About this blog
Tools and technology for motion control engineers designing for electrical and mechanical systems
Electric Motors whitepaper
Electric motors, whether designed to operate on ac, dc, or both types of current, come in numerous shapes and sizes. All electric motors have one goal in common: to convert electrical energy into mechanical motion. Whether the application uses a general-purpose standardized electric motor or a motor intended for a specific task, the selection process must satisfy the dynamic requirement of the machine on which it’s applied without exceeding the motor’s rated temperature.
Bipolar chopper drive circuit III: Controlling current
We left off with the last blog explaining that the “voltage waveform at Sense Resistor” in our schematic shows what the voltage levels would look like as the motor is micro stepped. There are discrete changes in the signal, a staircase up and down, as the DAC converts the digitized signals from the “current level control.”
MDrive EtherNet/IP integrated all-in-one motion systems for industrial automation
Video of North American Sales Manager Paul Kling discussing MDrive EtherNet/IP at MD&M West.
MDrive EtherNet/IP motion systems feature integrated motor, drive and
programmable I/O with standardized IP addressing, eliminating complicated wiring and programming of traditional multi-drop systems with RS-485 communications. These compact, low-cost products are ODVA conformance tested and will interface with many manufacturer systems including Rockwell, Omron and Schneider Electric.
Bipolar chopper drive circuit II: Calculating current
We’re continuing our discussion about bipolar chopper drives and I’ll repeat the basic schematic of it here for ease of discussion. We also left off with +V being powered with only a one volt power supply. That’s not very practical, since most control logic requires something like 5 or 10 volts or higher to operate properly. But hey, we’re trying to explain the drive operation, not the control logic.
Bipolar chopper drive circuit
In today’s blog we’re going to examine a bipolar chopper drive, a common method for precision current control in stepper motors. The simplest way to take a look at its operation is by using a basic schematic of it.
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The case for Industrial Ethernet III: EtherNet/IP™
The last post in this series we examined the major protocols used for automation and control in industrial Ethernet networks. Today we will examine the protocol with highest percentage of industry usage: EtherNet Industrial Protocol, or EtherNet/IP™.
EtherNet/IP™ was introduced by Rockwell Automation in 2001. Over the last 9 years it has grown into the most widely used industrial Ethernet solution for factory automation. EtherNet/IP provides a complete set of services and messages for applications such as:
Evolution of the control electronics
The last blog described how, by controlling the current magnitude in a stepper motor’s winding, we could create smaller steps or micro steps. In this blog, we’ll take a look at the evolution of the control electronics that has made this possible.
The motor that we’ve been “using” in our previous discussions is rated at one amp, one ohm and one millihenry, values that I picked out of the air to make this discussion simple.
The Case for Industrial Ethernet II: Protocols
In the last posting we took the 5000 foot view of industrial Ethernet and examined why using it for industrial networks is such a good idea. In this posting we want to zoom in and drill down into what makes Ethernet devices play nice together on an industrial network: Protocols.
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Stepper motor basics: Half and Micro stepping
In the last posting we explored the two-on full stepping sequence. In this edition we will look at how we can control the motor current to allow us to divide the full 1.8° steps in to 0.9° half steps, and even smaller increments called microsteps. The half step sequence produces a finer step resolution of 0.9 degree steps or 400 half-steps per revolution.
The case for industrial Ethernet
When the Ethernet standard (IEE802.3) was first adopted in the mid-1980s it was considered unsuitable for industrial automation networks because of its non-deterministic nature. Networks using RS-485 and RS-232 ruled the industry.