Introduction to Allen-Bradley PowerFlex Drives With Ethernet/IP

Variable frequency drives, or VFDs, are quickly becoming one of the most common methods of motor control, especially when speeds need to be carefully controlled or to provide a softer startup for larger loads or when many motors are starting at once. 

The technology behind the drives has become more advanced while at the same time becoming more affordable. Advanced features, control algorithms, and connectivity solutions that once were sold as a premium add-on are now standard on most drives.

 

Figure 1. Allen-Bradley PowerFlex 525 Low Voltage AC Drives. Image used courtesy of Rockwell Automation.

 

Allen-Bradley PowerFlex

The Allen-Bradley PowerFlex line of drives (by Rockwell Automation) is one of the most popular VFD series in North America, and is among the leading manufacturers supplying applications around the globe. The entire Allen-Bradley PowerFlex line includes hundreds of configurations, including size, input/output voltage, and application.

The interface options across the line of drives remain very similar, but for simplicity, this article will focus on the PowerFlex 525 series to avoid any discrepancies there may be between the different models.

This particular family, PowerFlex 525 AC Drives, offers a standard yet modular design with built-in Ethernet/IP communications and USB programming. The 525 series is a smaller drive, but it offers a decent power output range from 0.5 to 30 HP, and input voltage classes from 100 to 600 volts (1-phase for smaller voltages). However, the standard features and functionality provided by this drive family are huge.

 

Conventional Hard-Wired Control

Although networking is the modern standard, the PowerFlex 525 drive does include all of the conventional hard-wired control options, typical of most variable frequency drives. This can be used as a primary or secondary control backup option to Ethernet/IP control with the proper configuration. 

 

Figure 2. PowerFlex 525 Control I/O Wiring Block Diagram. Image courtesy of Rockwell Automation.

 

The hard-wired control options include start/stop functions, direction control, and auxiliary digital inputs that can be programmed to pre-select ramp rates and/or speed setpoints, to name a few. There are also hard-wired analog input and output options, like most other drives. 

Analog options include 4-20 mA, 0-10 VDC, or potentiometer inputs along with 4-20 mA or 0-10 VDC analog outputs. The PowerFlex 525 also includes safety-rated inputs for emergency/safety trips.

If you are only interested in starting and stopping a motor and controlling speed once ("set it and forget it"), this conventional hard-wired control may be enough. However, suppose you want to access more features and take advantage of the integrated programming and monitoring with a ControlLogix or CompactLogix controller. In that case, utilizing the standard built-in Ethernet/IP communications is almost certainly the way to go.

 

Configuring and Setting up the Drive

There are several options for configuring and setting up the drive. The first and most basic option is to use the drive keypad. This method is cumbersome, as with any other drive, but it is helpful if you need to make a quick change and do not have one of the other options available.

Most other drives support this same keypad parameterization method, so it will be very familiar if you have configured drives before. This is not the recommended method for setting up an advanced drive application, but getting the IP address set with this method might be very helpful for the initial connection.

The second method for setting up and configuring the drive is through Rockwell Automation’s Studio 5000 programming software. With this method, you need to have the IP address set, or use the default IP address.

Once the IP address is set, you can add the drive to your communications tree in your ControlLogix or CompactLogix configuration. This is very similar to adding any other communications module that you may have already had to add to your program. 

Once communication is established, you can connect directly to the drive-through Studio 5000 and change parameters directly in the drive without having to use the keypad. This method is beneficial if the drive is already installed and powered.

 

Figure 3. PowerFlex 525 parameters dialog via Studio 5000 software. Image used courtesy of the author

 

The third option is to use the Connected Components Workbench (CCW) software from Rockwell Automation. The software is free and can be downloaded from the Rockwell Automation website. 

The advantage of using the CCW software is that you can configure and download to the drive before it is even installed or powered on. The PowerFlex drives have a removable control module that can be powered with a standard USB cable from your laptop or desktop PC. Simply connect the USB cable to the drive and your PC with the CCW software, and you can configure all parameters of the drive.

 

Figure 4. PowerFlex 525 status/configuration dialog via Studio 5000 software. Image used courtesy of the author

 

The benefit of the removable control module is that the electrical installation crew can take the power base of the PowerFlex and continue with the installation of the drive while you are configuring the control module from your desk.

For more detailed steps on any of these configuration methods, see the following publications: PowerFlex 520 Series Quick Start Guide or PowerFlex 525 Ethernet/IP Adapter Guide.

 

Ethernet/IP Control

Ethernet/IP control of the drive is, by far, one of the most useful and flexible options for control of the PowerFlex drives. Once the IP address is set and the drive has been added to your program using Studio 5000 software, all drive parameters and configuration options are available via the software.

The drive parameters that you typically set via keypad are conveniently available for configuration using Studio 5000, but take care to note that some parameters must be set while the drive is in Stop mode, and some require a drive restart before taking effect. In addition to the standard Ethernet/IP communications that comes with the drive, Device Level Ring (DLR) redundancy can be added as an option.

Whether you use the redundancy or not, the connection to the drive is as reliable as remote I/O connected over the same network, as it uses the same methodology. Drive speed, current, temperature, voltage, and a host of other parameters are now available for use inside your CompactLogix or ControlLogix program. There are also several Add-On Instructions and faceplates available that integrate nicely with the Ethernet/IP interface to the drive.

For use with PLCs from other vendors, an EDS (electronic datasheet) file and descriptions of the command words are supplied by Rockwell.

For more information on the Allen-Bradley PowerFlex line of drives, see the Rockwell Automation website or, more specifically, the Rockwell Automation product brochure, which provides a comprehensive overview of the features and capabilities of the family of drives.

 

Revised. Original article published Jan 2021.