Beckhoff EL2904 User manual

Operating instructions | EN
EL2904
TwinSAFE Terminal with 4 digital fail-safe outputs
2021-03-17 | Version: 2.3.0

Table of contents
EL2904 3Version: 2.3.0
Table of contents
1 Foreword ....................................................................................................................................................5
1.1 Notes on the documentation..............................................................................................................5
1.2 Safety instructions .............................................................................................................................6
1.2.1 Delivery state ..................................................................................................................... 6
1.2.2 Operator's obligation to exercise diligence ........................................................................ 6
1.2.3 Description of instructions.................................................................................................. 7
1.3 Documentation issue status ..............................................................................................................8
2 System description .................................................................................................................................10
2.1 The Beckhoff Bus Terminal system.................................................................................................10
2.1.1 Bus Coupler ..................................................................................................................... 11
2.1.2 Bus Terminals.................................................................................................................. 12
2.1.3 E-bus ............................................................................................................................... 12
2.1.4 Power contacts ................................................................................................................ 12
2.2 TwinSAFE........................................................................................................................................13
2.2.1 The I/O construction kit is extended safely ...................................................................... 13
2.2.2 Safety concept ................................................................................................................. 13
2.2.3 EL1904, EL2904 - Bus Terminals with 4 fail-safe inputs or outputs ................................ 14
2.2.4 EL6900 - TwinSAFE logic terminal .................................................................................. 14
2.2.5 The fail-safe principle (Fail Stop) ..................................................................................... 14
3 Product description.................................................................................................................................15
3.1 EL2904 – TwinSAFE terminal with 4 digital fail-safe outputs ..........................................................15
3.2 Intended use....................................................................................................................................16
3.3 Technical data .................................................................................................................................18
3.4 Safety parameters ...........................................................................................................................19
3.5 Dimensions......................................................................................................................................20
3.6 Block diagram of the EL2904 ..........................................................................................................21
4 Operation..................................................................................................................................................22
4.1 Environmental conditions ................................................................................................................22
4.2 Installation .......................................................................................................................................22
4.2.1 Safety instructions ........................................................................................................... 22
4.2.2 Transport / storage .......................................................................................................... 22
4.2.3 Electrical installation ........................................................................................................ 22
4.2.4 Mechanical installation..................................................................................................... 27
4.2.5 TwinSAFE reaction times ................................................................................................ 32
4.2.6 Tested EL2904 devices ................................................................................................... 33
4.3 Operation in potentially explosive atmospheres (ATEX) .................................................................34
4.3.1 Special conditions............................................................................................................ 34
4.3.2 Identification..................................................................................................................... 34
4.3.3 Date code and serial number........................................................................................... 35
4.3.4 Further ATEX documentation .......................................................................................... 35
4.4 Configuration of the terminal in TwinCAT........................................................................................35
4.4.1 Inserting a Bus Coupler ................................................................................................... 35
4.4.2 Inserting a Bus Terminal.................................................................................................. 35

Table of contents
EL29044 Version: 2.3.0
4.4.3 Inserting an EL2904......................................................................................................... 35
4.4.4 Address settings on TwinSAFE terminals with 1023 possible addresses ....................... 37
4.4.5 Entering a TwinSAFE address and parameters in the System Manager ........................ 38
4.5 Diagnostics ......................................................................................................................................40
4.5.1 Diagnostic LEDs .............................................................................................................. 40
4.5.2 Diagnostic objects............................................................................................................ 41
4.5.3 Possible causes of diagnostic messages ........................................................................ 43
4.6 Maintenance ....................................................................................................................................44
4.7 Service life .......................................................................................................................................44
4.8 Decommissioning ............................................................................................................................45
5 Appendix ..................................................................................................................................................46
5.1 Support and Service ........................................................................................................................46
5.2 Certificates.......................................................................................................................................47

Foreword
EL2904 5Version: 2.3.0
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 following notes and explanations are followed when installing and commissioning
these components.
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.
Origin of the document
This is a translation of the original instructions which are written in German. All other languages are derived
from the German original.
Currentness
Please check whether you are using the current and valid version of this document. The current version can
be downloaded from the Beckhoff homepage at https://www.beckhoff.com/twinsafe/. In case of doubt, please
contact Technical Support [}46].
Product features
Only the product features specified in the current user documentation are valid. Further information given on
the product pages of the Beckhoff homepage, in emails or in other publications is not authoritative.
Disclaimer
The documentation has been prepared with care. The products described are subject to cyclical revision. For
that reason the documentation is not in every case checked for consistency with performance data,
standards or other characteristics. 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®, TwinCAT/BSD®, TC/BSD®, EtherCAT®, EtherCATG®, EtherCATG10®, EtherCATP®,
SafetyoverEtherCAT®, 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.

Foreword
EL29046 Version: 2.3.0
EtherCAT® and Safety over EtherCAT® are registered trademarks and patented technologies, 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.
Delivery conditions
In addition, the general delivery conditions of the company Beckhoff Automation GmbH & Co. KG apply.
1.2 Safety instructions
1.2.1 Delivery state
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.
1.2.2 Operator's obligation to exercise diligence
The operator must ensure that
• the TwinSAFE products are only used as intended (see chapter Product description);
• the TwinSAFE products are only operated in sound condition and in working order.
• the TwinSAFE products are operated only by suitably qualified and authorized personnel.
• the personnel is instructed regularly about relevant occupational safety and environmental protection
aspects, and is familiar with the operating instructions and in particular the safety instructions contained
herein.
• the operating instructions are in good condition and complete, and always available for reference at the
location where the TwinSAFE products are used.
• none of the safety and warning notes attached to the TwinSAFE products are removed, and all notes
remain legible.

Foreword
EL2904 7Version: 2.3.0
1.2.3 Description of instructions
In these operating instructions 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 the 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.

Foreword
EL29048 Version: 2.3.0
1.3 Documentation issue status

Foreword
EL2904 9Version: 2.3.0
Version Comment
2.3.0 • Utilization category added
• Intended load added
• Overvoltage category added
• Protection class added
• Equipment type “open equipment” added
• “Level of contamination” replaced by “pollution degree”
• Chapter “Intended use”: “may” replaced by “shall”
• Currentness link updated
• Document origin: description changed
2.2.0 • Notes on heights, fuses and wiring added
• Notes on EN81 added
• Notes added in section Intended Use
• Chapter Identification (ATEX) updated
2.1.1 • Technical data for permissible air pressure expanded
2.1.0 • Chapter on Address settings on TwinSAFE terminals with 1023 possible addresses updated
• Links in technical data corrected
2.0.1 • Links in the chapter on Diagnostic LEDs corrected
2.0.0 • Migration and structural adaptation
• Reliability document updated
• Safety parameters updated
• Foreword revised
1.6.2 • Block diagram updated
• Numbering/table of contents changed
• Description of the reaction times added
• Reliability document updated
1.6.1 • Certificate updated
1.6.0 • Company address amended
• Safety parameters extended
1.5.0 • Extended temperature range amended
• Notes regarding temperature measurement and EMC added
• Description of date code extended
1.4.1 • Document origin added
1.4.0 • Note regarding cable length and signal routing extended
• Table listing causes for diagnostic messages amended
1.3.0 • Block diagram for EL2904 added
1.2.1 • Reference to EN60068-2-29 removed
1.2.0 • ATEX notes amended
• Installation position / minimum distances extended
• Notes regarding overvoltage protection amended
• Notes regarding cable length and clocked signals extended
• EN954 wiring example removed
• Diagnostics for CoE object 0x800E described
1.1.0 • Minor amendments for EtherCAT
• Copyright / disclaimer modified
• Support / service addresses updated
1.0.0 • First released version

System description
EL290410 Version: 2.3.0
2 System description
2.1 The Beckhoff Bus Terminal system
The Beckhoff Bus Terminal system is used for decentralized connection of sensors and actuators to a
control system. The Beckhoff Bus Terminal system components are mainly used in industrial automation and
building management applications. In its minimum configuration, a bus station consists of a Bus Coupler or a
Bus Terminal Controller and Bus Terminals connected to it. The Bus Coupler forms the communication
interface to the higher-level controller, and the terminals are the interface to sensors and actuators. The
whole bus station is clipped onto a 35 mm DIN mounting rail (EN 60715). The mechanical cross connection
of the bus station is established via a slot and key system at the Bus Coupler and the Bus Terminals.
The sensors and actuators are connected with the terminals via the screwless (spring-loaded) connection
system.
Fig.1: Slot and key system and screwless (spring-loaded) connection system.
In order to accommodate the wide range of different communication standards encountered in industrial
automation, Beckhoff offers Bus Couplers for a number of common bus systems (e.g. EK1100 for
EtherCAT).

System description
EL2904 11Version: 2.3.0
2.1.1 Bus Coupler
Mechanical data Bus Coupler
Material polycarbonate, polyamide (PA6.6).
Dimensions (W x H x D) 44mm x 100mm x 68mm
Mounting on 35 mm mounting rail (EN60715) with locking
Attachable by double slot and key connection
Fig.2: Bus Coupler (EtherCAT)
Connection technology Bus Coupler
Wiring spring-loaded system
Connection cross-section 0.08 mm² ... 2.5 mm², stranded wire, solid wire
Fieldbus connection depending on fieldbus
Power contacts 3 spring contacts
Current load 10A
Rated voltage 24 VDC

System description
EL290412 Version: 2.3.0
2.1.2 Bus Terminals
Mechanical data Bus Terminal
Material polycarbonate, polyamide (PA6.6).
Dimensions (W x H x D) 12mm x 100mm x 68mm or 24mm x 100mm x 68mm
Mounting on 35 mm mounting rail (EN60715) with locking
Attachable by double slot and key connection
Fig.3: TwinSAFE Terminals (EtherCAT)
Connection technology Bus Terminal
Wiring spring-loaded system
Connection cross-section 0.08 mm² ... 2.5 mm², stranded wire, solid wire
Fieldbus connection E-bus
Power contacts up to 3 blade/spring contacts
Current load 10A
Rated voltage depends on Bus Terminal type
2.1.3 E-bus
The E-bus is the data path within a terminal strip. The E-bus is led through from the Bus Coupler through all
the terminals via six contacts on the terminals' side walls.
2.1.4 Power contacts
The operating voltage is passed on to following terminals via three power contacts. Terminal strip can be
split into galvanically isolated groups by means of potential feed terminals as required. The power feed
terminals play no part in the control of the terminals, and can be inserted at any locations within the terminal
strip.

System description
EL2904 13Version: 2.3.0
2.2 TwinSAFE
2.2.1 The I/O construction kit is extended safely
With the TwinSAFE Terminals, Beckhoff offers the option of simply expanding the proven Bus Terminal
system, and to transfer the complete cabling for the safety circuit into the already existing fieldbus cable.
Safe signals can be mixed with standard signals without restriction. This saves design effort, installation and
material. Maintenance is simplified significantly through faster diagnosis and simple replacement of only a
few components.
The new ELx9xx series Bus Terminals only include three basic functionalities: digital inputs EL19xx, digital
outputs EL29xx and a logic unit EL6900. For a large number of applications, all sensors and actuators can
be wired on these Bus Terminals. The required logical link of the inputs and the outputs is handled by the
EL6900. For small to medium-sized configurations, the tasks of a fail-safe PLC can thus be handled within
the Bus Terminal system.
2.2.2 Safety concept
TwinSAFE: Safety and I/O technology in one system
• Extension of the familiar Beckhoff I/O system with TwinSAFE terminals
• Freely selectable mix of safe and standard signals
• Logical link of the I/Os in the EL6900 TwinSAFE logic terminal
• Safety-relevant networking of machines via bus systems
TwinSAFE protocol (FSoE)
• Transfer of safety-relevant data via any media (“genuine black channel”)
• TwinSAFE communication via fieldbus systems such as EtherCAT, Lightbus, PROFIBUS or Ethernet
• IEC 61508:2010 SIL 3 compliant
Configuring instead of wiring: the TwinSAFE configurator
• Configuration of the TwinSAFE system via the TwinCAT System Manager
• System Manager for editing and displaying all bus parameters
• Certified function blocks such as emergency stop, operation mode, etc.
• Simple handling
• Typical function blocks for machine safety
• any bus connection with the EL6900 TwinSAFE logic terminal
TwinSAFE logic Bus Terminal EL6900
• Link unit between TwinSAFE input and output terminals
• Configuration of a simple, flexible, cost-effective, decentralized safety controller
• No safety requirements for higher-level control system
• TwinSAFE enables networks with up to 65535 TwinSAFE devices.
• TwinSAFE Logic Terminal can establish up to 128 connections (TwinSAFE connections).
• Several TwinSAFE Logic Terminals are cascadable in a network
• Safety functions such as emergency stop, protective door, etc. are already included
• Suitable for applications up to SIL 3 according to IEC 61508:2010 and
DINENISO13849-1:2015(Cat4, PLe).

System description
EL290414 Version: 2.3.0
TwinSAFE digital input (EL1904) and output terminal (EL2904)
• All current safety sensors can be connected
• Operation with a TwinSAFE logic terminal
• EL1904 with 4 fail-safe inputs for sensors (24VDC) with potential-free contacts
• EL2904 with four safe channels for actuators (24VDC, 0.5A per channel)
• Conforming to IEC 61508:2010 SIL 3 and ENISO13849-1:2015(Cat4, PLe) requirements.
2.2.3 EL1904, EL2904 - Bus Terminals with 4 fail-safe inputs or
outputs
The EL1904 and EL2904 Bus Terminals enable connection of common safety sensors and actuators. They
are operated with the EL6900 TwinSAFE logic terminal. The TwinSAFE logic terminal is the link unit between
the TwinSAFE input and output terminals. It enables the configuration of a simple, flexible and cost-effective
decentralized safety control system.
Therefore, there are no safety requirements for the higher-level controller! The typical safety functions
required for the automation of machines, such as emergency stop, protective door, two-hand etc., are
already permanently programmed in the EL6900. The user configures the EL6900 terminal according to the
safety requirements of his application.
2.2.4 EL6900 - TwinSAFE logic terminal
The TwinSAFE Logic Terminal is the link unit between the TwinSAFE input and output terminals. The
EL6900 meets the requirements of IEC61508:2010SIL3 and ENISO13849-1:2015(Cat4, PLe).
2.2.5 The fail-safe principle (Fail Stop)
The basic rule for a safety system such as TwinSAFE is that failure of a part, a system component or the
overall system must never lead to a dangerous condition. The safe state is always the switched off and
wattless state.

Product description
EL2904 15Version: 2.3.0
3 Product description
3.1 EL2904 – TwinSAFE terminal with 4 digital fail-safe
outputs
The EL2904 is a safe output terminal with digital outputs for connecting actuators (contactors, relays, etc.)
with a maximum current 0.5A (24VDC). The Bus Terminal has 4 fail-safe outputs.
The EL2904 meets the requirements of IEC61508:2010SIL3, ENISO13849-1:2015(Cat4, PLe), NRTL,
UL508, UL1998 and UL991.
The TwinSAFE terminal has the typical design of an EtherCAT terminal.
Fig.4: EL2904 – TwinSAFE terminal with 4 digital fail-safe outputs

Product description
EL290416 Version: 2.3.0
3.2 Intended use
WARNING
Caution - Risk of injury!
TwinSAFE components shall only be used for the purposes described below!
The TwinSAFE terminals expand the application range of Beckhoff Bus Terminal system with functions that
enable them to be used for machine safety applications. The TwinSAFE terminals are designed for machine
safety functions and directly associated industrial automation tasks. They are therefore only approved for
applications with a defined fail-safe state. This safe state is the wattless state. Fail-safety according to the
relevant standards is required.
The TwinSAFE Terminals enable connection of:
• 24 VDC sensors (EL1904) such as
emergency off pushbutton switches, pull cord switches, position switches, two-hand switches, safety
mats, light curtains, light barriers, laser scanner, etc.
• 24 VDC actuators (EL2904) such as
contactors, protection door switches with tumbler, signal lamps, servo drives, etc.
Test pulses
When selecting actuators please ensure that the EL2904 test pulses do not lead to actuator switch-
ing or diagnostic message from the EL2904.
The following TwinSAFE components have been developed for these tasks:
• The EL1904 is an EtherCAT Terminal with 4 digital fail-safe inputs.
• The EL2904 is an EtherCAT Terminal with 4 digital fail-safe outputs.
• The EL6900 is an EtherCAT Terminal with integrated TwinSAFE logic.
These TwinSAFE components are suitable for operation on the
• Beckhoff EKxxxx series Bus Couplers
• Beckhoff CXxxxx series Embedded PCs with E-bus connection
WARNING
Power supply from SELV/PELV power supply unit!
The TwinSAFE components must be supplied with 24VDC by an SELV/PELV power supply unit with an out-
put voltage limit Umax of 36VDC. Failure to observe this can result in a loss of safety.
CAUTION
Follow the machinery directive!
The TwinSAFE components shall only be used in machines as defined in the machinery directive.
CAUTION
Ensure traceability!
The buyer has to ensure the traceability of the device via the serial number.
WARNING
Commissioning test
Before the EL1904/EL2904 can be used for the safety task, the user must carry out a commissioning test
so that sensor and actuator wiring errors can be ruled out.
CAUTION
Use ferrules with plastic collars
When using fine-wire cables for signal connections, use ferrules with plastic collars. This leads to a higher
system availability when the test pulses for the corresponding channels are switched off.

Product description
EL2904 17Version: 2.3.0
CAUTION
Note on approval according to EN 81-20, EN 81-22 and EN 81-50
• The TwinSAFE components shall only be used in machines that have been designed and installed in ac-
cordance with the requirements of the EN60204-1 standard.
• Provide a surge filter for the supply voltage of the TwinSAFE components against overvoltages. (Reduc-
tion to overvoltage category II)
• EN81 requires that in the case of devices with internal temperature monitoring, a stop must be reached
in the event of an overtemperature. In this case, passengers must be able to disembark (see EN81-20
chapter 5.10.4.3, for example). To ensure this, application measures are necessary. The internal termi-
nal temperature of the TwinSAFE components can be read out by the user. There is a direct switch-off at
the maximum permissible temperature of the respective TwinSAFE component (see chapter Tempera-
ture measurement).
The user must select a temperature threshold below the maximum temperature such that a stop can be
reached in all cases before the maximum temperature is reached. Information on the optimum terminal
configuration can be found under Notes on the arrangement of TwinSAFE components and under Exam-
ple configuration for temperature measurement.
• For the use of the TwinSAFE components according to EN81-22 and EN81-50, the conditions de-
scribed in the manuals for achieving category4 according to ENISO13849-1:2015 must be observed.
• The use of TwinSAFE components is limited to indoor applications.
• Basic protection against direct contact must be provided, either by fulfilling protection class IP2X or by
installing the TwinSAFE components in a control cabinet which corresponds at least to protection class
IP54 according to EN60529.
• The ambient conditions regarding temperature, humidity, heat dissipation, EMC and vibrations, as speci-
fied in the operating instructions under technical data, must be observed.
• The operating conditions in potentially explosive atmospheres (ATEX) are specified in the operating in-
structions.
• The safe state (triggering) of the application must be the de-energized state. The safe state of the Twin-
SAFE components is always the de-energized, switched-off state, and this cannot be changed.
• The service life specified in the operating instructions must be observed.
• If the TwinSAFE component is operated outside the permissible temperature range, it changes to
"Global Shutdown" state.
• The TwinSAFE components must be installed in a control cabinet with protection class IP54 according to
EN60529, so that the requirement for pollution degree3 according to EN60664-1 can be reduced to
level2.
• The TwinSAFE components must be supplied by a SELV/PELV power supply unit with a maximum volt-
age of Umax≤36VDC.

Product description
EL290418 Version: 2.3.0
3.3 Technical data
Product designation EL2904
Number of outputs 4
Status display 4 (one green LED per output)
Fault reaction time ≤ watchdog times
Output current per channel max. 500mA, min. 20mA with Current Measurement Active pa-
rameter enabled
Utilization category according to EN60947-5-1 DC-13
Intended load Pilot Duty
Actuators When selecting actuators please ensure that the EL2904 test
pulses do not lead to actuator switching.
Cable length between actuator and terminal unshielded max. 100m
shielded max. 100m
Wire cross-section min. 0.75mm2
Input process image 6bytes
Output process image 6bytes
EL2904 supply voltage (PELV) 24VDC (–15%/+20%)
(A 10A fuse should be provided for the potential group)
Protection class III
(by using a SELV/PELV power supply unit)
Overvoltage category II
Current consumption via E-bus approx. 221mA
Power dissipation of the terminal typically 2W
Electrical isolation (between the channels) no
Electrical isolation (between the channels and the E-bus) yes
Insulation voltage (between the channels and the E-bus, under com-
mon operating conditions)
Insulation tested with 500VDC
Dimensions (WxHxD) 24 mm x 100 mm x 68 mm
Weight approx.100g
Permissible ambient temperature (operation)
up to SW 03
0°C to +55°C (see notes in chapter Example configuration for
temperature measurement)
Permissible ambient temperature (operation)
from SW 04 (CW 02/2014)
-25°C to +55°C (see notes in section Example configuration for
temperature measurement)
Permissible ambient temperature (transport/storage) -40°C to +70°C
Permissible air humidity 5% to 95%, non-condensing
Permissible air pressure (operation/storage/transport) 750hPa to 1100hPa
(this corresponds to an altitude of approx. -690m to 2450m
above sea level, assuming an international standard atmos-
phere)
Climate category according to EN60721-3-3 3K3
(the deviation from 3K3 is possible only with optimal environmen-
tal conditions and also applies only to the technical data which
are specified differently in this documentation)
Permissible pollution degree
according to EN 60664-1
2
(note chapter Maintenance [}44])
Inadmissible operating conditions TwinSAFE Terminals must not be used under the following oper-
ating conditions:
• under the influence of ionizing radiation (exceeding the
natural background radiation)
• in corrosive environments
• in an environment that leads to unacceptable soiling of
the Bus Terminal
EMC immunity/emission conforms to EN61000-6-2/ EN61000-6-4
Vibration/shock resistance conforms to EN60068-2-6/ EN60068-2-27
Shocks 15g with pulse duration 11ms in all three axes
Protection class IP20
Equipment type according to EN61010-2-201 Open equipment
Permitted operating environment In the control cabinet or terminal box, with minimum protection
class IP54 according to IEC60529
Correct installation position see chapter Installation position and minimum distances
Approvals CE, cULus, ATEX, TÜV SÜD

Product description
EL2904 19Version: 2.3.0
Derating table for altitudes above 2000m
The derating table (table 8) from the IEC61131-2:2017 standard can be referred to for the use of the
TwinSAFE components above the specified maximum altitude.
Altitude in m Derating factor for the temperature1
0 to 200021.0
3000 0.9
4000 0.8
5000 0.7
Note: Linear interpolation is permissible between the altitudes
1) Ambient temperature of the device at an altitude of 2000m
2) The air pressure and air density increase as the altitude decreases. Therefore the derating factor for 0 to
2000 m (1.0) is used for altitudes below sea level.
Calculation example
In the following example the calculation is performed for a TwinSAFE component at an operating altitude of
4000m.
Permissible ambient temperature up to 2000 m above sea level = 55°C
Permissible ambient temperature up to 4000m above sea level = 55°C * 0.8 = 44°C
CAUTION
Compliance with the temperature limits
The TwinSAFE component has a maximum internal temperature at which a switch-off takes place. This is
designed for the maximum permissible ambient temperature. If the derating factor for the temperature for
higher altitudes is used, the user is solely responsible for ensuring that the calculated maximum ambient
temperature is complied with.
3.4 Safety parameters
Characteristic numbers EL2904
Lifetime [a] 20
Prooftest Interval [a] not required 1
PFHD1.25E-09
%SIL3 1.25%
PFD 8.45E-05
%SIL3 8.45%
MTTFdhigh
DC high
Performance level PL e
Category 4
HFT 1
Element classification 2Type B
1. Special proof tests are not required during the entire service life of the EL2904 EtherCAT terminal.
2. Classification according to IEC 61508-2:2010 (chapter 7.4.4.1.2 and 7.4.4.1.3)
The EL2904 EtherCAT Terminal can be used for safety-related applications within the meaning of
IEC61508:2010 up to SIL3 and ENISO13849-1:2015 up to PL e (Cat4).
For the calculation or estimation of the MTTFd value from the PFHD value, further information can be found in
the TwinSAFE Application Guide or in ISO 13849-1:2015 Table K.1.

Product description
EL290420 Version: 2.3.0
3.5 Dimensions
Fig.5: Dimensions of the EL2904
Width: 24 mm (side-by-side installation)
Height: 100 mm
Depth: 68 mm