Application NotesTechnical Documentation & Guides

Overview

Copley drives use an I²T (I-squared-T) algorithm to keep a motor from overheating. It sums the heat a winding takes on from current over time, so it trips on sustained overcurrent but still passes the brief peak currents a motion profile needs. That's the balance a good overload limit has to strike: catch the damage, let the transients through.

Motor Heating Fundamentals

A winding dissipates heat as the square of its current (P = I²R). Run above the continuous rating long enough and that heat degrades insulation, demagnetizes the rotor magnets, or warps parts mechanically. The I²T algorithm models this heating so the drive can act before the motor gets there.

The I²T Algorithm

The I²T value is a running estimate of accumulated heat in the motor: the integral of current squared over time. The drive watches motor current and compares that running total against the motor's thermal capacity. Below the continuous rating, the value falls to model cooling. Above it, the value climbs.

User-Programmable Parameters

You set the protection parameters in CME 2:

• Continuous Current Rating (Ic) - The motor's rated continuous current
• Peak Current Limit (Ip) - Maximum allowable instantaneous current
• I²T Limit - The motor's thermal capacity rating
• Fault Action - Response when limit is reached (disable, fold-back, warning)

In-Limit Effect

As the I²T limit gets close, the drive can either hard-fault and disable the motor, or fold back the current limit gradually so the motor cools while it keeps running at reduced output. Fold-back is the better choice anywhere a hard stop would be worse than a slowdown.

Typical Applications

• High-duty-cycle servo applications
• Applications with frequent acceleration/deceleration
• Systems where motor thermal protection is critical
• Multi-axis systems with varying load profiles

Related Products

Xenus Plus • Accelnet • Stepnet • Nano Series

Overview

Copley drives speak CANopen using the DS402 (CiA 402) device profile for drives and motion. This note covers the parts you actually touch bringing one up: object dictionary access, PDO configuration, and the position, velocity, and torque modes.

CANopen Overview

CANopen is a higher-level protocol that runs on top of the CAN (Controller Area Network) physical layer. It defines standard objects for configuring devices, exchanging process data, and managing the network. Copley drives follow the DS402 profile, so they interoperate with other DS402 controllers.

Object Dictionary

Every CANopen parameter lives in the Object Dictionary, addressed by index and sub-index. Copley drives carry both the standard DS402 objects and manufacturer-specific ones for the extra features:

• Communication objects (0x1000-0x1FFF)
• Manufacturer-specific objects (0x2000-0x5FFF)
• Device profile objects (0x6000-0x9FFF)

Operating Modes

Copley CANopen drives support the DS402 operating modes:

• Profile Position Mode - Point-to-point positioning with trapezoidal profiles
• Profile Velocity Mode - Velocity control with acceleration limits
• Profile Torque Mode - Direct torque/current control
• Homing Mode - Reference point detection and setting
• Interpolated Position Mode - Synchronized multi-axis motion
• Cyclic Synchronous Position/Velocity/Torque (CSP, CSV, CST)

State Machine

DS402 defines a state machine the drive moves through: Not Ready to Switch On, Switch On Disabled, Ready to Switch On, Switched On, Operation Enabled, Quick Stop Active, and Fault. You drive the transitions by writing the Controlword object (0x6040).

Typical Applications

• Multi-axis coordinated motion
• PLC-based machine control
• Industrial automation systems
• Robotics applications

Related Products

Xenus Plus • Accelnet • Stepnet • Nano Series

Overview

CME 2 (Copley Motion Explorer 2) is the tool you use to configure and tune Copley drives. The setup runs in order: motor configuration, feedback, then the current, velocity, and position loops.

Initial Connection

CME 2 connects over RS-232, CANopen, or EtherCAT. It finds connected drives on its own and shows the current configuration. Before you change anything, read the drive's existing settings and save a backup — it's the fastest way back if a change goes wrong.

Motor Configuration

Get the motor parameters right or nothing downstream tunes well. The ones that matter:

• Motor type (brushless, brush, stepper)
• Pole count for brushless motors
• Continuous and peak current ratings
• Winding resistance and inductance
• Back-EMF constant (Ke)
• Torque constant (Kt)

Servo Loop Tuning

Copley drives use cascaded loops: current innermost, velocity in the middle, position outermost. Tune them in that order, inside out:

• Current Loop - Typically auto-tuned based on motor parameters
• Velocity Loop - Adjust Kp and Ki for desired bandwidth and stability
• Position Loop - Configure Kp, Kd, and Kff for accurate positioning

Auto-Tuning

CME 2 can auto-tune the gains for you. It injects test signals, watches how the system responds, and works out gain values from that. On demanding axes you'll usually still hand-tune from there.

Typical Applications

• Initial drive commissioning
• Motor replacement and reconfiguration
• Performance optimization
• Troubleshooting and diagnostics

Related Products

All Copley servo drives

Overview

A servo drive, or servo amplifier, takes a low-power command signal and turns it into the voltage and current a servo motor needs, holding position, velocity, and torque to tight tolerances. It sits between the motion controller and the motor, amplifying the command and closing the feedback loop so the motor actually does what it was told.

Basic Architecture

A drive has three parts: a power stage, a control stage built on a DSP or FPGA, and its communication interfaces. The power stage chops the DC bus into PWM output to the windings. The control stage runs the cascaded feedback loops fast enough to hold precision.

• Power stage: H-bridge or 3-phase inverter topology
• Control stage: DSP/FPGA running at 10-20 kHz loop rates
• Feedback interface: encoder, resolver, or absolute position sensor
• Communication: EtherCAT, CANopen, analog, or step/direction inputs

How Servo Drives Differ from VFDs

Both drive motors, but they aren't the same tool. A servo drive runs closed-loop on position feedback, so it can position accurately and respond fast. A VFD usually runs open-loop speed control on an induction motor. A servo drive instead gives you high-bandwidth control of a PMSM or brushless DC motor.

Choosing the Right Servo Drive

What to check when you're picking one:

• Motor type compatibility (brushless, brush, stepper, linear)
• Voltage and current ratings matching the motor
• Communication protocol requirements (EtherCAT, CANopen, etc.)
• Form factor (panel mount, PCB module, chip-level)
• Safety features (STO, SBC) if required

Typical Applications

• Industrial automation and robotics
• Semiconductor manufacturing
• Medical device positioning
• Packaging and printing machinery

Related Products

Xenus Plus • Accelnet Plus • Nano Series • Accelus

Overview

Grounding is one of the first things that goes wrong on a servo install and one of the last things people check. Get it wrong and you get noise pickup, ground loops, and intermittent faults that are miserable to chase. Here's how to wire the grounds so they don't bite you.

Ground Loop Prevention

A ground loop forms when two ground paths close a circuit that carries current you never intended. Between the drive, controller, and motor, that current couples into feedback signals and shows up as position errors or faults.

• Use a single-point (star) ground topology
• Connect all ground references to one common point
• Avoid daisy-chaining grounds between multiple drives
• Keep power ground and signal ground separated until the star point

Chassis Grounding

Bond every metal enclosure, DIN rail, and motor housing to protective earth (PE) with a low-impedance connection. Use flat braided strap, not round wire — braid has lower impedance at high frequency, which is where the noise lives. Scrape off paint or anodizing at the contact point so it's metal on metal.

Motor Cable Grounding

Run shielded motor cable and terminate the shield at both ends with a 360-degree clamp, not a pigtail. Land it on the drive's PE terminal and on the motor frame. Past about 25 meters, add ferrite cores at the drive end.

Typical Applications

• New servo system installations
• Troubleshooting noise-related faults
• Multi-axis cabinet design
• EMC compliance preparation

Related Products

All Copley servo drives

Overview

PWM switching makes a servo cabinet a noisy place, and your encoder feedback, command signals, and network traffic all have to stay clean through it. That comes down to which cable you run, how you route it, and how you terminate it.

Signal Cable Routing

Keep power and signal cable apart. Route encoder, communication, and analog command lines at least 200mm from motor power leads. Where they have to cross, cross at 90 degrees so they couple as little as possible.

• Maintain minimum 200mm separation between power and signal cables
• Route signal cables in separate cable trays or conduits
• Cross power cables at right angles only
• Keep signal cables as short as practical

Differential vs Single-Ended Signals

Differential signaling (RS-422, RS-485, differential encoders) shrugs off noise far better than single-ended. Copley drives take differential encoder inputs and differential analog commands. Use differential wherever you can, and definitely on long runs or in a noisy cabinet.

Encoder Cable Best Practices

Encoder cables are the touchy ones: a small distortion turns into a position error. Use shielded twisted-pair with an individual shield on each pair. Keep incremental encoder runs under 30 meters, and check the signal on CME 2's scope at the drive's own encoder inputs, not somewhere upstream.

Typical Applications

• Encoder signal troubleshooting
• Cabinet wiring design
• Long cable run installations
• EMI-sensitive environments

Related Products

Xenus Plus • Accelnet Plus • Stepnet

Overview

Shielding does two jobs: it keeps outside interference out of the drive and encoder, and it keeps the drive's own emissions from bothering the equipment around it. This last part of the series covers shield termination, cabinet EMC, and picking a line filter.

Cable Shield Termination

How you terminate the shield is often what separates a clean system from one that's full of noise. Best case is a 360-degree circumferential clamp, either an EMC gland or a shield clamp:

• Use EMC cable glands with 360° shield contact
• Never use pigtail shield connections—they act as antennas above 1 MHz
• Terminate shields at both cable ends for motor and encoder cables
• For communication cables (RS-232), ground shield at one end only to prevent ground loops

Cabinet EMC Design

Treat the control cabinet as a Faraday cage. Every panel joint needs continuous electrical contact, and cable entries should go through EMC glands. Mount the EMI filter right at the entry point and keep its leads short, so there's as little unfiltered cable inside the cabinet as possible.

EMI Filter Selection

Put a line filter on the AC input to meet conducted emissions limits. Size it for the total current of every drive in the cabinet, and check that it's rated for the drives' PWM switching frequency, usually 16-20 kHz.

Typical Applications

• CE marking compliance
• Machine EMC certification
• Sensitive measurement environments
• Co-located equipment installations

Related Products

Xenus Plus • Accelnet Plus • Stepnet

Overview

An I²T algorithm estimates motor heat. A sensor in the winding measures it. When you want the real temperature rather than a model, Copley drives can read a thermistor or RTD on an analog input and act on it before the motor is damaged.

Supported Temperature Sensors

Most servo motors ship with a temperature sensor embedded in the windings. Copley drives read:

• PTC Thermistors - Resistance increases sharply at trip temperature
• NTC Thermistors - Resistance decreases with temperature (10K NTC common)
• KTY84 Sensors - Linear silicon temperature sensors
• PT100/PT1000 RTDs - Precision platinum resistance sensors

Configuration in CME 2

Set this up on the analog input in CME 2. Switch the input mode to temperature sensor, pick the sensor type, and set a warning threshold and a fault threshold. The drive warns at the first and faults at the second.

Thermal Derating

As the temperature nears the warning threshold, the drive can pull the current limit down on its own, which cuts heating while the axis keeps running. In a lot of applications that slow fade beats dropping out on a hard fault.

Typical Applications

• High-ambient temperature environments
• Continuous-duty applications
• Motors without adequate cooling
• Safety-critical thermal monitoring

Related Products

Xenus Plus • Accelnet Plus • Accelnet

Overview

Plenty of machines need several axes moving in lockstep. Copley drives handle that a few ways, from plain master-follower gearing up to full cam profiles, timed by either EtherCAT Distributed Clocks or CANopen SYNC messages.

Electronic Gearing

Electronic gearing ties a follower axis to a master: the follower tracks master position times a gear ratio you set. Copley drives take integer and fractional ratios, and you can change the ratio on the fly.

• Gear ratio range: 1:1000 to 1000:1 with fractional support
• Master source: encoder input, another axis, or virtual master
• Smooth ratio transitions with configurable ramp time
• Phase offset adjustment for fine alignment

Electronic Camming

Electronic camming maps follower position to master position through any curve you define, doing the job of a mechanical cam without the hardware. Copley drives hold cam tables up to 3600 points and interpolate them with cubic splines, so the motion stays smooth at any speed.

EtherCAT Distributed Clocks

When you need the tightest sync, EtherCAT Distributed Clocks (DC) hold every axis on the network to under a microsecond of each other. Copley EtherCAT drives support the DC Sync0 and Sync1 signals, so all axes update on the same deterministic tick.

Typical Applications

• Flying shear and cut-to-length
• Printing and registration
• Coordinated robotic axes
• Conveyor tracking

Related Products

Xenus Plus • Accelnet Plus • M-Series

Overview

Functional safety is about getting the drive into a safe state the moment something dangerous happens, to protect the people and hardware around it. Copley Accelnet Plus drives do this through STO (Safe Torque Off) and SBC (Safe Brake Control), both certified to SIL 3 (IEC 61508) and PLe (ISO 13849).

Safe Torque Off (STO)

STO is the base safety function. It takes away the drive's ability to make torque by cutting the power stage through a redundant hardware path that doesn't depend on firmware. On Accelnet Plus, STO runs off dual-channel inputs:

• Dual-channel redundant input architecture
• Response time < 10ms from input activation to torque removal
• Hardware-based implementation independent of firmware
• Diagnostic coverage (DC) > 99% per IEC 61508
• Category 4 / PLe per ISO 13849-1

Safe Brake Control (SBC)

SBC works with STO to hold the brake on vertical or gravity-loaded axes so the load can't drop. When STO fires, SBC sets the brake before torque goes away, so nothing falls in the gap.

Safety System Integration

To bring STO into a machine's safety system, wire its inputs to a safety PLC or safety relay that's watching the E-stops, light curtains, and the rest. Design the whole circuit to hit the Performance Level (PL) or Safety Integrity Level (SIL) the application calls for.

Typical Applications

• Machine safeguarding per ISO 13849
• Vertical axis gravity protection
• Collaborative robot safety
• Emergency stop implementation

Related Products

Accelnet Plus (BEL, BPL, BE2, BP2)

Overview

STO stops the machine. Often the standards want something short of a full stop, so the machine can keep working in a restricted mode instead of dropping out. Copley drives offer a few functions for that, and each one still has to fit into the safety architecture without lowering the rating.

Safe Limited Speed (SLS)

SLS watches motor speed and trips STO if it goes past a safely-monitored limit. That lets someone work near the machine while it runs slowly, without giving up the safety rating. Copley's version uses dual-path speed monitoring, with the speed limit and response time both configurable.

• Configurable speed limit thresholds
• Selectable response: warning, speed reduction, or STO activation
• Monitoring via safety encoder feedback
• Compatible with reduced-speed maintenance modes

Safe Operating Stop (SOS)

SOS holds the motor stopped under active servo control and watches that position stays inside a safe window. Unlike STO, which removes torque, SOS keeps the motor energized and holding, which is exactly what a vertical axis needs, since cutting torque there would drop the load.

Safety Architecture Considerations

Once you stack several safety functions together, the whole architecture still has to hold the required SIL/PL. Account for common-cause failures across functions, diagnostic test intervals, and the proof-test schedule for checking the system over its life.

Typical Applications

• Maintenance mode operation
• Collaborative workspaces
• Vertical axis holding
• Safety-rated speed monitoring

Related Products

Accelnet Plus • Xenus Plus

Overview

The Copley Motion Library (CML) is a C/C++ library for driving Copley amplifiers from your own application. For robotics, it coordinates multiple axes deterministically through EtherCAT Cyclic Synchronous modes, and it hands you direct control of trajectory generation and the kinematics.

CML Architecture

CML wraps the drives in an object-oriented API, with classes for amplifiers, trajectories, I/O, and the network. It handles the low-level bus traffic so you can stay in application code:

• Amp class: Motor configuration, mode control, and status monitoring
• Trajectory classes: PVT, PT, and streaming position profiles
• LinkTrajectory: Coordinated multi-axis motion with blending
• Network class: EtherCAT and CANopen bus management
• Event system: Asynchronous status and fault notification

Real-Time Cyclic Synchronous Control

When a robot needs deterministic timing, CML supports EtherCAT Cyclic Synchronous Position (CSP) mode: your host code computes and sends a fresh position command every cycle, typically every 1-4 ms. That's where your own inverse kinematics, path planning, and force control run, on the PC.

Multi-Axis Coordination

CML's LinkTrajectory class runs synchronized multi-axis moves and profiles the velocity across all of them for you. Every axis starts, moves, and stops together no matter how far each one travels, which is what a Cartesian robot, SCARA arm, or gantry needs.

Typical Applications

• Custom robotic controllers
• Multi-axis gantry systems
• Pick-and-place machines
• Test and measurement automation

Related Products

Accelnet Plus • Xenus Plus • M-Series

Overview

MARCH Robotics picked Copley Accelnet Plus drives for their latest autonomous guided vehicles, the kind that move loads around warehouses and factories. The drive is small, runs EtherCAT, and works across the DC voltage range a battery pack actually sits in, which is what a mobile robot needs when it has to hold velocity accurately without wasting power.

Application Requirements

The MARCH AGV platform needed:

• Dual-wheel differential drive with independent velocity control
• 48VDC battery-powered operation with high efficiency
• EtherCAT connectivity to the onboard Linux-based controller
• Compact drive size to fit within the vehicle chassis
• Safe Torque Off (STO) for safety-rated stopping

Implementation

Two Accelnet Plus BEL drives run the left and right wheel motors in velocity mode over EtherCAT. The onboard navigation controller works out the differential wheel speeds from LIDAR and odometry and sends velocity commands at 1 kHz over Cyclic Synchronous Velocity (CSV) mode. The drives' own current limiting protects the motors when a wheel hits something or stalls.

Results

The drives navigated smoothly, holding velocity to better than 0.1% of the commanded speed. Battery life went up 15% over the previous drives, which came down to the Accelnet Plus power stage running more efficiently. STO gave them safety-rated Category 1 stops whenever the vehicle's safety scanner tripped.

Typical Applications

• Autonomous guided vehicles (AGVs)
• Mobile robots
• Battery-powered systems
• Warehouse automation

Related Products

Accelnet Plus (BEL, BPL)

Overview

Packaging machines lean on multi-axis motion: registration, synchronization, cam-based converting. Copley Motion Objects (CMO) are PLCopen-compliant function blocks for TwinCAT 3 and CODESYS, so a machine builder programs every Copley EtherCAT drive through one standard interface.

PLCopen Motion Function Blocks

CMO implements the standard PLCopen motion control function blocks:

• MC_Power - Enable/disable the drive
• MC_MoveAbsolute / MC_MoveRelative - Point-to-point positioning
• MC_MoveVelocity - Continuous velocity control
• MC_GearIn / MC_GearOut - Electronic gearing
• MC_CamIn / MC_CamOut - Electronic camming
• MC_Home - Homing with configurable methods

Packaging-Specific Features

On top of the standard PLCopen blocks, CMO adds packaging-specific ones: registration correction that nudges position from a sensor, flying shear profiles, and seal-bar synchronization. Having those prebuilt takes a job that used to run weeks down to hours.

Integration with TwinCAT 3

CMO drops into TwinCAT 3 as a standard library. Add the Copley ESI file, link the CMO library, and the drives show up as ordinary TwinCAT motion axes. Existing TwinCAT NC programs can run them without changes.

Typical Applications

• Form-fill-seal machines
• Cartoning and case packing
• Label application
• Conveyor synchronization

Related Products

Xenus Plus • Accelnet Plus • Stepnet

Overview

EtherCAT (Ethernet for Control Automation Technology) is the fastest of the industrial Ethernet protocols for motion, with sub-microsecond synchronization and multi-axis cycle times under 1 ms. This note runs from the hardware wiring through commissioning a Copley drive on the network.

Network Topology

EtherCAT runs as a daisy chain, where each slave reads and writes its data as the frame passes through it. Copley drives have two RJ-45 ports for that:

• Connect master to first drive Port In, first drive Port Out to second drive Port In, etc.
• Maximum 65,535 slaves per segment (typically limited by cycle time requirements)
• Cable length up to 100m between devices (standard Ethernet Cat5e/Cat6)
• Ring topology supported for redundancy when master supports it

ESI File Installation

The EtherCAT Slave Information (ESI) file tells the master what the drive can do. Grab the current Copley ESI file from copleycontrols.com and load it into your master's config tool, whether that's TwinCAT, CODESYS, or Acontis. It defines the available PDO mappings, the supported modes, and the drive parameters.

PDO Mapping Configuration

Process Data Objects (PDOs) are the data that moves every cycle. Copley drives let you configure both the RxPDO (master→drive) and the TxPDO (drive→master). The standard DS402 mappings come preconfigured, and you can build custom ones when an application needs them:

• Standard mapping: Controlword, Target Position, Statusword, Actual Position
• Add velocity, torque, or I/O data as needed
• Maximum PDO size depends on drive model
• Configure via SDO during Pre-Operational state

Distributed Clocks

EtherCAT Distributed Clocks (DC) lock every drive to one time base to within a microsecond. Turn on DC Sync0 for the synchronized cyclic modes (CSP, CSV, CST). During startup the master measures the propagation delay to each slave and trims its clock to match.

Typical Applications

• Multi-axis EtherCAT systems
• High-speed synchronized motion
• TwinCAT and CODESYS integration
• New EtherCAT network commissioning

Related Products

Xenus Plus • Accelnet Plus • M-Series • Stepnet (STX)