Latest PLCs & PACs Technical Articles

One of the most considerable risks in aging control environments is that eventually, spare parts become obsolete and…

One of the most considerable risks in aging control environments is that eventually, spare parts become obsolete and unavailable, and the lack of an upgrade plan can turn a simple failure into a catastrophe.

Credited with coining the name ‘PLC’, Allen-Bradley and parent company Rockwell Automation are major players in the…

Credited with coining the name ‘PLC’, Allen-Bradley and parent company Rockwell Automation are major players in the world of control systems. Learn how the hardware platforms have evolved into the familiar modern configurations.

The timer is a fundamental function of ladder logic programming. In this article, we discuss on- and off-delay as well as…

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 has a wide range of applications and helps to match output values to their real-world applications. Most…

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.

What if you could control the end position and the speed of a hydraulic actuator accurately with just a simple signal?…

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.

Even with the most reliable networks, network outages are inevitable for a host of reasons, and managing these outages in…

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.

Allen Bradley’s Data Highway Plus (DH+) networking ability is still found commonly in interfaces with legacy equipment.…

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.

Although the are similarities in operating theory, relays and contactors are used in industrial circuits for different…

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.

What’s the difference between a Cat 6 and a Cat 6a cable, anyhow? Ethernet cables must meet certain performance…

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.

In the first article of this series, we investigate Siemens as a major PLC manufacturer, learning about the hardware,…

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

Two common methods exist for driving induction motors with VFDs - linear scalar control, which is often labeled as V/f,…

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.

Using an ADC can be very useful when dealing with analog devices in microprocessors, and a necessity when adding analog…

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?

Advanced features such as programmable limits, diagnostics, and remote configuration are available 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 are used in electrical and fluid-actuated motion devices. They allow extremely precise position,…

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.

Before digital control systems, responses were fairly slow. Push a button, and a motor contactor engaged. These days, the…

Before digital control systems, responses were fairly slow. Push a button, and a motor contactor engaged. These days, the speed of computers introduces some new challenges but brings solutions as well.

Modbus is a communication protocol stemming from the early days of Modicon PLCs, but is still common today. These two…

Modbus is a communication protocol stemming from the early days of Modicon PLCs, but is still common today. These two example implementations of Modbus transactions will get you started.

Inductive loads, such as solenoids and contactors, can cause arcs and failures back into electromechanical switching…

Inductive loads, such as solenoids and contactors, can cause arcs and failures back into electromechanical switching devices, causing costly downtime. The solution is cheaper than you think.

Failures of I/O systems are a common source of headache for control engineers. Troubleshooting those devices that have…

Failures of I/O systems are a common source of headache for control engineers. Troubleshooting those devices that have polarized connections (source vs sink, and NPN vs PNP) is a technique worth refining.

Power delivered to devices can be changed by raising or lowering the voltage and current. But this method does not always…

Power delivered to devices can be changed by raising or lowering the voltage and current. But this method does not always produce intended results. Pulse width modulation (or PWM) can be used to better control variable loads.