Gain is the ratio of output to input—a measure of the amplification of the input signal. A common example is the volume button on a stereo. This button controls the ratio of the input signal (received from the radio station) to the output signal (how loud the sound is from your speakers). When the volume is […]
FAQs + basics
FAQ: Why would shaft inertia cause extra steps, and how to prevent this problem?
Inertia affects how stepper motors turn. For example, extra steps and missed steps can happen when a system has inertia mismatch — as detailed in FAQ: How do stepper motors handle inertia mismatch? Another source of missed steps is the motor inertia itself. The motor-shaft inertia is one culprit. This shaft rotates and has a […]
FAQ: What is a pulse rectifier and what kinds are there?
Variable frequency drives are made up of three primary sections: a rectifier, which converts the supplied AC voltage to DC; a DC bus, which stores the DC voltage; and an inverter, which converts the DC power back to AC at the voltage and frequency required by the motor. The most common, and simplest, rectifier designs use […]
FAQ: How to set a stepper motor’s current limit and why is it important?
Edited by Zak Khan || Stepper-motor current limiting serves a few functions. Stepper-motor overcurrent can cause overheating as detailed in FAQ: Aren’t heat and noise common stepper motor problems? At its most extreme, overcurrent can cause rotor demagnetization. Recall that current effects acceleration — as in FAQ: What are the requirements for stepper motor acceleration? So […]
FAQ: What are the requirements for stepper motor acceleration?
Edited by Zak Khan || Engineers should give thought to acceleration when starting a stepper motor. Simply programming the controller to advance the motor some steps isn’t sufficient for reliable operation. Programming must also account for stepper-motor construction and operation. As mentioned in FAQ: How do I prevent stepper motor stalls? and FAQ: How do stepper […]
FAQ: What kind of torque can I get out of a stepper motor versus other options?
Stepper-motor output torque depends on a few things — including the stepper-motor type; how many poles it has; how fast it runs; and the type of drive supplying electrical power to the motor. For the latter, read FAQ: What is a stepper drive and how do they work? for more information. More specifically, a stepper […]
FAQ: How do proprietary and open-source PC control software programs compare?
The central issue with anything that is programmable is the programming itself. Regardless of whether the system is open source or proprietary, the key to successful control applications is to correctly program the design intent. Capturing the full intent at the start of a project is impossible, especially if the project has not been done […]
FAQ: Why do so many PC controls integrate HMIs?
By Steve Meyer || Previous generations of control relied on Cathode Ray Tubes (CRTs) for information displays as part of programming terminals. Those unfamiliar with CRTs should read the Wikipedia articles and check Google Images for representations of how the CRT works. It is an interesting part of the history of control. CRTs use high-voltage power supplies […]
Choosing between automation technologies based on industrial PC control
Today’s state-of-the-art PC-based controls deliver performance that exceeds most industrial machine-control requirements. Processor power and memory continue to expand — following Moore’s Law and doubling in capability every couple years. What’s more, cost per processor continually declines as performance increases. Whenever control manufacturers update their electronics, it makes more power available to end users. Here’s […]
FAQ: What is tag naming and the point of defining data types with PAC programming?
By Steve Meyer || Tag naming starts with naming the I/O in a control system. The names might only serve as a bookkeeping convenience for documenting in ladder programs, but in the complex environment of today’s PLC and PAC platforms, tag names are more significant. Tag names can serve as a referent for I/O points in totally […]