Applications and How-Tos

Spindle motor control with KEB drives

With over 200,000 installed spindle drives, KEB has earned a reputation as the worldwide spindle drive leader.  This post describes some of the reasons KEB is preferred by our CNC, woodworking, and robotic customers.




Spindle Motor Control

KEB drives can run both induction and permanent magnet spindle motors through the adjustment of a drive parameter.  KEB’s robust motor control algorithms mean it can run a variety of different motor designs from all major spindle motor manufacturers.  Basic applications can utilize V/Hz control.  The advantage of V/Hz is its simplicity and ease of commissioning.


Closed loop applications can be solved using KEB’s dual channel encoder interface.  Many feedback formats are supported including: Incremental TTL/HTL, Resolver, EnDAT 2.1/2.2, Hiperface, etc.  Tool change and orientation functions can be programmed in the drive.  This possibly allows the PLC or controller to be removed from the system.


Closed loop drives offer the additional feature of torque limits.  Different sets can be programmed which allows a number of different torque limits to be set to match the motors operating characteristic – ensuring that the motor does not become overloaded.


KEB’s unique SCL™ and ASCL™ (Sensorless Closed Loop, Asynchronous Sensorless Closed Loop) control technology can be used to provide closed loop performance without the need for encoder feedback.



Spindle Performance

Newer drive platforms like the S6 feature a fast current control loop of 62.5µs.  This provides excellent spindle motor performance and, ultimately, a better final product.


KEB drives are offered in switching frequencies up to 16kHZ with output frequencies up to 1667 Hz for high-speed applications.  This allows motor speeds in excess of 100,000 rpm while keeping motor noise and heating to a minimum.


KEB drives are offered in sizes from fractional horsepower up to 1000 Hp.  For 3 phase installations, 230VAC and 460VAC voltage classes are available.  Additionally, a single phase 230VAC variant is offered.



Ethernet On Board

Although KEB drives support a variety of different communication protocols like Ethernet/IP, Powerlink, and Profinet  –  we have standardized on EtherCAT.  EtherCAT communication offers excellent real-time performance, is an open technology with many vendors and members, and offers tremendous value for its performance.

S6 with On-board EtherCAT

EtherCAT is well suited in demanding, high-performance applications.  For example, the S6 platform supports a 500 µs scan time for up to 8 parameters (up to 32 bytes).  The EtherCAT process data can be used to send a home or orient command to the drive.  This can be used for a basic home start or for a tool change.  The S6 drive will use the zero pulse from the encoder to position the spindle for a tool change.


Combivis Wizard for easily configuring EtherCAT Process Data


Positioning can also be done over EtherCAT.  The desired position (position counts either relative or absolute) can be written to the drive directly over EtherCAT.  Alternatively, predefined positions can be stored in the drive and the PLC can select which position the system should move to and send that signal over EtherCAT.



Functional Safety

Along with the benefits of EtherCAT mentioned above, KEB drives also offer functional safety options.  Safe-Torque-Off (STO) is offered as standard.  More advanced Safe Motion functionality according to ISO 13849 is available, including: SS1, SS2, SOS, SLS, SLP, SLI, SDI, SSM.

KEB Drive Safe Motion – Per IEC 61800-5-2


One advantage for moving Safe Motion into the drive is that the drive’s high power does not need to be removed in certain situations.  An example would be when an operator opens the machine tool door to clear debris.  Traditionally, all power would be cut from the drive to the motor does not unintentionally start.  But this requires that operator waits so the drive bus capacitors can discharge and recharged again.


With KEB’s SIL3 Safe Motion functions, this same functionality can be achieved through our Safe control card and 24V inputs.  High power remains connected which ultimately allows for machine operation.


See why KEB is the spindle drive leader, discuss your application with a KEB engineer today.

Remote Access to Allen Bradley Rockwell PLCs

A few common questions I get from customers: Does the C6 Router support Ethernet/IP, DH+? Can the C6 Router connect to my ControlLogix, MicroLogix, CompactLogix, etc.? Can I get remote access to Allen Bradley PLCs? The answer to these questions is yes! The C6 Router used in conjunction with Combivis Connect software can setup a secure end-to-end VPN connection to your Allen Bradley PLC’s.



This blog post will review the steps needed to establish remote access with a C6 industrial router to a Allen Bradley PLC and RSLogix software.


Step 1: Internet Access to Router


In order for Combivis Connect to setup a VPN connection, the C6 router must have internet access. The router acts as a VPN server and assigns the user PC an IP address within the VPN network ensuring a direct end-to-end connection using secure TCP/UDP ports and SSL/TLS protocol.


This can be accomplished two ways. Either by configuring the WAN interface or configuring the modem with a standard SIM card.


Remote access allen bradley WAN config allenbradleyconnect_modem


Step 2: Configure LAN Interface


Assign the LAN interface an IP address within the local PLC network. All Allen Bradley PLC’s using EtherNET/IP, DeviceNet, ControlNet, etc. belonging to the subnet of the LAN interface can be reached via the VPN tunnel.



Step 3: Serial Port Configuration


Allen Bradley PLC’s using serial protocols such as DF1, DH+, or DH485 can also be remotely monitored and programmed. Combivis Connect uses a virtual serial adapter to map to the physical serial port of the C6 router. Select the correct port setting.



The C6 Industrial Router supports remote connection to legacy PLC-5 and SLC 500 series PLCs as well

Step 4: Register Router to Domain


Before the C6 router can be connected, too, the router must be assigned to the domain of Combivis Connect. Assign the router a name, and apply the settings.



Step 5: Connect to C6 Router



Once the router has finished rebooting, the router can be connected to. Simply select the Connect button to establish a connection. Once the router is connected the all Allen Bradley PLC’s can be accessed via the VPN tunnel.




Step 6: Remote Access with RSLogix


At this point RSLogix can go online with the PLC and program in desired Controller operating mode.






Remotely accessing Allen Bradley PLC’s is easy and reliable using Combivis Connect and the C6 Router. There is no lengthy setup process or complicated communication driver setup to access your Allen Bradley PLC’s.


Are you interested in remotely accessing your Allen Bradley PLC’s with a C6 Router? Contact a KEB controls engineer today to discuss.


Derating induction motors

KEB Servo Motors

Synchronous motors like KEB’s Servo Motors can be adjusted for derated speeds easily

When looking at different applications that use variable frequency drives (VFDs) and motors, there are some that require the motor to be run at slower speeds than the rated motor speed. One example of an application that might require this would be a relatively slow elevator that doesn’t need to run at the full motor rated speed. Sometimes motor manufacturers will provide a set of motor data with the derated application data included. For certain applications with VFDs this derated motor data is fine to enter into the drive, but for others it can cause major issues, particularly derating induction motors.


For permanent magnet gearless motors (synchronous motors), derating the motor data in the drive is acceptable. These motors run at their synchronous speed, so there is a linear relationship between the motor rated speed, frequency, and voltage as well as between torque and current. If derated motor data for a permanent magnet motor is entered into a KEB F5 drive, then the motor tune function can be completed as usual and the drive will operate the motor as intended. The motor tune will still measure the different properties of the motor correctly and create a motor model internal to the drive that is used to control the operation of the motor at various speeds.


Helical bevel gearmotor - K unit

Induction motors need additional configuration to run at derated speeds

Induction motors (asynchronous or squirrel-cage motors) behave differently than permanent magnet motors. Due to the design of the motor, it operates at a rated speed less than the synchronous speed, by a difference known as the slip speed. Because the motor has this slip speed, there is not a linear relationship between the motor speed and frequency (based on the number of motor poles). The slip is what allows an induction motor to produce torque. When running an induction motor, the drive provides magnetizing current to the motor in order to maintain the magnetic field that provides the necessary torque. The drive also provides phase current to the motor that allows the motor to run. If there is an application where a derated rated motor current value is entered into the drive, the drive will correspondingly limit the magnetizing current in the motor model internal to the drive. This causes the motor to run with more slip to compensate for the lower magnetic field, which actually results in a higher operating current. This may seem counter-intuitive that lowering the motor rated current in the drive would result in a higher operating current. However, due to the lower magnetizing current in the motor model, derating the motor data for an induction motor would lead to an increased phase current draw.


The best thing to do with an induction motor that is intended to operate at a lower speed while using a KEB VFD is to enter the actual nominal rated motor data into the drive, including the full load rated motor speed (not the synchronous speed), as opposed to the derated application data. With this data, the drive can create an accurate motor model without limiting the magnetizing current.   In this case, the drive must be sized according to the nominal motor rated current.  This is due to a limit of 110% of inverter rated output current which can be entered for motor rated current.  So, it may not be possible to downsize the drive based on derated motor current for induction motors.


If you need assistance with derating an induction motor, give us a call or email and one of our engineers can help you get things running smoothly.

IIoT for analytics – how IoT can be used to improve performance

Centralized control of applications that rely on automation is a huge benefit of the Industrial Internet of Things, and is typically the first thing you’ll hear about when getting a pitch for an integrated system. In this post I’d like to go over another benefit that many installations can take advantage of in order to see increased productivity and lower operating costs, and that is using IIoT for analytics. The data needed for maintenance and optimization has been available for years. With the growth of the internet and networked systems this data is now easier to access and store. But now that we have all of this at our fingertips without ever having to set foot on the factory floor, what do we do with it?


Predictive maintenance and self-optimizing production have been cited as two of the top issues driving increased IIoT adoption in regards to analytics. Both of these issues can be addressed by using data gathered during operation – the key is in finding the right types of data and applying fixes or changes appropriately.


IIoT and maintenance

IIoT for analytics - COMBIVIS Studio

COMBIVIS Studio HMI software from KEB can be used devices in an IIoT setting.


Failure of a single machine or line of machines can range from mildly annoying to catastrophic for business. You might think that a constant need for reactive maintenance might be a sign of IIoT failure, or that it has no place in the centralized control and monitoring. However, keeping track of these types of problems are key to identifying patterns in line faults.


When a critical failure occurs there is a real need for diagnosis so it can be prevented in the future. Programmed machine components, such as drives or PLCs, can log critical data and send it to HMIs using software like KEB’s COMBIVIS Studio HMI. Detailed logs provided by the components will let operators know the state of the machine components just before failure – even if the equipment was damaged. If significant delays are suspected of leading to a lack of happy customers, logs can show the amount of downtime in relation to failures and machine states and pinpoint the component that needs to be addressed.


Another way IIoT can be used as part of reactive maintenance is setting up alert systems so when failure or downtime occurs it can be dealt with swiftly. KEB’s C6 Router has the ability to send SMS or email notifications when events are triggered that may require the operator’s attention.


In the past, evaluating each component of a line after a fault could be time consuming and sometimes dangerous. Now that the data is gathered and stored in a central system, it can be analyzed without having to put on a hard hat and safety glasses, and predictive maintenance can be implemented. Look for patterns in machine states and set alerts to notify operators when thresholds are crossed that signify a possible failure. Logs can be kept for “hours on” so an accurate time-table for maintenance and replacement can be kept. Accurate tracking of machine operation can also help pinpoint aberrations in performance both sudden and chronic.


IIoT and Analytics - C6 Router

Optimizing performance


Throughput and accuracy in production makes customers happy and keeps costs low. By logging key performance indicators you can make changes as needed to optimize production. These indicators are typically things that would not cause a large failure, but lead to a pattern of lost time and errors in production.


You may have a standard time estimate for production of a product that has a built-in assumption of 80 minutes of production downtime per week. In reviewing logs of average downtime duration, you discover that downtime is closer to 120 minutes per week. You can use this info to adjust your lead time estimates and provide better estimates to your customers. Measuring throughput at key sections of production can identify bottlenecks, and power consumption during peak performance periods can help analyze spending requirements.


KEB and IIoT for analytics


KEB has several products in our automation line that collect this useful data, and many others that have the ability to create data for collection and analysis. With top-of-the-line industrial design, 40+ communication drivers, and an integrated EtherCAT master and runtime environment the C6 HMI LC is a fantastic tool for solution for automation. With COMBIVIS Studio HMI and COMBIVIS Connect you can take advantage of KEB’s worldwide, secure network to set up commissioning and monitoring of your system.


IIoT for analytics - COMBIVIS connect
The C6 VPN Router is another product we feel can greatly benefit customers looking to use the internet of things (*note, this only applies to router models with integrated HMI features). It has a rugged industrial design with no fans or moving parts, and comes in extended temperature versions. Cable-free integration can be accomplished with a SIM card on any 2G/3G/3G+ network. These features are perfect for remote installations that are typically not easy or safe to get to. Once the router is installed and paired with COMBIVIS HMI software maintenance and analysis can be done from the office, which means you spend less time at the airport.


KEB drives, like the F5 Inverter, can be linked with the HMI LC or Router and be used to gather the kind of data you would need to apply predictive maintenance and line optimization. Current, voltage, speed, and other measurements can be created during operation and sent to a device capable of logging. KEB has control product specialists right here in Minnesota, so if you have any questions about how you can set up your system to log important operating metrics and key performance indicators feel free to contact us and we’ll help you out.


An intricate or robust IIoT network is not a perfect solution for every application. Smaller lines where the machines have ample space to operate and users have lots of room to maneuver would make maintenance on a single machine from the factory floor quite easy. If the installation is in a climate-controlled facility and just a short walk down the hall rather than a 3-hour flight, the extra networking might be unnecessary. But there are many instances where centralized control can make gathering important info easier. Extreme temperatures, remote locations, tight spaces – consider the amount of effort required to work with these conditions and you may find that you’ll get great ROI on an industrial IIoT setup from KEB America.


Remote access monitoring for Oil and Gas Industry

KEB’s C6 VPN Router is well suited for Oil & Gas applications.  This post describes some of the advantages to using KEB’s VPN Router for remote access monitoring.



The basic functionality of the C6 VPN Router is that it facilitates a remote connection between a user and a PLC.  Since the Router creates a virtual Ethernet or Serial port it can be used with all major PLC platforms like Allen Bradley, Siemens, or Schneider.


Click here, for a 3-minute video describing how KEB’s Router works.

C6 VPN Router – Product Video


Many Oil & Gas installations like pumping stations or storage tanks are off the communication grid.  The Router comes in a few different hardware flavors but the most interesting for remote applications is the cellular version.


The cellular version works on global GSM networks.  This means it will be compatible even if your equipment ships overseas or to exotic locations (assuming a cell network exists).  A user will have to pay for cell data usage but they do not need to invest in a costly radio network infrastructure.  KEB offers various antenna options including one model that is rated for outdoor applications (IP67).

The cellular version makes remote monitoring easy – even for offshore applications



The Router really excels when data logging or remote monitoring is required.  The “HMI” version of the Router includes this functionality built-in to the device.  The Router with HMI includes 4GB of local memory where data can be stored before exporting.


The PLC tags are initially mapped using KEB’s Combivis Studio HMI software.  The data can be exported in a variety of raw formats (e.g. .csv) where it can be manipulated further or used in custom dashboards.  Another option is to use KEB’s HMI software to graph the variables using a built-in trending tool.

remote monitoring oil and gas

Built-in trending and visualization capabilities




Combivis HMI also includes built-in alarm handling tools.  The alarms can help respond to critical events more quickly or plan preventative maintenence. The events can be triggered in a number of different ways (e.g. a set threshold has been reached).


It is also possible to assign priority levels to each alarm.   Then, based on the priority level, specific actions can be programmed – a typical scenario is for an SMS text or email notification to be sent out.

alarm handling oil and gas

Alarm handling dashboard




The Router features a number of security features.  First, the Router has digital inputs that can be used to enable data transmission.  Usually, this means a keyswitch or local enable must be pressed before the Router is activated.  Alternatively, an SMS text could be used to initiate the connection.  The Router also has outputs which can be fed back to the PLC and provide confirmation that the device is in transmit mode.  After the Router and PLC are connected, the data is then transmitted via a 128-bit encrypted VPN connection.


KEB’s CONNECT™ software is used with the Router hardware to make a connection.  CONNECT has a number of features that ensure secure connections.  The software tool has extensive configuration options which allow an administrator to create users.  Each user can be assigned an individual password and expiration dates can be defined.


Custom firewall rules can be made with CONNECT and unique MAC ID and IP addresses can be set.  This ensures only authorized computers or connections have access to the remote PLC.


Finally, CONNECT features an integrated audit trail where user IDs and logins are time stamped and recorded.




Don’t be afraid to put the C6 Router in the field – it was designed for tough industrial applications.  It is housed in a rugged metal enclosure.  It accepts an input voltage between 9 … 36VDC so it can be used with the main control power or battery.


As standard, the Router is operable in temps from 0 to 50°C.  An extended temperature version is available which extends the ratings to -20 … 60°C.

Extended Temperature versions for harsh environments




Are you interested in remotely connecting to your control?  If so, contact KEB today.


Advantages of the KEB F5 Drive for Spindle Motor Control

One application that the features of KEB’s F5 drives are ideally suited for is spindle motor control, such as on a CNC machine. This post describes the benefits and services KEB has to offer after our years of experience in this area.

Benefits in Spindle Motor Control

Variety of Motor Control Options

KEB offers a variety of motor control algorithms that allow the F5 to control the spindle in multiple ways. From the most basic open loop V/Hz control, to the more common closed loop with feedback, to KEB’s Sensorless Closed Loop, there is a control type for all applications.  Both closed loop modes allow for precise speed and torque control, while the SCL can achieve this with no required feedback.

High Speed Applications

KEB Sine FilterThe precision of KEB’s closed loop control is especially advantageous for the high speed applications common with spindles.  The F5 drives offer switching frequencies up to 16 kHz.  Operating a spindle motor with high switching frequencies lowers motor noise, losses, and heating.  The high switching frequency also allows for output frequencies up to 1600 Hz, allowing the KEB drive to control spindles up to 128,000 rpm. Pairing the F5 drive with a KEB Sine Filter provides a true sinusoidal waveform for ideal motor control and efficiency, even at high speeds.

Encoder and Bus Flexibility

The F5 is designed for maximum flexibility for feedback and bus communications options. Both are modular and can be swapped out if another feedback or bus protocol is required, making the F5 a great fit for all systems.


In the case of the feedback board, it has two channels available for a variety of input and output combinations. Options such as TTL In/TTL Out, Resolver In/TTL Out, TTL In/TTL In, or Sin-Cos/TTL Out are all commonly used.  But with over 30 combinations, the VFD can meet most feedback requirements.


The bus communication is handled by the drive’s modular keypad operator.  With over a dozen supported protocols, the F5 can communicate with all major fieldbus networks.  Options range from Ether CAT to Profibus to Ethernet/IP.  Changing protocols is as simple as swapping out the existing operator for the operator of the required fieldbus communication.  One benefit is that all internal drive settings remain the same.

VFD Bus Operator

Additional Control Benefits

In addition to the control and flexibility already listed that makes the F5 ideal for spindle applications, it also has two options that could benefit both OEMs and end customers. The first is the added drive safety functionality of Safe Torque Off (STO) and Safe Stop Level One (SS1) in the new F5-K.  The STO function is a certified hardware/design that requires two enable inputs in order to output torque.  The loss of one of the redundant inputs prevents a system from applying shaft torque. The SS1 is a function that decelerates the drive within an adjusted time before being set to STO.

SS1 – Safe Stop 1 Type B

STO – Safe Torque Off

Finally, KEB offers a ready to go spindle program with both a standard run mode and a tool change/orient mode.  The program is customizable to different motor data, acceleration times, or other application specific requirements.  It allows for a quick and easy startup of the F5 drive with a spindle.

spindle motor control diagram

Click image to view full size diagram.

Power Benefits

Wide Power Range

KEB’s F5 drives also offer a variety of power benefits that make it a great fit as a spindle drive. First, the drives have a large power range, from as low as 0.5 Hp to as high as 1000 Hp.  The drives also come in two voltage classes, the 230V class (Input voltage range of 180-260VAC) and the 400V class (305-528VAC).  The combination of the two voltage classes and the wide power range makes it easy to find the right size drive for nearly all spindle applications.

Multiple Heatsink Options

Another power stage benefit KEB has to offer is the variety of heatsinks. While the F5’s standard air cooled heatsink is acceptable in most cases, some applications can take advantage of the through mount or liquid cooled heatsinks.  The through mount heatsink allows the drive to be mounted so that the heatsink, while still attached to the back of the drive, is outside of the cabinet.  This prevents the energy dissipated by the heatsink from warming up the enclosure.  For additional cooling capacity, KEB offers liquid cooled drives in power sizes of 7.5 Hp and larger.  The liquid cooled drives can also be through mounted, so all of the connections and piping for the liquid is outside of the cabinet and away from the electronics.

Experience with Motor Manufacturers

In addition to all of the benefits the F5 drive has to offer, because of KEB’s years of experience in spindle applications, we have worked with a variety of spindle manufacturers. We have worked with spindles of all power sizes from Alfred Jäger, HSD, Omlat, and a variety of others. Whether asynchronous or synchronous, KEB can run nearly any spindle as efficiently and precisely as the application requires.


There are a variety of reasons to choose KEB as the drive manufacturer for your spindle application. First, the control of the F5 drive has been proven to meet the precise speed and torque control required of spindle drives, even at speeds up to 128,000 rpm.  Secondly, with an expansive power range and multiple voltage classes, KEB has the right size drive for a spindle of any power size.  Finally, KEB is proven.  With years of experience running spindle motors and over 100,000 installed drives running spindle motors, KEB is the spindle drive leader.


If you want to know more, contact a KEB Applications Engineer today to find the right choice for your application.

Cost and performance balance in IIoT machine design

A Control Design reader asks

I work for an OEM, and we are developing new equipment that requires multiple motion applications on one machine. This includes master-follower rollers, tension control, unwind, wind, variable speed conveyors, a precision three-axis gantry and automatic changeover position adjustments. It covers the full range of motion control from simple ac induction motors to stepper motors and precision servo control.


Our sales department wants to sell this new OEM equipment as the latest technology including the buzzwords “precision motion” and “IoT-ready features.” With all the different motion-control requirements on the equipment, do I mix and match the best motor, stepper or servo for each axis, or do I just use servos on every axis? Along the same lines, should I stick with a single controller or distribute the motion control? I’m looking for best-practices in motion control for this new and future OEM equipment.


Engineering manager Scott Cunningham from KEB America was able to provide the reader with this answer.


There is a difference between what a sales department asks for and what it can sell. Machine designers and engineers are constantly tasked with the job of balancing cost with performance. Deciding to select all servos and the highest-performing control is often not the best choice.



C6 Smart Embedded Control

Regarding the controller, I would recommend using an embedded control or industrial PC (IPC) where you can. Create modular, brand-free code; use existing motion function blocks; and implement a synchronized motion fieldbus such as EtherCAT. Using an embedded subcontroller for the three-axis gantry would simplify your overall machine control, but distributing the controllers further may simply add cost to your machine.

Servos are not always the best choice in motor technology. AC motors and drives perform well where the rotor inertia doesn’t hinder performance, such as conveyors, master-followers and tension systems. Servos are typically the best performers on robots and high-speed gantry systems, where their high torque-to-inertia ratio really shines. However, if the gantry system is large, then servos lose their dynamic edge and ac motors meet the need. Small, subfractional hp applications can utilize stepper systems. In any case, choose a drive system that can be linked to the motion fieldbus. You will reduce machine wiring, ease motion control, improve machine troubleshooting, gain data collection and improve machine serviceability. Connected drives can be programmed automatically and are reachable via remote access.

Don’t forget remote access. Customers expect fast responses when something goes wrong. Using a secure, reliable remote device will pay for itself with the first trouble call.



You can read all the answers on Control Design’s web site where they regularly post Q & A articles like this one. If you’d like to hear more about our products and how they mesh with IIoT, click here to contact us today!

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