Beckhoff EL3681 User Manual
Documentation | EN
EL3681
Digital Multimeter Terminal
2021-03-17 | Version: 2.6
Table of contents
Table of contents
1 Foreword ....................................................................................................................................................7
1.1 Notes on the documentation..............................................................................................................7
1.2 Safety instructions .............................................................................................................................8
1.3 Documentation issue status ..............................................................................................................9
1.4 Version identification of EtherCAT devices .....................................................................................10
1.4.1 Beckhoff Identification Code (BIC)................................................................................... 14
2 Product overview.....................................................................................................................................16
2.1 Introduction......................................................................................................................................16
2.2 Technical data .................................................................................................................................18
2.3 Technology ......................................................................................................................................19
2.4 Note on Beckhoff calibration certificates .........................................................................................22
2.5 Start .................................................................................................................................................24
3 Basics communication ...........................................................................................................................25
3.1 EtherCAT basics..............................................................................................................................25
3.2 EtherCAT cabling – wire-bound.......................................................................................................25
3.3 General notes for setting the watchdog...........................................................................................26
3.4 EtherCAT State Machine.................................................................................................................28
3.5 CoE Interface...................................................................................................................................29
3.6 Distributed Clock .............................................................................................................................34
4 Mounting and wiring................................................................................................................................35
4.1 Instructions for ESD protection........................................................................................................35
4.2 Installation on mounting rails ...........................................................................................................35
4.3 Connection ......................................................................................................................................38
4.3.1 Connection system .......................................................................................................... 38
4.3.2 Wiring............................................................................................................................... 41
4.3.3 Shielding .......................................................................................................................... 42
4.4 Positioning of passive Terminals .....................................................................................................43
4.5 Installation positions ........................................................................................................................43
4.6 LEDs and connection ......................................................................................................................46
5 Commissioning........................................................................................................................................47
5.1 TwinCAT Quick Start .......................................................................................................................47
5.1.1 TwinCAT 2 ....................................................................................................................... 50
5.1.2 TwinCAT 3 ....................................................................................................................... 60
5.2 TwinCAT Development Environment ..............................................................................................73
5.2.1 Installation of the TwinCAT real-time driver..................................................................... 74
5.2.2 Notes regarding ESI device description........................................................................... 79
5.2.3 TwinCAT ESI Updater ..................................................................................................... 83
5.2.4 Distinction between Online and Offline............................................................................ 83
5.2.5 OFFLINE configuration creation ...................................................................................... 84
5.2.6 ONLINE configuration creation ........................................................................................ 89
5.2.7 EtherCAT subscriber configuration.................................................................................. 97
5.2.8 Import/Export of EtherCAT devices with SCI and XTI ................................................... 106
5.3 General Notes - EtherCAT Slave Application................................................................................112
EL3681 3Version: 2.6
Table of contents
5.4 Notices on analog specifications ...................................................................................................120
5.4.1 Full scale value (FSV).................................................................................................... 120
5.4.2 Measuring error/ measurement deviation ...................................................................... 120
5.4.3 Temperature coefficient tK [ppm/K] ............................................................................... 121
5.4.4 Long-term use................................................................................................................ 122
5.4.5 Single-ended/differential typification .............................................................................. 122
5.4.6 Common-mode voltage and reference ground (based on differential inputs)................ 127
5.4.7 Dielectric strength .......................................................................................................... 127
5.4.8 Temporal aspects of analog/digital conversion.............................................................. 128
5.5 Basic function principles/functional description .............................................................................131
5.5.1 Measuring ranges and output ........................................................................................ 131
5.5.2 Selecting a measuring range ........................................................................................ 131
5.5.3 Autorange ...................................................................................................................... 132
5.5.4 Filter............................................................................................................................... 132
5.5.5 Frequency...................................................................................................................... 132
5.5.6 Presentation................................................................................................................... 133
5.5.7 Zero Compensation Interval .......................................................................................... 133
5.5.8 Calibration...................................................................................................................... 133
5.6 Process data..................................................................................................................................134
5.6.1 Process image ............................................................................................................... 134
5.6.2 Control, Status, Settings-Word ...................................................................................... 135
5.6.3 PDO Assignment ........................................................................................................... 136
5.6.4 Calculation of process data ........................................................................................... 137
5.6.5 Determining (user) gain values...................................................................................... 138
5.7 Object description and parameterization .......................................................................................139
5.7.1 Restore object................................................................................................................ 140
5.7.2 Configuration data ......................................................................................................... 141
5.7.3 Configuration data (vendor-specific).............................................................................. 143
5.7.4 Input data....................................................................................................................... 144
5.7.5 Output data .................................................................................................................... 145
5.7.6 Information and diagnostic data..................................................................................... 145
5.7.7 Standard objects (0x1000-0x1FFF) ............................................................................... 145
5.8 Sample Program............................................................................................................................149
6 Error handling and diagnostics............................................................................................................154
7 Appendix ................................................................................................................................................155
7.1 Accessories ...................................................................................................................................155
7.2 EtherCAT AL Status Codes...........................................................................................................156
7.3 Firmware compatibility...................................................................................................................157
7.4 Firmware Update EL/ES/EM/ELM/EPxxxx ....................................................................................158
7.4.1 Device description ESI file/XML..................................................................................... 159
7.4.2 Firmware explanation .................................................................................................... 162
7.4.3 Updating controller firmware *.efw................................................................................. 163
7.4.4 FPGA firmware *.rbf....................................................................................................... 164
7.4.5 Simultaneous updating of several EtherCAT devices.................................................... 168
7.5 Restoring the delivery state ...........................................................................................................169
EL36814 Version: 2.6
Table of contents
7.6 Support and Service ......................................................................................................................170
EL3681 5Version: 2.6
Table of contents
EL36816 Version: 2.6
Foreword
1 Foreword
1.1 Notes on the documentation
Intended audience
This description is only intended for the use of trained specialists in control and automation engineering who
are familiar with the applicable national standards.
It is essential that the documentation and the following notes and explanations are followed when installing
and commissioning these components.
It is the duty of the technical personnel to use the documentation published at the respective time of each
installation and commissioning.
The responsible staff must ensure that the application or use of the products described satisfy all the
requirements for safety, including all the relevant laws, regulations, guidelines and standards.
Disclaimer
The documentation has been prepared with care. The products described are, however, constantly under
development.
We reserve the right to revise and change the documentation at any time and without prior announcement.
No claims for the modification of products that have already been supplied may be made on the basis of the
data, diagrams and descriptions in this documentation.
Trademarks
Beckhoff®, TwinCAT®, EtherCAT®, EtherCATG®, EtherCATG10®, EtherCATP®, SafetyoverEtherCAT®,
TwinSAFE®, XFC®, XTS® and XPlanar® are registered trademarks of and licensed by Beckhoff Automation
GmbH. Other designations used in this publication may be trademarks whose use by third parties for their
own purposes could violate the rights of the owners.
Patent Pending
The EtherCAT Technology is covered, including but not limited to the following patent applications and
patents: EP1590927, EP1789857, EP1456722, EP2137893, DE102015105702 with corresponding
applications or registrations in various other countries.
EtherCAT® is registered trademark and patented technology, licensed by Beckhoff Automation GmbH,
Germany.
Copyright
© Beckhoff Automation GmbH & Co. KG, Germany.
The reproduction, distribution and utilization of this document as well as the communication of its contents to
others without express authorization are prohibited.
Offenders will be held liable for the payment of damages. All rights reserved in the event of the grant of a
patent, utility model or design.
EL3681 7Version: 2.6
Foreword
1.2 Safety instructions
Safety regulations
Please note the following safety instructions and explanations!
Product-specific safety instructions can be found on following pages or in the areas mounting, wiring,
commissioning etc.
Exclusion of liability
All the components are supplied in particular hardware and software configurations appropriate for the
application. Modifications to hardware or software configurations other than those described in the
documentation are not permitted, and nullify the liability of Beckhoff Automation GmbH & Co. KG.
Personnel qualification
This description is only intended for trained specialists in control, automation and drive engineering who are
familiar with the applicable national standards.
Description of instructions
In this documentation the following instructions are used.
These instructions must be read carefully and followed without fail!
DANGER
Serious risk of injury!
Failure to follow this safety instruction directly endangers the life and health of persons.
WARNING
Risk of injury!
Failure to follow this safety instruction endangers the life and health of persons.
CAUTION
Personal injuries!
Failure to follow this safety instruction can lead to injuries to persons.
NOTE
Damage to environment/equipment or data loss
Failure to follow this instruction can lead to environmental damage, equipment damage or data loss.
Tip or pointer
This symbol indicates information that contributes to better understanding.
EL36818 Version: 2.6
1.3 Documentation issue status
Version Comment
2.6 • Addenda EL3681-0020 and EL3681-0030
• Update chapter "Technical data"
• Update structure
• Update revision status
2.5 • Update chapter "UL notes"
• Update structure
2.4 • Update chapter "Technical data"
• Update structure
• Update revision status
2.3 • Update chapter "Sample Program"
• Update structure
• Update revision status
2.2 • Addenda chapter "Instructions for ESD protection"
• Addenda chapter "Notices on Analog specification"
2.1 • Update chapter "Notes on the documentation"
• Correction of Technical data
• Update chapter "TwinCAT 2.1x" -> "TwinCAT Development Environment" and
"TwinCAT Quick Start"
• Update revision status
2.0 • Migration
• Update structure
1.6 • Update structure
• Update chapter "Technical data"
1.5 • Update chapter "Basic function principles"
1.4 • Update firmware status
• Update chapter "Technology"
1.3 • Update firmware status
• Update application note
1.2 • Update TrueRMS, Crest factor
1.1 • Update LED description
1.0 • First public issue
0.2 • Corrections and addenda
0.1 • Preliminary documentation for EL3681
Foreword
EL3681 9Version: 2.6
Foreword
1.4 Version identification of EtherCAT devices
Designation
A Beckhoff EtherCAT device has a 14-digit designation, made up of
• family key
• type
• version
• revision
Example Family Type Version Revision
EL3314-0000-0016 EL terminal
(12 mm, nonpluggable connection
level)
ES3602-0010-0017 ES terminal
(12 mm, pluggable
connection level)
CU2008-0000-0000 CU device 2008 (8-port fast ethernet switch) 0000 (basic type) 0000
3314 (4-channel thermocouple
terminal)
3602 (2-channel voltage
measurement)
0000 (basic type) 0016
0010 (highprecision version)
0017
Notes
• The elements mentioned above result in the technical designation. EL3314-0000-0016 is used in the
example below.
• EL3314-0000 is the order identifier, in the case of “-0000” usually abbreviated to EL3314. “-0016” is the
EtherCAT revision.
• The order identifier is made up of
- family key (EL, EP, CU, ES, KL, CX, etc.)
- type (3314)
- version (-0000)
• The revision -0016 shows the technical progress, such as the extension of features with regard to the
EtherCAT communication, and is managed by Beckhoff.
In principle, a device with a higher revision can replace a device with a lower revision, unless specified
otherwise, e.g. in the documentation.
Associated and synonymous with each revision there is usually a description (ESI, EtherCAT Slave
Information) in the form of an XML file, which is available for download from the Beckhoff web site.
From 2014/01 the revision is shown on the outside of the IP20 terminals, see Fig. “EL5021 EL terminal,
standard IP20 IO device with batch number and revision ID (since 2014/01)”.
• The type, version and revision are read as decimal numbers, even if they are technically saved in
hexadecimal.
Identification number
Beckhoff EtherCAT devices from the different lines have different kinds of identification numbers:
Production lot/batch number/serial number/date code/D number
The serial number for Beckhoff IO devices is usually the 8-digit number printed on the device or on a sticker.
The serial number indicates the configuration in delivery state and therefore refers to a whole production
batch, without distinguishing the individual modules of a batch.
Structure of the serial number: KKYYFFHH
KK - week of production (CW, calendar week)
YY - year of production
FF - firmware version
HH - hardware version
EL368110 Version: 2.6
Foreword
Example with
Ser. no.: 12063A02: 12 - production week 12 06 - production year 2006 3A - firmware version 3A 02 hardware version 02
Exceptions can occur in the IP67 area, where the following syntax can be used (see respective device
documentation):
Syntax: D ww yy x y z u
D - prefix designation
ww - calendar week
yy - year
x - firmware version of the bus PCB
y - hardware version of the bus PCB
z - firmware version of the I/O PCB
u - hardware version of the I/O PCB
Example: D.22081501 calendar week 22 of the year 2008 firmware version of bus PCB: 1 hardware version
of bus PCB: 5 firmware version of I/O PCB: 0 (no firmware necessary for this PCB) hardware version of I/O
PCB: 1
Unique serial number/ID, ID number
In addition, in some series each individual module has its own unique serial number.
See also the further documentation in the area
• IP67: EtherCAT Box
• Safety: TwinSafe
• Terminals with factory calibration certificate and other measuring terminals
Examples of markings
Fig.1: EL5021 EL terminal, standard IP20 IO device with serial/ batch number and revision ID (since
2014/01)
EL3681 11Version: 2.6
Foreword
Fig.2: EK1100 EtherCAT coupler, standard IP20 IO device with serial/ batch number
Fig.3: CU2016 switch with serial/ batch number
Fig.4: EL3202-0020 with serial/ batch number 26131006 and unique ID-number 204418
EL368112 Version: 2.6
Foreword
Fig.5: EP1258-00001 IP67 EtherCAT Box with batch number/ date code 22090101 and unique serial
number 158102
Fig.6: EP1908-0002 IP67 EtherCAT Safety Box with batch number/ date code 071201FF and unique serial
number 00346070
Fig.7: EL2904 IP20 safety terminal with batch number/ date code 50110302 and unique serial number
00331701
Fig.8: ELM3604-0002 terminal with unique ID number (QR code) 100001051 and serial/ batch number
44160201
EL3681 13Version: 2.6
Foreword
1.4.1 Beckhoff Identification Code (BIC)
The Beckhoff Identification Code (BIC) is increasingly being applied to Beckhoff products to uniquely identify
the product. The BIC is represented as a Data Matrix Code (DMC, code scheme ECC200), the content is
based on the ANSI standard MH10.8.2-2016.
Fig.9: BIC as data matrix code (DMC, code scheme ECC200)
The BIC will be introduced step by step across all product groups.
Depending on the product, it can be found in the following places:
• on the packaging unit
• directly on the product (if space suffices)
• on the packaging unit and the product
The BIC is machine-readable and contains information that can also be used by the customer for handling
and product management.
Each piece of information can be uniquely identified using the so-called data identifier
(ANSIMH10.8.2-2016). The data identifier is followed by a character string. Both together have a maximum
length according to the table below. If the information is shorter, spaces are added to it. The data under
positions 1 to 4 are always available.
The following information is contained:
EL368114 Version: 2.6
Item
Type of
no.
information
1 Beckhoff order
number
2 Beckhoff Traceability
Number (BTN)
3 Article description Beckhoff article
4 Quantity Quantity in packaging
5 Batch number Optional: Year and week
6 ID/serial number Optional: Present-day
7 Variant number Optional: Product variant
...
Explanation Data
Beckhoff order number 1P 8 1P072222
Unique serial number,
see note below
description, e.g.
EL1008
unit, e.g. 1, 10, etc.
of production
serial number system,
e.g. with safety products
or calibrated terminals
number on the basis of
standard products
Foreword
Number of digits
identifier
S 12 SBTNk4p562d7
1K 32 1KEL1809
Q 6 Q1
2P 14 2P401503180016
51S 12 51S678294104
30P 32 30PF971, 2*K183
incl. data identifier
Example
Further types of information and data identifiers are used by Beckhoff and serve internal processes.
Structure of the BIC
Example of composite information from item 1 to 4 and 6. The data identifiers are marked in red for better
display:
BTN
An important component of the BIC is the Beckhoff Traceability Number (BTN, item no.2). The BTN is a
unique serial number consisting of eight characters that will replace all other serial number systems at
Beckhoff in the long term (e.g. batch designations on IO components, previous serial number range for
safety products, etc.). The BTN will also be introduced step by step, so it may happen that the BTN is not yet
coded in the BIC.
NOTE
This information has been carefully prepared. However, the procedure described is constantly being further
developed. We reserve the right to revise and change procedures and documentation at any time and without prior notice. No claims for changes can be made from the information, illustrations and descriptions in
this information.
EL3681 15Version: 2.6
Product overview
2 Product overview
2.1 Introduction
Fig.10: EL3681
Digital multimeter terminal
The EL3681 EtherCAT Terminal enables measurement of currents and voltages in wide input range. The
measuring ranges are switched automatically, as usual in advanced digital multimeters. There are two
current paths available for current measurement. One of them is a high current path for up to 10 A.
The current and the voltage measurement facility can be used for DC and AC. The alternating parameters
are output as true RMS values. The input signal can cover a range up to 1 kHz, without affecting the
measuring accuracy. A non-sinus signal form is allowed, if the Crest factor is < 3.
The measurement readings can be read and processed with EtherCAT. At the same time, the EL3681
enables the measuring type and range to be set via the bus.
Excellent interference immunity is achieved through the fully electrically isolated design of the electronic
measuring system and the dual slope conversion system. High precision and simple, high impedance
measurement from 300 mV to 300 V allow the EtherCAT terminals to be used like a modern digital
multimeter. The sample rate lies between approx. 500 ms if the filter is activated and approx. 62 ms if the
filter is deactivated.
The selected measuring type and overload are indicated by LEDs.
In measuring applications in particular, the voltage to be expected is often not yet known during the planning
phase. Automatic adjustment of the measurement range simplifies use and reduces stock levels.
As high-precision variants, the EL3681-0020 with individual factory calibration certificate and the EL3681-0030
with external calibration certificate are available.
Please read the notes on the calibration certificate [}22] and identification features [}22] of these
terminals.
EL368116 Version: 2.6
Quick links
• EtherCAT basics
• Basic function principles EL3681 [}131]
• Process data [}134]
• CoE object description and parameterization [}139]
• Sample programs [}149]
• Error handling [}154]
• Accessories [}155]
Product overview
EL3681 17Version: 2.6
Product overview
2.2 Technical data
Technical data EL3681 EL3681-0020 EL3681-0030
Measured values current, voltage (AC/DC)
Measuring voltage 300mV, 3V, 30V, 300V
Measuring current 100 mA, 1 A and 10 A via high-current path
Resolution 18 bit + sign in each measurement range
Internal resistance Measuring range DC 300 mV - 300 V: 12.5MΩ
Measuring range DC 100 mA - 1 A: 0.2 Ω
Measuring range DC 10A: 3mΩ
Measuring range AC 300mV - 300V: 1MΩ, approx. 33pF
Measuring rangeAC 100 mA - 1 A: 0.2 Ω
Measuring range AC 10A: 3mΩ
Measuring error
Measuring procedure DC with arithmetic averaging
Update time 0.5 s, 1 s for measuring range selection
Electrical isolation 1,500V (connection terminal/E-bus)
Supply voltage for electronic via the E-bus
Current consumption via E-bus typ. 150 mA
Configuration via TwinCAT System Manager
Weight approx. 70 g
Permissible ambient temperature range during operation
Permissible ambient temperature range during storage -40 °C ... +85 °C
Permissible relative humidity 95%, no condensation
Dimensions (W x H x D) approx. 15 mm x 100 mm x 70 mm (width aligned: 12 mm)
Mounting [}35]
Vibration/shock resistance conforms to EN 60068-2-6 / EN 60068-2-27
EMC immunity/emission conforms to EN 61000-6-2 / EN 61000-6-4
Protection class IP20
Installation position variable
Approval / marking CE CE
see table [}20] in chapter “Accuracy”
AC with TrueRMS, 0..1 kHz input signal, Crest factor < 3 allowed
-25 °C ... +60 °C (extended temperature range)
on 35 mm mounting rail conforms to EN 60715
CE
with factory calibration
certificate [}22]
with external calibration
certificate [}22]
EL368118 Version: 2.6
Product overview
2.3 Technology
Table of contents
General description [}19]
Specifications [}20]
- Accuracy [}20]
- Internal resistances [}21] - Fuse [}21]
Default setting [}21]
General description
The functionality of the EL3681 is similar to that of a commercial digital multimeter. The terminal offers the
following features:
• Single-channel measurement
• AC/DC voltage measurement, range selection automatic through Autorange function or through the
controller; measuring ranges 300mV, 3V, 30V, 300V
• AC/DC current measurement in the 1A path (internal fuse: 1.25A) or 10A path (no internal fuse),
measuring ranges: 100mA, 1A, 10A
• Formation of measured values:
AC current/voltage is calculated as a true RMS value without DC component, an integration of the
signal waveform in the ADC takes place
DC current/voltage is calculated as an arithmetic mean value, an integration of the signal waveform in
the ADC takes place
• Electrical isolation from the fieldbus
• Very good interference immunity through dual-slope conversion technique
• Display of measurement type (current/voltage) and overload through LED
• Typical update rate approx. 2/s, after measuring range change up to approx. 1/s, with deactivated filter
approx. 16/s.
The data collection is shown in fig. Data flow EL3681.
Fig.11: Data flow EL3681
Application note
For the measurement of a 60Hz signal, the CoE(0x8000:0A [}141])object should be set accordingly. For all
other signal frequencies the 50Hz preset is valid, because of the longer integration time. The accuracy
information shown below refer to a input signal of a frequency range of >0 .. 1kHz. With higher frequencies
the measurement accuracy decreases (-3dB>500kHz).
It is possible to measure a non-sinus AC input signal, if the Crest factor is < 3. The accuracy information
below refers to a Crest factor of max. 2.
EL3681 19Version: 2.6
Product overview
The simultaneous electrical connection of both current paths (10, 1A) and the voltage path for a following
alternating measurement of values is possible, but not recommended. In case of AC components in the
signal, a parasitic crosstalk from path to path can occur. After switching over, the process data update time
can be up to 1 second.
Specifications
Accuracy
The unused measurement input should be connected to the COM port of the terminal in order to make the
analysis as accurate as possible and minimize interference.
• Possible measuring inputs at the terminal:
◦ Voltage measurement 300mV – 300V (connection points 1 + 5)
◦ Current measurement 100mA – 1A (connection point 7)
◦ Current measurement 10A (connection point 3)
The measuring accuracy depends on the type of signal to be measures and on the terminal settings.
The accuracy values specified in the following table apply to the default settings for the terminal parameters:
- Enable vendor calibration true
- Enable filter true
- Frequency 50 Hz
- Zero compensation interval Off (0)
- Presentation Scaled (1Bit/1µV) (2)
Signal to be measured Typical max. tolerance in % of full scale
Measure-
Measuring range 40°C
value
1)
3)
0 .. 55°C ppm/°C
Typical temperature drift
2)6)
ment type
DC 3V - 300V
300mV
100mA
8)
8)
7)
0.01 0.2 35
0.05 0.2 35
0.1 0.5 50
1A 0.1 0.5 50
10A 0.2 1.2 170
4) 5)
AC
3V - 300V 0.25 0.75 130
300mV 0.25 0.5 50
100mA 0.5 1 50
1A 0.5 0.7 50
10A 0.5 1.2 150
Table 1: Measuring tolerances depending on temperatures. MBE = full scale value.
1) In 60Hz mode of ADC 0.02 should be added to the specified tolerance
2) The values apply to a minimum terminal warm-up time of 30 minutes
3) The compensation temperature is 40 °C
4) All AC voltage and current ranges are specified for a range of 5% to 100%
5) Crest factor < 2
6) In 60 Hz mode an additional temperature drift of 20 ppm / °C is to be expected.
7) The maximum deviation under EMC test conditions according to IEC 61131 is 1 %
8) The maximum deviation under EMC test conditions according to IEC 61131 is 0.2 %
Measuring procedure
The measuring technique in the terminal is based on the dual-slope technique.
The Zero Offset Compensation function reads the internal ADC offset and corrects the analog value
accordingly. The additional temperature drift can thus be partly compensated, either cyclically or through
external control.
EL368120 Version: 2.6
Product overview
Operating conditions
• To avoid interference shielded cables must be used for the analog signals. The maximum cable length
is 30m.
• For DC voltage measurements may the AC component may not exceed 150Vpp.
• For AC voltage measurements may the DC component may not exceed 150V (sine voltage).
• The peak voltage (relative to the COM terminal) may not exceed 600V.
Internal resistance
Measurement type Measuring range Internal resistance
DC 300mV - 300V 12.5MΩ
100mA - 1A 0.2Ω
10A 3mΩ
4) 5)
AC
300mV - 300V 1MΩ, approx. 33pF
100mA - 1A 0.2Ω
10A 3mΩ
Table 2: Internal resistances
Fuse
Notes on replacing the fuse can be found in section Accessories [}155].
Default Setting
The factory setting for the multimeter terminal enables voltages up to 300VDC to be measured directly
without additional settings. The Autorange function is active and selects the measuring range automatically.
The measured value is displayed with 1 bit/µV, i.e. no adjustment is required. Fig. Display of measured value
in TwinCAT shows an example for measured values in the TwinCAT tree. In the example the value
10448400 corresponds to a voltage of 10.448400 V
Fig.12: Display of measured value in TwinCAT
The terminal is supplied with a sample program [}149] that enables the process data of the EL3681 to be
modified and the terminal to be re-parameterized.
EL3681 21Version: 2.6
Product overview
2.4 Note on Beckhoff calibration certificates
Basically every Beckhoff analogue device (input or output) will be justified i.e. will be calibrated during
production. This procedure won’t be documented unique. This documentation as a calibration certificate is
only provided for devices that are expressly delivered with a certificate.
The calibration certificate (or German: “Kalibrierschein”) entitles the residual error after compensation/
adjustment to the used standard (reference device). The calibration certificate (as a PDF document) is to be
assigned to the device via a unique number. It is therefore not a statement about a device class such as e.g.
an approval, but always only applies to a single, named device. It is available for download.
The calibration certificate documents the measurement accuracy at the time the certificate was issued and
contains, among other things, information on the ambient conditions and the reference instrument used. It
does not contain statement about the behavior or the change of the measuring accuracy in the future. A
calibration certificate acts as a backtracking view to the previous time of usage. By reiterated certification
procedures over years (without justification) it allows making conclusions about its ageing behavior, so called
calibrate history.
Performance levels of the calibration certificates
Different "qualities" of a calibration certificate are common:
• Beckhoff calibration certificates
Such IP20 terminals can be usually identified by the product suffix -0020. The certificate is issued in
Beckhoff production as PDF.
The terminals can be obtained from Beckhoff and recalibrated by the Beckhoff service department.
• ISO17025 calibration certificates
Such IP20 terminals can be usually identified by the product suffix -0030. The certificate is issued by a
service provider on behalf of Beckhoff as part of Beckhoff production and delivered by Beckhoff as a
PDF.
The terminals can be obtained from Beckhoff and recalibrated by the Beckhoff service department.
• DAkkS calibration certificates (German: "Deutsche Akkreditierungsstelle GmbH")
Such IP20 terminals can be usually identified by the product suffix -0030. The certificate is issued by a
accredited service provider on behalf of Beckhoff as a part of Beckhoff production and delivered by
Beckhoff as a PDF.
The terminals can be obtained from Beckhoff and recalibrated by the Beckhoff service department.
EL368122 Version: 2.6
Unique device number
Depending on the device, the following numbers are used for identification:
• EL/ELM terminals up to year of manufacture 2020: the ID number which is lasered on the side.
Product overview
Fig.13: ID number
• From year of manufacture 2021 onwards, the BTN number (Beckhoff Traceability Number) will
gradually replace the ID number, this is also lasered on the side.
Beckhoff produces a wide range of analog input/output devices as IP20 terminal or IP67 box. A selection of
these is also available with factory/ISO/DAkkS calibration certificates. For specific details and availability, see
the technical data of the devices or contact Beckhoff Sales.
Linguistic note
In American English, "calibration" or "alignment" is understood to mean compensation/adjustment,
thus a modifying effect on the device. "Verification", on the other hand, refers to observational determination and documentation of the residual error, referred in German language use as “Kalib-
rierung”.
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Product overview
2.5 Start
For commissioning:
• mount the EL3681 as described in the chapter Mounting and wiring [}35]
• configure the EL3681 in TwinCAT as described in the chapter Commissioning [}131].
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3 Basics communication
3.1 EtherCAT basics
Please refer to the EtherCAT System Documentation for the EtherCAT fieldbus basics.
3.2 EtherCAT cabling – wire-bound
The cable length between two EtherCAT devices must not exceed 100 m. This results from the FastEthernet
technology, which, above all for reasons of signal attenuation over the length of the cable, allows a maximum
link length of 5 + 90 + 5 m if cables with appropriate properties are used. See also the Design
recommendations for the infrastructure for EtherCAT/Ethernet.
Cables and connectors
For connecting EtherCAT devices only Ethernet connections (cables + plugs) that meet the requirements of
at least category 5 (CAt5) according to EN 50173 or ISO/IEC 11801 should be used. EtherCAT uses 4 wires
for signal transfer.
EtherCAT uses RJ45 plug connectors, for example. The pin assignment is compatible with the Ethernet
standard (ISO/IEC 8802-3).
Pin Color of conductor Signal Description
1 yellow TD + Transmission Data +
2 orange TD - Transmission Data -
3 white RD + Receiver Data +
6 blue RD - Receiver Data -
Due to automatic cable detection (auto-crossing) symmetric (1:1) or cross-over cables can be used between
EtherCAT devices from Beckhoff.
Recommended cables
It is recommended to use the appropriate Beckhoff components e.g.
- cable sets ZK1090-9191-xxxx respectively
- RJ45 connector, field assembly ZS1090-0005
- EtherCAT cable, field assembly ZB9010, ZB9020
Suitable cables for the connection of EtherCAT devices can be found on the Beckhoff website!
E-Bus supply
A bus coupler can supply the EL terminals added to it with the E-bus system voltage of 5V; a coupler is
thereby loadable up to 2A as a rule (see details in respective device documentation).
Information on how much current each EL terminal requires from the E-bus supply is available online and in
the catalogue. If the added terminals require more current than the coupler can supply, then power feed
terminals (e.g. EL9410) must be inserted at appropriate places in the terminal strand.
The pre-calculated theoretical maximum E-Bus current is displayed in the TwinCAT System Manager. A
shortfall is marked by a negative total amount and an exclamation mark; a power feed terminal is to be
placed before such a position.
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Basics communication
Fig.14: System manager current calculation
NOTE
Malfunction possible!
The same ground potential must be used for the E-Bus supply of all EtherCAT terminals in a terminal block!
3.3 General notes for setting the watchdog
ELxxxx terminals are equipped with a safety feature (watchdog) that switches off the outputs after a
specifiable time e.g. in the event of an interruption of the process data traffic, depending on the device and
settings, e.g. in OFF state.
The EtherCAT slave controller (ESC) in the EL2xxx terminals features two watchdogs:
• SM watchdog (default: 100 ms)
• PDI watchdog (default: 100 ms)
SM watchdog (SyncManager Watchdog)
The SyncManager watchdog is reset after each successful EtherCAT process data communication with the
terminal. If no EtherCAT process data communication takes place with the terminal for longer than the set
and activated SM watchdog time, e.g. in the event of a line interruption, the watchdog is triggered and the
outputs are set to FALSE. The OP state of the terminal is unaffected. The watchdog is only reset after a
successful EtherCAT process data access. Set the monitoring time as described below.
The SyncManager watchdog monitors correct and timely process data communication with the ESC from the
EtherCAT side.
PDI watchdog (Process Data Watchdog)
If no PDI communication with the EtherCAT slave controller (ESC) takes place for longer than the set and
activated PDI watchdog time, this watchdog is triggered.
PDI (Process Data Interface) is the internal interface between the ESC and local processors in the EtherCAT
slave, for example. The PDI watchdog can be used to monitor this communication for failure.
The PDI watchdog monitors correct and timely process data communication with the ESC from the
application side.
The settings of the SM- and PDI-watchdog must be done for each slave separately in the TwinCAT System
Manager.
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Fig.15: EtherCAT tab -> Advanced Settings -> Behavior -> Watchdog
Notes:
• the multiplier is valid for both watchdogs.
• each watchdog has its own timer setting, the outcome of this in summary with the multiplier is a
resulting time.
• Important: the multiplier/timer setting is only loaded into the slave at the start up, if the checkbox is
activated.
If the checkbox is not activated, nothing is downloaded and the ESC settings remain unchanged.
Multiplier
Both watchdogs receive their pulses from the local terminal cycle, divided by the watchdog multiplier:
1/25 MHz * (watchdog multiplier + 2) = 100µs (for default setting of 2498 for the multiplier)
The standard setting of 1000 for the SM watchdog corresponds to a release time of 100ms.
The value in multiplier + 2 corresponds to the number of basic 40 ns ticks representing a watchdog tick.
The multiplier can be modified in order to adjust the watchdog time over a larger range.
Example “Set SM watchdog”
This checkbox enables manual setting of the watchdog times. If the outputs are set and the EtherCAT
communication is interrupted, the SM watchdog is triggered after the set time and the outputs are erased.
This setting can be used for adapting a terminal to a slower EtherCAT master or long cycle times. The
default SM watchdog setting is 100ms. The setting range is 0...65535. Together with a multiplier with a
range of 1...65535 this covers a watchdog period between 0...~170 seconds.
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Calculation
Multiplier = 2498 → watchdog base time = 1 / 25MHz * (2498 + 2) = 0.0001seconds = 100µs
SM watchdog = 10000 → 10000 * 100µs = 1second watchdog monitoring time
CAUTION
Undefined state possible!
The function for switching off of the SM watchdog via SM watchdog = 0 is only implemented in terminals
from version -0016. In previous versions this operating mode should not be used.
CAUTION
Damage of devices and undefined state possible!
If the SM watchdog is activated and a value of 0 is entered the watchdog switches off completely. This is
the deactivation of the watchdog! Set outputs are NOT set in a safe state, if the communication is interrupted.
3.4 EtherCAT State Machine
The state of the EtherCAT slave is controlled via the EtherCAT State Machine (ESM). Depending upon the
state, different functions are accessible or executable in the EtherCAT slave. Specific commands must be
sent by the EtherCAT master to the device in each state, particularly during the bootup of the slave.
A distinction is made between the following states:
• Init
• Pre-Operational
• Safe-Operational and
• Operational
• Boot
The regular state of each EtherCAT slave after bootup is the OP state.
Fig.16: States of the EtherCAT State Machine
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Init
After switch-on the EtherCAT slave in the Init state. No mailbox or process data communication is possible.
The EtherCAT master initializes sync manager channels 0 and 1 for mailbox communication.
Pre-Operational (Pre-Op)
During the transition between Init and Pre-Op the EtherCAT slave checks whether the mailbox was initialized
correctly.
In Pre-Op state mailbox communication is possible, but not process data communication. The EtherCAT
master initializes the sync manager channels for process data (from sync manager channel 2), the FMMU
channels and, if the slave supports configurable mapping, PDO mapping or the sync manager PDO
assignment. In this state the settings for the process data transfer and perhaps terminal-specific parameters
that may differ from the default settings are also transferred.
Safe-Operational (Safe-Op)
During transition between Pre-Op and Safe-Op the EtherCAT slave checks whether the sync manager
channels for process data communication and, if required, the distributed clocks settings are correct. Before
it acknowledges the change of state, the EtherCAT slave copies current input data into the associated DPRAM areas of the EtherCAT slave controller (ECSC).
In Safe-Op state mailbox and process data communication is possible, although the slave keeps its outputs
in a safe state, while the input data are updated cyclically.
Outputs in SAFEOP state
The default set watchdog [}26] monitoring sets the outputs of the module in a safe state - depending on the settings in SAFEOP and OP - e.g. in OFF state. If this is prevented by deactivation of the
watchdog monitoring in the module, the outputs can be switched or set also in the SAFEOP state.
Operational (Op)
Before the EtherCAT master switches the EtherCAT slave from Safe-Op to Op it must transfer valid output
data.
In the Op state the slave copies the output data of the masters to its outputs. Process data and mailbox
communication is possible.
Boot
In the Boot state the slave firmware can be updated. The Boot state can only be reached via the Init state.
In the Boot state mailbox communication via the file access over EtherCAT (FoE) protocol is possible, but no
other mailbox communication and no process data communication.
3.5 CoE Interface
General description
The CoE interface (CAN application protocol over EtherCAT)) is used for parameter management of
EtherCAT devices. EtherCAT slaves or the EtherCAT master manage fixed (read only) or variable
parameters which they require for operation, diagnostics or commissioning.
CoE parameters are arranged in a table hierarchy. In principle, the user has read access via the fieldbus.
The EtherCAT master (TwinCAT System Manager) can access the local CoE lists of the slaves via
EtherCAT in read or write mode, depending on the attributes.
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Different CoE parameter types are possible, including string (text), integer numbers, Boolean values or larger
byte fields. They can be used to describe a wide range of features. Examples of such parameters include
manufacturer ID, serial number, process data settings, device name, calibration values for analog
measurement or passwords.
The order is specified in two levels via hexadecimal numbering: (main)index, followed by subindex. The
value ranges are
• Index: 0x0000 …0xFFFF (0...65535
• SubIndex: 0x00…0xFF (0...255
dez
)
dez
)
A parameter localized in this way is normally written as 0x8010:07, with preceding “0x” to identify the
hexadecimal numerical range and a colon between index and subindex.
The relevant ranges for EtherCAT fieldbus users are:
• 0x1000: This is where fixed identity information for the device is stored, including name, manufacturer,
serial number etc., plus information about the current and available process data configurations.
• 0x8000: This is where the operational and functional parameters for all channels are stored, such as
filter settings or output frequency.
Other important ranges are:
• 0x4000: here are the channel parameters for some EtherCAT devices. Historically, this was the first
parameter area before the 0x8000 area was introduced. EtherCAT devices that were previously
equipped with parameters in 0x4000 and changed to 0x8000 support both ranges for compatibility
reasons and mirror internally.
• 0x6000: Input PDOs (“input” from the perspective of the EtherCAT master)
• 0x7000: Output PDOs (“output” from the perspective of the EtherCAT master)
Availability
Not every EtherCAT device must have a CoE list. Simple I/O modules without dedicated processor
usually have no variable parameters and therefore no CoE list.
If a device has a CoE list, it is shown in the TwinCAT System Manager as a separate tab with a listing of the
elements:
Fig.17: “CoE Online” tab
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