Lin Engineering

Advantages of the R325P Microstepping Driver

Hero image
May 27, 2013

Advantages of the R325P Microstepping Driver

The R325 is the most accurate microstepping driver in the World, merging the needs of performance and low cost. Our engineers have scrupulously designed this 256 microstepping driver to meet the needs of customers today. The R325 can handle +12 to 48VDC input Voltage, and supplies phase currents of 0.25 to 3.0 Amps Peak. Selectable step resolutions from Full, 2x, 4x, 8x, 16x, 32x, 64x, 128x, and 256x microstepping are available. Three optically isolated inputs and one optically isolated control output can be used for step, direction, disable/enable, and fault detection, respectively.


Microstepping, run and holding currents, and a test mode can be changed via dip switches, yet programming and storing these parameters may be more practical during mass production. A unique feature of allowing users to choose between dip switches and RS485/USB communication enables easy implementation for first time and OEM users.

 

How is the R325 accurate? Let’s first look at what makes a Bipolar Microstepping Driver not accurate. Stepper motors have a natural tendency to want to move towards their full step ON position. This magnetic pull is called the detent torque of the motor, which causes a jerking motion as the motor nears these positions. In a bipolar stepper motor, one phase will have 100% current and the other phase will have 0% current (this is what we’ll call the zero-crossing point). Phases A and B are 90° offset and both have a sinusoidal current waveforms.

Content image
Figure 1.1

Drivers that output a perfect sinusoidal current waveform will not have perfect accuracy. Engineers in the Motion Control Industry have gone through trial and error, tweaking the current sine waves in order to alleviate the “jerk” that the motor makes as it is forcefully pulled towards the zero-crossing spots. However, altering the waveform can greatly affect other areas of the driver’s performance.

 

Since these zero-crossing spots are sensitive to the minimal amount of change, the R325 outputs the right amount of both holding and running current into the motor to overcome the motor’s detent torque. The following graphs use the same step motor to run the step-to-step tests. The R325 and a comparable driver were both set to 64 microstepping, the shaft of the motor was aligned to an encoder which graphed the position of the motor over time. Thus, a perfectly accurate step motor and driver combination would show a straight line, signifying an even amount of degrees in between each step.

Content image
Figure 1.2 Comparative Driver
Content image
Figure 1.3 Close up at the Zero Crossing
Content image
Figure 1.4 R325P Driver
Content image
Figure 1.5 Close-up of the zero-crossing. Spike is Eliminated.

News

Latest Updates

Mar 30, 2022
Motor Selection and Sizing
WHITE PAPER

Motor Selection and Sizing

Selecting the right motor for an application can be difficult as each motor has different characteristics and will provide different torque and speeds. When trying to find the right motor and size it's important to keep in mind the application the motor will be used for as well as the power you can provide to the motor.

Dec 02, 2021
Foam Densifier Reduces Lin Engineering's Environmental Footprint
NEWS

Foam Densifier Reduces Lin Engineering's Environmental Footprint

Lin Engineering uses a Foam Densifier to recycle foam and to help reduce our environmental footprint. This machine has helped reduce our overall waste by up to 75%.

Jul 29, 2021
Advantages of Servo BLDC Motors in Automated Guided Vehicles
ARTICLE

Advantages of Servo BLDC Motors in Automated Guided Vehicles

Autonomous Vehicles and Robots are able to navigate on their own allowing them to transport goods from one location to the next on their own. Engineers typically use Servo motors to drive AGVs as they deliver precise speed control as well as position control. But what are servo motors and what makes them good for AGVs?

View All Updates