Copley Controls Accelnet Plus BEL Series User manual

Accelnet & Stepnet
Plus Panels
User Guide
16-01339
Revision 07
September 16, 2021

Accelnet & Stepnet Plus Panels User Guide 16-01339 Rev 07
Contents
1About This Manual...........................................................................................................................................................................4
1.1 Title, Number, Revision............................................................................................................................................................4
1.2 Revision History.......................................................................................................................................................................4
1.3 Overview and Scope................................................................................................................................................................4
1.4 Original Instructions.................................................................................................................................................................4
1.5 Related Documentation ...........................................................................................................................................................4
1.6 EC Declaration of Conformity –Contents................................................................................................................................5
1.6.1 EC Declaration of Conformity for Accelnet Plus BE2 BP2.......................................................................................5
1.6.2 EC Declaration of Conformity for Accelnet Plus BEL BPL.......................................................................................6
1.6.3 EC Declaration of Conformity for Stepnet Plus TE2 TP2.........................................................................................7
1.6.4 EC Declaration of Conformity for Stepnet Plus TEL TPL.........................................................................................8
1.7 Comments................................................................................................................................................................................9
1.8 Copyrights................................................................................................................................................................................9
1.9 Document Validity....................................................................................................................................................................9
1.10 Product Warnings..................................................................................................................................................................9
2Introduction....................................................................................................................................................................................11
2.1 Accelnet & Stepnet Plus Panels Overview ............................................................................................................................11
2.2 Accelnet Plus Panel Models ..................................................................................................................................................12
2.3Stepnet Plus Panel Models....................................................................................................................................................12
2.4 CME.......................................................................................................................................................................................13
2.5 CVM (Copley Virtual Machine, Indexer 2)..............................................................................................................................13
2.6 CMO (Copley Motion Objects)...............................................................................................................................................13
2.7 CML (Copley Motion Libraries) ..............................................................................................................................................13
2.8 CPL (Copley Programming Language)..................................................................................................................................13
3Operational Theory........................................................................................................................................................................14
3.1 Drive Input Power ..................................................................................................................................................................14
3.2 Commutation Modes..............................................................................................................................................................15
3.3 Feedback...............................................................................................................................................................................15
3.4 Operating Modes ...................................................................................................................................................................16
Current Loop Inputs...............................................................................................................................................................18
Velocity Mode and Velocity Loop...........................................................................................................................................19
Position Mode and Position Loop ..........................................................................................................................................22
3.5 Input Command Types...........................................................................................................................................................24
3.6 Communications....................................................................................................................................................................29
3.7 Limit Switches........................................................................................................................................................................34
3.8 Brake Operation.....................................................................................................................................................................35
3.9 Protection...............................................................................................................................................................................37
3.10 Position and Velocity Errors.................................................................................................................................................39
3.11 Digital Inputs BEL,BPL, BML,TEL ......................................................................................................................................41
Digital Inputs..........................................................................................................................................................................41
Analog Inputs.........................................................................................................................................................................41
3.12 Inputs: BE2, BP2, TE2, TP2................................................................................................................................................41
Analog Inputs.........................................................................................................................................................................42
3.13 Outputs: BEL, BPL, BML, TEL.............................................................................................................................................42
3.14 Outputs: BE2, BP2, TE2 and TP2 .......................................................................................................................................42
4Specifications.................................................................................................................................................................................43
4.1 DC Input Power......................................................................................................................................................................43
Single-Axis Servo Models: BEL, BPL, BML...........................................................................................................................43
Dual-Axis Servo Models: BE2, BP2.......................................................................................................................................43
Single-Axis Stepper Model: TEL............................................................................................................................................44
Dual-Axis Stepper Models: TE2, TP2 ....................................................................................................................................44
4.2 Power Output.........................................................................................................................................................................45
Single-Axis Servo Models: BEL, BPL, BML...........................................................................................................................45
Dual-Axis Servo Models: BE2, BP2.......................................................................................................................................45
Single-Axis Stepper Model: TEL............................................................................................................................................46
Dual-Axis Stepper Models: TE2, TP2 ....................................................................................................................................46
4.3 Control Loops.........................................................................................................................................................................47
4.4 Digital Command Input ..........................................................................................................................................................47
4.5 Analog Inputs.........................................................................................................................................................................48
BEL, BPL, BML, TEL .............................................................................................................................................................48
BE2, BP2, TE2, TP2..............................................................................................................................................................48
4.6 Digital Inputs..........................................................................................................................................................................49
BEL, BPL, BML, TEL .............................................................................................................................................................49
BE2, BP2, TE2, TP2..............................................................................................................................................................49
4.7 Digital Outputs .......................................................................................................................................................................50
BEL, BPL, BML, TEL .............................................................................................................................................................50
BE2, BP2, TE2, TP2..............................................................................................................................................................50

Accelnet & Stepnet Plus Panels User Guide 16-01339 Rev 07
4.8 Encoder +5V Power Output...................................................................................................................................................51
BEL, BPL, BML, TEL .............................................................................................................................................................51
BE2, BP2, TE2, TP2..............................................................................................................................................................51
4.9 Primary Encoder Inputs .........................................................................................................................................................51
Digital Encoders.....................................................................................................................................................................51
Analog (Sin/Cos) Incremental Encoders................................................................................................................................52
4.10 Digital Hall Sensor Inputs ....................................................................................................................................................52
BEL, BPL, BML, BE2, BP2 ....................................................................................................................................................52
4.11 Resolver Feedback..............................................................................................................................................................53
BEL, BPL, BE2, BP2..............................................................................................................................................................53
4.12 Multi-Mode Port ...................................................................................................................................................................53
4.13 Serial Interface.....................................................................................................................................................................54
4.14 Network Interfaces...............................................................................................................................................................55
4.15 Status Indicators..................................................................................................................................................................56
Drive Status Indicator.............................................................................................................................................................56
Network Status Indicators......................................................................................................................................................57
4.16 Fault Levels .........................................................................................................................................................................58
4.17 Operating Temperature and Cooling Configurations...........................................................................................................58
4.18 Mechanical and Environmental............................................................................................................................................63
4.19 Agency Standards & Conformance .....................................................................................................................................65
4.20 Dimensions..........................................................................................................................................................................66
5Wiring & Connections....................................................................................................................................................................68
5.1 Electrical Codes and Warnings..............................................................................................................................................68
5.2 Grounding Considerations .....................................................................................................................................................69
5.3 Connector Locations..............................................................................................................................................................73
5.4 Power Connector Locations –Accelnet Models ....................................................................................................................75
BEL, BPL, BE2, BP2 - Motor Connectors..............................................................................................................................76
5.5 Power Connector Locations –Stepnet Models......................................................................................................................77
5.6 TEL, TE2, TP2 Motor Connectors..........................................................................................................................................78
5.7 Motor Brake Connector..........................................................................................................................................................79
BEL, BPL, BML,TEL BE2, BP2, TE2, TP2.........................................................................................................................80
5.8 Safe Torque Off .....................................................................................................................................................................81
5.9 RS-232 Serial Communications.............................................................................................................................................83
5.10 Network Ports......................................................................................................................................................................84
EtherCAT: BEL, BE2, TEL, TE2 ...........................................................................................................................................84
5.11 Control I/O ...........................................................................................................................................................................86
5.11.1 Multi-Mode Port......................................................................................................................................................97
5.12 Motor Feedback.................................................................................................................................................................102
6Appendix.......................................................................................................................................................................................108
A: I2T Time Limit Algorithm.......................................................................................................................................................108
B: Connecting BPL/BP2/TP2 for Serial Control........................................................................................................................110
C: Ordering Guide and Accessories.........................................................................................................................................111

Accelnet & Stepnet Plus Panels User Guide 16-01339 Rev 07
1 ABOUT THIS MANUAL
1.1 TITLE,NUMBER,REVISION
Title
Accelnet & Stepnet Plus Panels User Guide
Document Number
16-01339
Current Revision
07
1.2 REVISION HISTORY
Revision
Date
ECO
Comments
AA
December 30, 2014
ECO-056909
Originated from 16-01169 Rev 00
00
March 23, 2015
ECO-057405
Updated PE and grounding graphics
01
February 23, 2017
ECO-065615
Add BML models
02
March 21, 2017
ECO-066296
Update to reflect EN 61800-5-2:2007
03
April 18, 2018
ECO-069980
Changed the analog input pin 3 to pin 34
04
June 27, 2019
ECO-073565
Pin out typos for the Power Pins fixed
05
October 22, 2020
ECO-077762
Update to reflect IEC 61800-5-2:2016
06
December 8, 2020
ECO-078133
Update to reflect latest edition of IEC 61800-3
and IEC 61800-5-1
07
September 16, 2021
ECO-080110
Update to relfect changes to front panel brake
signals
1.3 OVERVIEW AND SCOPE
This manual describes the operation and installation of the Accelnet BEL, BE2, BPL, BP2, BML
and Stepnet TEL, TE2 and TP2 drives manufactured by Copley Controls.
All Accelnet and Stepnet Plus Panel products have serial numbers that incorporate the week and year of
production into the first 4 digits (WWYY) of the serial number.
1.4 ORIGINAL INSTRUCTIONS
This manual is considered to be “original instructions” as defined in EC Directive 2006/42/EC and the contents
have been verified by Copley Controls.
1.5 RELATED DOCUMENTATION
For important setup and operation information, see the CME User Guide (www.copleycontrols.com)
Users of the CANopen features should also read these Copley Controls documents:
CANopen Programmer’s Manual
CMO (Copley Motion Objects) Programmer’s Guide
CML Reference Manual (License required)
MACRO Network User Guide
Also of related interest:
Indexer 2 Program User’s Guide (describes use of Indexer Program to create motion control sequences)
ASCII Programmer’s Guide (describes how to send ASCII format commands over a drive’s serial bus to set
up and control one or more drives)
Copley Amplifier Parameter Dictionary

Accelnet & Stepnet Plus Panels User Guide 16-01339 Rev 07
Copley Camming User Guide
Copley Controls Serial Encoder Guide
CPL User Guide (License required)
Accelnet & Stepnet Plus Panels STO Manual
Links to these publications, along with other documents, data sheets and software releases,
can be found at www.copleycontrols.com.
1.6 EC DECLARATION OF CONFORMITY –CONTENTS
1.6.1 EC DECLARATION OF CONFORMITY FOR ACCELNET PLUS BE2 BP2

Accelnet & Stepnet Plus Panels User Guide 16-01339 Rev 07
1.6.2 EC DECLARATION OF CONFORMITY FOR ACCELNET PLUS BEL BPL

Accelnet & Stepnet Plus Panels User Guide 16-01339 Rev 07
1.6.3 EC DECLARATION OF CONFORMITY FOR STEPNET PLUS TE2 TP2

Accelnet & Stepnet Plus Panels User Guide 16-01339 Rev 07
1.6.4 EC DECLARATION OF CONFORMITY FOR STEPNET PLUS TEL TPL

Accelnet & Stepnet Plus Panels User Guide 16-01339 Rev 07
1.7 COMMENTS
Copley Controls welcomes your comments on this manual.
For contact information, see www.copleycontrols.com.
1.8 COPYRIGHTS
No part of this document may be reproduced in any form or by any means, electronic or mechanical, including
photocopying, without express written permission of Copley Controls.
Accelnet BEL, BE2, BPL, BP2, BML and Stepnet TEL, TE2, and TP2 are registered trademarks
of Copley Controls.
CME is a registered trademark of Copley Controls.
Windows XP, Windows 7, Visual Basic, and .NET are trademarks or registered trademarks
of Microsoft Corporation.
LabVIEW is a registered trademark of National Instruments.
EtherCAT is a registered trademark and patented technology, licensed by
Beckhoff Automation GmbH, Germany.
1.9 DOCUMENT VALIDITY
We reserve the right to modify our products. The information in this document is subject to change without
notice and does not represent a commitment by Copley Controls.
Copley Controls assumes no responsibility for any errors that may appear in this document.
1.10 PRODUCT WARNINGS
GENERAL
Observe all relevant state, regional and local safety regulations when installing and using this product. Be sure
that all wiring complies with the National Electrical Code (NEC) or its national equivalent, and all prevailing
local codes.
There are no user serviceable parts in the Accelnet or Stepnet Plus Panel servo drives. Removal of the cover
or tampering with internal components will void the warranty.
DANGER
DANGER: HAZARDOUS VOLTAGES.
Exercise caution when installing and adjusting. Persons responsible for installing and commissioning Accelnet Plus
servo drives and Stepnet Plus stepper drives must be experienced in all aspects of electrical equipment installations.
FAILURE TO HEED THIS WARNING CAN CAUSE EQUIPMENT DAMAGE, INJURY, OR DEATH.
DANGER
RISK OF ELECTRIC SHOCK.
DC Supplies used to power Accelnet and Stepnet Plus Panel drives must be transformer-isolated and provide
reinforced insulation from AC mains power.
FAILURE TO HEED THIS WARNING CAN CAUSE EQUIPMENT DAMAGE, INJURY, OR DEATH.
DANGER
RISK OF UNEXPECTED MOTION WITH NON-LATCHED FAULTS.
After the cause of a non-latched fault is corrected, the drive re-enables the PWM output stage without operator
intervention. In this case, motion may re-start unexpectedly. Configure faults as latched unless a specific situation
calls for non-latched behavior. When using non-latched faults, be sure to safeguard against unexpected motion.
FAILURE TO HEED THIS WARNING CAN CAUSE EQUIPMENT DAMAGE, INJURY, OR DEATH.
DANGER
USING CME OR SERIAL COMMANDS MAY AFFECT OR SUSPEND CAN OR ETHERCAT OPERATIONS.
When operating the drive as a CAN or EtherCAT node over a network, the use of CME or ASCII serial commands
may affect network operations in progress. Using such commands to initiate motion may cause network operations to
suspend. Network operations may restart unexpectedly when the commanded motion is stopped.
FAILURE TO HEED THIS WARNING CAN CAUSE EQUIPMENT DAMAGE, INJURY, OR DEATH.
!
!
!
!

Accelnet & Stepnet Plus Panels User Guide 16-01339 Rev 07
DANGER
LATCHING AN OUTPUT DOES NOT ELIMINATE THE RISK OF UNEXPECTED MOTION
WITH NON-LATCHED FAULTS.
Associating a fault with a latched, custom-configured output does not latch the fault itself. After the cause of a non-
latched fault is corrected, the drive re-enables without operator intervention. In this case, motion may re-start
unexpectedly.
FAILURE TO HEED THIS WARNING CAN CAUSE EQUIPMENT DAMAGE, INJURY, OR DEATH.
DANGER
USE EQUIPMENT AS DESCRIBED.
Operate drives within the specifications provided in this manual.
FAILURE TO HEED THIS WARNING CAN CAUSE EQUIPMENT DAMAGE, INJURY, OR DEATH.
DANGER
REFER TO THE ACCELNET & STEPNET PLUS PANELS STO MANUAL
The information provided in the Accelnet & Stepnet Plus Panels STO Manual must be considered
for any application using the STO feature.
FAILURE TO HEED THIS WARNING CAN CAUSE EQUIPMENT DAMAGE, INJURY, OR DEATH.
WARNING
DO NOT PLUG OR UNPLUG CONNECTORS WITH POWER APPLIED.
The connecting or disconnecting of cables while the drive has HVAUX and/or HV DC power applied is
not recommended.
FAILURE TO HEED THIS WARNING MAY CAUSE EQUIPMENT DAMAGE.
!
!
!
!

Accelnet & Stepnet Plus Panels User Guide 16-01339 Rev 07
2 INTRODUCTION
2.1 ACCELNET &STEPNET PLUS PANELS OVERVIEW
This table shows the model families and characteristics:
Axes
EtherCAT
CANopen
MACRO
Motor
Accelnet
1
BEL
BPL
BML
Servo
2
BE2
BP2
-
Stepnet
1
TEL
-
-
Stepper
2
TE2
TP2
-
All of these drives provide 100% digital control of brushless, brush, or stepper motors in DC powered panel
packages. Accelnet Plus models drive servo motors and Stepnet Plus drives are for stepper motors.
All of these Plus Panel models provide a Safe Torque Off (STO) function. Two opto-couplers are provided
which, when de-energized, prevent the upper and lower devices in the PWM outputs from being operated by
the digital control core. This provides a positive OFF capability that cannot be overridden by the control
firmware, or associated hardware components. When the opto-couplers are energized (current is flowing
through the input diodes), the control core will be able to control the on/off state of the PWM outputs. For more
information on STO for the Accelnet & Stepnet Plus Dual Axis models, see the Accelnet & Stepnet Plus Panel
STO Manual.
Accelnet Plus models support a wide range of feedback devices. The standard versions support digital
quadrature encoders, analog sin/cos encoders, and EnDat, BiSS, SSI, and Absolute A encoders. The -R
versions support brushless resolvers. The standard and -R versions can emulate a digital quadrature encoder
output from the analog encoder or resolver respectively.
Accelnet & Stepnet Plus Panels models can operate in several basic ways:
•Accelnet Plus Panel drives accept current, velocity or position commands from an external controller.
In current and velocity modes they can accept ±10 Vdc analog, digital 50% PWM or PWM/polarity
inputs. In position mode, inputs can be incremental position commands from step-motor controllers in
Pulse and Direction or Count Up/Count Down format, as well as A/B quadrature commands from a
master-encoder. Pulse-to-position ratio is programmable for electronic gearing.
•Stepnet Plus Panel drives typically accept position commands from an external controller as Pulse
and Direction or Count Up/Count Down format, as well as A/B quadrature commands from a master-
encoder. Pulse-to-position ratio is programmable for electronic gearing. Stepper motors with encoders
can be operated in servo mode providing position, velocity, or torque control.
•CANopen models can be nodes on a CANopen network. CANopen compliance allows the drive to
take instruction from a master application to perform torque, velocity, and position profiling,
interpolated position, and homing operations. Multiple drives can be tightly synchronized for high
performance coordinated motion.
•EtherCAT models operate as slave devices on the network. Servo drives can perform the CANopen
operating modes with the additional cyclic-synchronous position, velocity, and torque modes.
•MACRO models can be nodes on a MACRO network.
•All models can work as stand-alone controllers running CVM control programs such as the Indexer 2
Program. Or they can be controlled directly over an RS-232 serial link with simple ASCII format
commands.

Accelnet & Stepnet Plus Panels User Guide 16-01339 Rev 07
2.2 ACCELNET PLUS PANEL MODELS
Network
Axes
Models
Ic
Ip
Vdc
EtherCAT
1-Axis
BEL-090-06
3
6
14~90
BEL-090-14
7
14
BEL-090-30
15
30
2-Axis
BE2-090-06
3
6
BE2-090-14
7
14
BE2-090-20
10
20
CANopen
1-Axis
BPL-090-06
3
6
BPL-090-14
7
14
BPL-090-30
15
30
2-Axis
BP2-090-06
3
6
BP2-090-14
7
14
BP2-090-20
10
20
MACRO
1-Axis
BML-090-06
3
6
BML-090-14
7
14
BML-090-30
15
30
Ic = Continuous Output Current, Adc (peak of sine)
Ip = Peak Output Current, Adc (peak of sine)
Vdc = HV power supply voltage (DC, line-isolated)
The models listed above are available with the following options added to the part number:
-R: Resolver feedback (Example BEL-090-14-R). Resolver feedback not available on BML models.
-H: Factory-installed heatsink (Example: BEL-090-14-H)
-R-H: Resolver option with factory-installed heatsink (Example: BEL-090-14-R-H)
2.3 STEPNET PLUS PANEL MODELS
Network
Axes
Models
Ic
Ip
Vdc
EtherCAT
1-Axis
TEL-090-07
5
7
14~90
TEL-090-10
10
10
2-Axis
TE2-090-07
5
7
TE2-090-10
10
10
CANopen
2-Axis
TP2-090-07
5
7
TP2-090-10
10
10
Ic = Continuous Current, Adc (peak of sine)
Ip = Peak Current, Adc (peak of sine)
Vdc = HV power supply voltage (DC, line-isolated)
The models listed above are available with the following option added to the part number:
-H: Factory-installed heatsink (Example: TEL-090-10-H)

Accelnet & Stepnet Plus Panels User Guide 16-01339 Rev 07
2.4 CME
Drive commissioning is fast and simple using Copley Controls CME software. CME communicates with
Accelnet & Stepnet via an RS-232, CANopen, or EtherCAT link, and all of the operations needed to configure
the drive are accessible through CME.
The serial multi-drop feature allows CME to use a single RS-232 serial connection to one drive as a gateway
to other drives linked together by CAN bus connections.
Auto phasing of brushless motor Hall sensors and phase wires eliminates “wire and try.” Connections are made
once and CME does the rest. Encoder or resolver wire swapping to establish the direction of positive motion
is also eliminated.
Drive data can be saved & restored in a number of file types with the following file type extensions:
•CCM Motor, encoder, and brake settings
•CCX Drive configuration and settings
•CCP Indexer 2 (CVM, Copley Virtual Machine) programs
•CCT Cam tables
•CCG Gain-scheduling tables
•CCD Drive settings
2.5 CVM (COPLEY VIRTUAL MACHINE,INDEXER 2)
CVM is an embedded virtual programmable controller used to download Copley’s Indexer 2 programs to
Copley drives. It is accessed via CME and can be opened from CME’s main window.
2.6 CMO (COPLEY MOTION OBJECTS)
Copley Motion Objects (CMO) makes CANopen or EtherCAT network commissioning fast and simple. All
network housekeeping is taken care of automatically by a few simple commands linked into your application
program. CMO provides a suite of .NET objects that can be used by Visual Basic, LabVIEW, or any other
program supporting the Microsoft .NET object interface.
2.7 CML (COPLEY MOTION LIBRARIES)
CML provides a suite of C++ source code, allowing a C++ application program to communicate with and control
a drive over the CANopen or EtherCAT network.
2.8 CPL (COPLEY PROGRAMMING LANGUAGE)
CPL is Copley’s high level programming language for writing custom CVM programs. It expands on CVM’s
Indexer 2 capabilities with interrupts and features that are faster and more flexible, including looping and
branching capabilities.

Accelnet & Stepnet Plus Panels User Guide 16-01339 Rev 07
3 OPERATIONAL THEORY
3.1 DRIVE INPUT POWER
Power distribution within Accelnet& Stepnet Plus Panels has a common ground which is isolated fromthe heatplate.
The CANopen, EtherCAT and MACRO network signals are isolated from all of the drive circuits.
LOGIC/SIGNAL POWER
An internal DC/DC converter operates from the either the +HV or Aux inputs and creates the required
logic/signal operating voltages. Deriving internal operating voltages from the Aux input enables the drive to
stay on-line when the +HV power has been disconnected for emergency-stop or operator-intervention
conditions. This allows network and serial communications to remain active so that the drive can be monitored
by the control system while the +HV power is removed.
+HV POWER
The +HV input drives the high-voltage PWM outputs. When this is used without the Aux power, all of the drive
control and PWM output power is derived from the +HV power.
AUX POWER
The Aux input only drives the DC/DC converter and is diode-isolated from the PWM outputs. It has the same
voltage range as the +HV power and is recommended when the drives are in a network. The control core,
feedback devices, and network connections are all maintained by the Aux power so that the system controller
has visibility of the drive status, motor position, I/O states, etc. while the +HV is removed for safety,
loading/unloading work stations, etc.
PWM SWITCHING FREQUENCY SYNCHRONIZING
In some situations, such as when sampling small analog signals, it is desirable to synchronize the PWM
switching frequency among multiple drives. In these cases, one drive serves as a master for one or more slave
drives. The PWM sync output of the master sends a signal that is received as a PWM sync input by each slave.

Accelnet & Stepnet Plus Panels User Guide 16-01339 Rev 07
Using EtherCAT, the distributed clock feature can be used to establish PWM switching frequency synchronization
among the network connected drives. Typically one drive acts as the Sync 0 message producer. The master then
adjusts the Sync 0 frequency and phase in the slaves to so that they are all in-sync.
Over CANopen, one drive produces a Sync message that carries a high-resolution time-stamp. The other
drives on the network receive the Sync message and adjust their internal clocks so that all of the drives on the
network have their PWM frequencies synchronized.
In a MACRO ring, the master frequency must be a multiple of the drive’s current loop frequency.
When this is done the PWM frequencies of all the drives will be synchronized.
3.2 COMMUTATION MODES
The servo drive models (Bxx) support three commutation modes to drive brush and brushless motors:
AC brushless sinusoidal, DC brushless trapezoidal, and DC brush.
In most applications, sinusoidal commutation is preferred over trapezoidal, because it reduces torque ripple
and offers the smoothest motion at any velocity or torque. In the sinusoidal commutation mode, an encoder or
resolver is required for brushless sinusoidal commutation. Halls are sufficient for trapezoidal commutation.
When driving a DC brush motor, the drive operates as a traditional H-Bridge drive. No feedback is required for
torque (current) control but is needed for velocity or position control.
Stepper drives in microstepping mode have no need for commutation because the motor rotor is always
following the current vector created by the master. If operating in servo-mode, Stepnet drives use the encoder
feedback to auto-phase when the drive is enabled (wake-and-shake, or wake-and-wiggle).
3.3 FEEDBACK
ENCODER AND RESOLVER SUPPORT
The standard versions of the Accelnet & Stepnet Plus Panel drives support digital quadrature encoders, analog
sin/cos encoders, and a variety of absolute encoder formats. These versions normally require the use of Hall
switches for the commutation of brushless motors when incremental encoders are used. Absolute encoders
provide position and commutation feedback thus Halls are not required.
The resolver versions, designated by “–R” in the model number, support standard, single speed, resolvers.
Resolvers provide absolute position feedback of the motor rotor and are sufficient for commutation as well as
high-resolution motor rotor position reporting.
DC brush motors are self-commutating and only require feedback that reports the rotor position in either
absolute or incremental format.
MULTI-MODE PORT
The multi-mode port on the control connector can be configured for various functions, depending on type of
drive.
•Output buffered digital encoder A/B/X signals from a digital incremental motor encoder.
•Output emulated digital A/B encoder signals derived from analog sin/cos encoder or resolver.
•Output emulated digital A/B encoder signals from an absolute encoder
•Input a secondary digital encoder to be used in the dual encoder position mode. In this mode, an encoder
attached to the load provides position loop feedback, and the motorencoder or resolver provides velocity
loop feedback.

Accelnet & Stepnet Plus Panels User Guide 16-01339 Rev 07
3.4 OPERATING MODES
MODES AND CONTROL LOOPS
NESTING OF CONTROL LOOPS AND MODES
Copley Controls Accelnet & Stepnet Plus Panel servo drives use up to three nested control loops, current,
velocity, and position, to control a motor in three associated operating modes. Plus Panel stepper drives
typically operate in microstepping mode which is a form of open-loop position and velocity control. When
stepper motors are equipped with encoders, they can operate stepper motors as brushless servo motors that
use the same nested control loops as the servo drives.
This graphic shows the three control loops in a Plus Panel drive. The innermost loop controls current. This
loop becomes an element in the velocity loop. Finally, the position loop takes the command input from a
position commanding source which could be analog inputs, digital inputs, or commands over a network such
as EtherCAT or CANopen.

Accelnet & Stepnet Plus Panels User Guide 16-01339 Rev 07
BASIC ATTRIBUTES OF ALL CONTROL LOOPS
Control loops (and servo control loops in general) share several common attributes:
Loop Attribute
Description
Command input
Every loop is given a value to which it will attempt to control. For example, the velocity
loop receives a velocity command that is the desired motor speed.
Limits
Limits are set on each loop to protect the motor and/or mechanical system.
Feedback
The nature of servo control loops is that they receive feedback from the device they are
controlling. For example, the position loop uses the actual motor position as feedback.
Gains
These are constant values that are used in the mathematical equation of the servo
loop. The values of these gains can be adjusted during drive setup to improve the loop
performance. Adjusting these values is often referred to as tuning the loop.
Output
The loop generates a control signal. This signal can be used as the command signal to
another control loop or the input to a power drive.

Accelnet & Stepnet Plus Panels User Guide 16-01339 Rev 07
CURRENT MODE AND CURRENT LOOP
CURRENT LOOP DIAGRAM
As shown below, the “front end” of the current loop has filters and a limiting stage. The limiting stage accepts
a current command, applies limits, and passes a limited current command to the summing junction. The
summing junction subtracts the actual current (represented by the feedback signal) from the limited current
and produces an error signal. This error signal is then processed using the integral and proportional gains to
produce a voltage-control command which is applied to the drive’s PWM power outputs.
CURRENT LOOP INPUTS
Current commands can come from these sources:
•Analog or digital PWM inputs.
•A CANopen, MACRO or EtherCAT network, or RS-232 command.
•A CVM indexer program.
•CMO, CML, or CPL program commands.
•The drive’s internal function generator.
•In velocity or position modes, the current command is generated by the velocity loop.
OFFSET
The current loop offset is intended for use in applications where there is a constant force applied to, or required
of, the servomotor and the system must control this force. Typical applications would be a vertical axis holding
against gravity, or web tensioning. This offset value is summed with the current command before the limiting
stage.
LIMITS
The current command is limited based on the following parameters:
Limiter
Description
Peak Current
Limit
Maximum current that can be generated by the drive for a short duration of time. This value
cannot exceed the peak current rating of the drive.
Continuous
Current Limit
Maximum current that can be constantly generated by the drive cannot exceed the continuous
current rating of the drive.
I2T Time Limit
Maximum amount of time that the peak current can be applied to the motor before it must be
reduced to the continuous limit or generate a fault.
For more details, see I2T Time Limit Algorithm.
Note: Although the current limits set by the user may exceed the drive's internal limits, the drive
operates using both sets of limits in parallel, and therefore will not exceed its own internal limits
regardless of the values programmed.
Ramp
Rate of change in current command.

Accelnet & Stepnet Plus Panels User Guide 16-01339 Rev 07
CURRENT LOOP GAINS
The current loop uses these gains:
Gain
Description
Cp - Current loop proportional
The current error (the difference between the actual and the limited
commanded current) is multiplied by this value. The primary effect of this
gain is to increase bandwidth (or decrease the step-response time) as the
gain is increased.
Ci - Current loop integral
The integral of the current error is multiplied by this value. Integral gain
reduces the current error to zero over time. It controls the DC accuracy of
the loop, or the flatness of the top of a square wave signal. The error
integral is the accumulated sum of the current error value over time.
CURRENT LOOP OUTPUT
The output of the current loop is a command that sets the duty cycle of the PWM output stage of the drive.
This provides a variable voltage-source.
AUTO TUNE
CME provides a current loop Auto Tune feature, which automatically determines optimal Cp and Ci values for
the motor. For more information, see the CME User Guide.
VELOCITY MODE AND VELOCITY LOOP
VELOCITY LOOP DIAGRAM
As shown below, the velocity loop limiting stage accepts a velocity command, applies limits, and passes a
limited velocity command to the command filter. The output of the filter is a velocity command to the summing
junction. The summing junction subtracts the actual velocity derived from the feedback device (encoder,
resolver), and produces a velocity error signal. The velocity loop feedback signal is always from the motor
feedback device even when an additional encoder is attached to the load. The velocity error is then processed
using the integral and proportional gains which is added to a feedforward signal to produce the commanded
current. Programmable digital filters are provided on the input of the velocity loop, following the limiting stage,
and on the output of the velocity loop that will become the commanded current which controls the current loop.

Accelnet & Stepnet Plus Panels User Guide 16-01339 Rev 07
VELOCITY LOOP INPUTS
In velocity mode, the Commanded Velocity command comes from one of the following sources:
•Analog or digital PWM inputs
•A network command, CAN, or RS-232 Serial.
•A CVM indexer control program.
•CMO, CML, or CPL program commands.
•The drive’s internal function generator.
•In position mode, the velocity command is generated by the position loop error.
VELOCITY LOOP LIMITS
The velocity command is limited based on the following set of parameters designed to protect the motor and/or
the mechanical system.
Limiter
Description
Velocity Limit
Sets the maximum velocity command input to the velocity loop.
Acceleration Limit
Limits the maximum acceleration rate of the commanded velocity input to the
velocity loop. This limit is used in velocity mode only.
Deceleration Limit
Limits the maximum deceleration rate of the commanded velocity input to the
velocity loop. This limit is used in velocity mode only.
Fast Stop Ramp
Specifies the deceleration rate used by the velocity loop when the drive is
hardware disabled. (Fast stop ramp is not used when drive is software disabled.)
If the brake delay option is programmed, the fast stop ramp is used to decelerate
the motor before applying the brake.
Note that Fast Stop Ramp is used only in velocity mode. In position mode, the
trajectory generator handles controlled stopping of the motor. There is one
exception: if a non-latched following error occurs in position mode, then the drive
drops into velocity mode and the Fast Stop Ramp is used.
For more information, see Following Error Fault Details.
DIAGRAM:EFFECTS OF LIMITS ON VELOCITY COMMAND
The following diagram illustrates the effects of the velocity loop limits.
Commanded Velocity
Limited Velocity
Vel Limit
Accel Limit Decel Limit