R701/R710- Powerful Microstepping Drivers now RoHS Compliant!

Lin Engineering, The Step Motor Specialists, are pleased to introduce the RoHS compliant version of their popular R701 and R710 drivers.   
These bipolar step motor drivers operate from 24 to 80 VDC and supply phase currents ranging from 1 to 7 amps.  The drivers also features 10x microstepping, selectable current reduction of 33%, a step frequency of 200 kHz and optically isolated step, direction, and disable/enable inputs. 
For users needing less vibration and smooth performance, the R701 and R710 boast an onboard trimpots that can be adjusted to alter the current waveform coming out of the motor and going into the step motor coils.  This adjustment will decrease the amount of noise and vibration coming out of the motor enabling for smooth motion. 
Please visit the company website at www.linengineering.com for more technical specifications as well as downloadable reference guides and product manual.

SilverPak 23D—Now RoHS compliant and available with Configuration Module

Lin Engineering, the Step Motor Specialists, are pleased to announce the release of their new and improved SilverPak 23D product line.  The SilverPak 23D is a high torque NEMA 23 step motor with an integrated microstepping driver.  The new version of the SilverPak 23D comes with added features such as increased operating voltage range and the ability to use the new Lin configuration module. 
The SilverPak 23D is designed to help reduce overall design time and system cost for a wide array of step motor applications needing high torque and smooth motion.  It is available in three body lengths: 2.52”, 2.96” and 3.89” and is capable of up to 294 oz-in of holding torque depending on the stack size of the motor.  The SilverPak 23D operates from 12 VDC to 48 VDC and the available phase current ranges from 0.3 Amps to 3 Amps peak. This integrated motor/driver combination boasts step resolutions ranging from 2x microstepping up to 256X microstepping and 4 selectable damping modes. The unit also features: optically isolated step, direction and disable/enable inputs; and under-voltage and over-temperature protection.
The SilverPak 23D is now available with the new Lin Engineering configuration module (sold separately).  Users can easily use the configuration module to adjust various parameters of the SilverPak 23D unit.  These parameters include, but are not limited to:

1. Step resolution change via dipswitches on configuration board
2. Run current change via dipswitches on configuration board
3. Hold current change via dipswitches on configuration board
4. Damping modes for smoother motion
5. Selection of sensing the step pulses on the rising edge or falling edge
6. Selection of sensing the direction change on the rising or falling edge
   

R208 Microstepping Driver—Higher Performance and Affordability in 1 small Package.  Now RoHS Compliant

Lin Engineering, the Step Motor Specialists, are pleased to introduce the RoHS compliant version of the popular R208 Microstepping Driver.  The R208 is a cost effective solution to high priced drivers delivering uncompromising performance without the hefty price.   

The R208 Driver is compact in design with low power dissipation and automatic current reduction. It is able to provide up to 2.0 Amps of phase current to any bipolar step motor. Users have the option of setting the micro stepping resolution from full step, half step, 1/4 step to 1/8 step.

The R208 drive unit is even able to utilize a 12-24 VDC power supply in order to produce constant sinusoidal current waveforms.  Additionally, the driver features optically isolated step, direction and disable inputs, built-in thermal shut down and efficient current control features. 

The two newest features of the R208 are:

1. The ability to recognize step pulses from the controller from either the rising edge or the falling edge.  This option (which is user configurable) allows for greater flexibility using the R208 with various types of PLCs.    
   
2. The R208 now allows the ability to change the amount of holding current that is applied to the motor.  A cutback current of 23% is the default setting, but can now be changed to 100% of the run current via a dipswitch on the board.

For more information on Lin Engineering's R208 please contact us at 408-919-0200 or email us at sales@linengineering.com.

Step Motor Terminology got you stumped?
Lin Engineering explains the differences between
Amps/Phase and Amps Peak Current.

Step motor terminology can be confusing for all engineers; both at the novice and the advanced level.  With so much technical jargon floating around, it’s hard to stay up to date with everything.  However, getting to know the terminology that is associated with your specific application is of the utmost importance. 

For engineers who use step motors in a current-controlled method, which is the case for almost all bipolar drivers, the amperage is a key component to take into consideration.  When one specification is so essential to the motor’s performance, it is imperative that all terminology that is associated with it is also understood.  In the case of step motors they are almost always labeled with an Amps/Phase rating, also known as Amps RMS or average current.  This might seem simple enough, but then, step motor and driver manufacturers will throw in a term like “Amps Peak” current into the mix and cause some confusion.  So what does this all mean?

Let’s first understand why the current rating is important when using current-controlled systems.  Drivers will control when and how much current each motor phase will receive.  You can imagine it as two switches for the two phases of a bipolar step motor.  These switches will turn on and off in a sequence in order to get the motor to step.  Each change is equal to one step.  Furthermore, with each change, current will flow in the motor (rise) then flow out (deplete) due to the fact that the coils act like storage for power. 

Current ratings stem from overall I2R power and the internal step motor coils have a resistance rating.  Since this is based on the windings, we choose I, current, to be a value such that I2 R power does not exceed standard wattage ratings per motor size.  Beyond the standard ratings, you’ll end up with a burnt motor.

Finally, what exactly is Amps/Phase, Amps RMS and Amps Peak?  Earlier we mentioned the switching sequence in order to make a motor step; the sequence for both A and B is shown below.  Recall in circuits, “negative” simply means current is flowing in an opposite direction.

*Another way of depicting the ON, -ON, and OFF, -OFF is to show it as Phase A as the X-Coordinate, and Phase B as a Y-Coordinate:

Furthermore, if we plot out the change in current values for the A Phase only, it will look something like this:

What Is RMS Current?

Since the current waveform shown above is continuously changing, we need to be able to communicate what the average current is for that particular step motor.  RMS is a statistical measurement of the magnitude when the values are always changing.

Theoretically, the average amount of current a motor will receive based on the above graphs and charts, is 1.0 Amps RMS.

What Is Amp/Phase?

This tells us how much average current each winding or phase can handle without heating up and burning the motor.  This value is the same value as the Amp RMS rating.  The labels on the motor and the datasheet of the motors will list Amp/Phase.  In our example shown above, the Amp/Phase and Amp RMS values are 1.0 Amp.  The peak value is 1.4 Amp Peak.

What Is Peak Current?

The motor current could potentially reach 1.41 Amps for a split second.  The peak of this graph is at 141%.  This is what peak current is.  Drivers and controller products only care about what the max current will be at any given point, therefore, they refer to current in terms of peak.  Recent changes are being made since most motion control users understand current in terms of what the motor can handle, thus adding both specs on the driver datasheets.

What’s the correlation between it all?

Amps/Phase * 1.41 = Amps Peak current.  Regardless of whether you remember the reason behind the 1.41 value, it’s crucial to understand this relationship because in most manufacturers, drivers only care about what peak value it can output.  And step motors only care about listing the Amps/Phase value.  As long as you understand what the difference is, you will be able to talk in the same language to both driver manufacturers and step motor manufacturers.

Lin Control- New Graphical User Interface (GUI) from Lin Engineering

Santa Clara, CA—October 2007—Lin Engineering, the Step Motor Specialists, are pleased to introduce Lin Control: a new graphical user interface that can be used with their popular motion controller products.

Lin Control is a simple yet intuitive software program designed by Lin Engineering that allows users to set up both motion parameters and execute commands.  Lin Control is very similar to Windows HyperTerminal, but with some key advantages:

1. Users are now allowed to backspace and retype information in the terminal section
2. Current, velocity, acceleration, and microstepping can easily be configured
3. Lin Control comes with a built-in Unit Converter (i.e. RPM to RPS,etc.)
4. A command tree-like structure is available for implementing programs
5. Programs can be saved and uploaded via a text file

Best of all, Lin Control is available at no cost via a simple download from the Lin Engineering website:  www.linengineering.com/LinControl  

Lin Control is currently compatible with the following products from Lin Engineering:

1. R256:  Stand Alone Driver/Controller unit
2. SilverPak 17C/CE: NEMA 17 Integrated Motor + Driver + Controller
3. SilverPak 23C/CE:  NEMA 23 Integrated Motor + Driver + Controller

For more information regarding Lin Control please contact us at 408-919-0200 or email at sales@linengineering.com.

Designer’s Corner Enhanced—Step Motor Selection Made Easier

Santa Clara, CA—May 2007—Lin Engineering, the Step Motor Specialists, are pleased to introduce an enhanced version of their patent pending online step motor selection tool: Designer’s Corner.  In just 3 easy steps, Designer’s Corner will select a motor that will work within your application specifications.  Users now have the ability to enter data based on one of the most common applications below:

1. Conveyer Belt
2. Lead Screw
3. Direct Drive
4. Rack & Pinion

Designer’s Corner is available free of charge at www.linengineering.com.  Best of all there is no software to download; just a simple registration process is required in order to use this innovative tool. After your motor is selected, you can request a quote from a Customer Service Professional.  For a limited time only, the first motor you select using Designer’s Corner can be requested at no charge.    

Q:  How do I know which type of motor I should use? From Peter Boulder, CO

A: Hi Pete,
A common question that can be easily answered.  Generally speaking, you want to use a step motor if you require high torque at low speeds, need precise steps or require the motor to hold in place, or if you want to maintain a consistent amount of torque across an entire speed range.  You’ll want to use a BLDC motor if you require mid to low torque ranges at high speeds, if you need a constant rotation or back & forth movement, or if you want to maintain speed consistently across various torque ranges.  Speeds of 20 RPS are considered low.  Speeds higher than 50 RPS is considered high.

Q: How much power will my step motor consume? From Dana of Boston, MA

A: Hi Dana, ,
Power consumption from a step motor depends on three main components: copper loss, iron loss, and output power in terms of torque at speed.  Copper loss can be calculated based on the electrical specs of your motor: 2*I^2*R (I is current, R is resistance).  Iron loss comes mainly from the power supply, about 5.16 watts if using a 24VDC supply.  And finally, torque x speed x 0.0444, a coefficient, is your output power from the motor.  Therefore it depends on the speed and the torque outputted by the motor.  Also, when the motor is loaded with force, it requires a bit more power as well.  For an easy solution, feel free to use a generalization of V*I (voltage input times current rating of the motor)

Q: How do you determine a step motor's maximum step rate? From Walter of Roseville, IL

A: Hi Walter,
The max step rate depends on how much voltage and current you have available and how big the load it. Generally, the higher the voltage, the higher the speed.