of the two most common force-delivery systems - mechanical and hydraulic.


Siemens SIMATIC PLCs - Hardware History

Siemens SIMATIC PLCs - Hardware History

In this first of an upcoming series, we investigate Siemens as a major PLC manufacturer, learning about the hardware, software, and key applications of each product lineup.


Circular Economy - Manufacturing to End User… And Back

Circular Economy - Manufacturing to End User… And Back

‘Reduce-reuse-recycle’ is a common slogan for promoting reduction of waste associated with end use of materials. But a circular economy model includes manufacturing processes and raw materials as well.


Defining Scalar and Vector Control in VFD Outputs

Defining Scalar and Vector Control in VFD Outputs

Two common methods exist for driving induction motors with VFDs - linear scalar control, which is often labeled as V/f, and vector, or field-oriented control, which can be a bit more complex to understand.


How to Use Analog to Digital Converters in a Control System

How to Use Analog to Digital Converters in a Control System

Using an ADC can be very useful when dealing with analog devices in microprocessors, and a necessity when adding analog devices to an industrial controller. But once you connect the hardware - what next?


Dynamic Braking Resistors for Motor Control Applications

Dynamic Braking Resistors for Motor Control Applications

Large DC and AC motor drives often provide terminals for installing a braking resistor. What are these resistors, and how do they slow down a machine? What hazards and cautions must be considered?


Introduction to Safety Relays

Introduction to Safety Relays

Redundancy and safety are often seen together in industrial safety systems. Safety relays monitor emergency devices to switch contacts based on status - but what makes them different from normal relays?


Mechanisms of Linear Sensing and Linear Encoding

Mechanisms of Linear Sensing and Linear Encoding

Linear sensors use electrical means to determine their position. Common linear position sensors are resistive, inductive, capacitive, and many rely on a property called magnetostriction.


How-To: Programming with IO-Link Devices

How-To: Programming with IO-Link Devices

Advanced features such as programmable limits, diagnostics, and remote configuration are available with IO-Link devices. Learn how to connect an example IO-Link block into an actual PLC project.


Linear Position Sensors - Control is Only as Precise as the Feedback

Linear Position Sensors - Control is Only as Precise as the Feedback

Linear position sensors are used in electrical and fluid-actuated motion devices. They allow extremely precise position, velocity, and acceleration control, and provide feedback to ensure product quality and tolerance compliance.