Beckhoff EL2904 User manual

Operating instructions for
EL2904
TwinSAFE output terminal with 4 fail-safe outputs
Version: 1.2.0
Date: 2012-03-06

Table of contents
EL2904 1
Table of contents
1Foreword 3
1.1 Notes on the manual 3
1.1.1 Disclaimer 3
1.1.2 Trademarks 3
1.1.3 Patent Pending 3
1.1.4 Copyright 3
1.1.5 Delivery conditions 3
1.2 Safety instructions 4
1.2.1 Delivery state 4
1.2.2 Operator's obligation to exercise diligence 4
1.2.3 Description of safety symbols 5
2System description 6
2.1 The Beckhoff Bus Terminal system 6
2.1.1 Bus Coupler 7
2.1.2 Bus Terminals 8
2.1.3 E-bus 8
2.1.4 Power contacts 8
2.2 TwinSAFE 9
2.2.1 The I/O construction kit is extended safely 9
2.2.2 Safety concept 9
2.2.3 EL1904, EL2904 – Bus Terminals with 4 fail-safe inputs or outputs 10
2.2.4 EL6900 - TwinSAFE logic terminal 10
2.2.5 The fail-safe principle (Fail Stop) 10
3Product description 11
3.1 General description 11
3.2 Appropriate use 12
3.3 Technical data 13
3.4 Dimensions 14
4Operation 15
4.1 Installation 15
4.1.1 Safety instructions 15
4.1.2 Transport / storage 15
4.1.3 Mechanical installation 16
4.1.4 Electrical installation 18
4.1.5 Tested devices 22

Table of contents
2EL2904
4.2 Operation in potentially explosive atmospheres (ATEX) 23
4.2.1 Special conditions 23
4.2.2 Identification 24
4.2.3 Date code and serial number 24
4.2.4 Further ATEX documentation 24
4.3 Configuration of the EL2904 in the TwinCAT System Manager 25
4.3.1 Inserting a Beckhoff Bus Coupler 25
4.3.2 Inserting a Beckhoff Bus Terminal 25
4.3.3 Inserting an EL2904 25
4.3.4 Address settings on the TwinSAFE terminals 26
4.3.5 Entering a TwinSAFE address and parameters in the System Manager 27
4.4 Diagnostics 29
4.4.1 Diagnostic LEDs 29
4.4.2 Diagnostic objects 32
4.5 Maintenance 33
4.5.1 Cleaning 33
4.6 Service life 33
4.6.1 Shutting down 33
4.6.2 Disposal 33
5Appendix 34
5.1 Beckhoff Support and Service 34
5.1.1 Beckhoff branches and partner companies Beckhoff Support 34
5.1.2 Beckhoff company headquarters 34
5.2 Certificates 35

Foreword
EL2904 3
1 Foreword
1.1 Notes on the manual
This description is only intended for the use of trained specialists in control and automation technology
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.
1.1.1 Disclaimer
The documentation has been prepared with care. The products described are, however, constantly under
development. For that reason the documentation is not in every case checked for consistency with
performance data, standards or other characteristics.
In the event that it contains technical or editorial errors, we retain the right to make alterations at any time
and without warning.
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.
1.1.2 Trademarks
Beckhoff®, TwinCAT®, EtherCAT®, Safety over EtherCAT®, TwinSAFE®and XFC®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.
1.1.3 Patent Pending
The EtherCAT Technology is covered, including but not limited to the following patent applications and
patents: EP1590927, EP1789857, DE102004044764, DE102007017835 with corresponding applications
or registrations in various other countries.
The TwinCAT Technology is covered, including but not limited to the following patent applications and
patents: EP0851348, US6167425 with corresponding applications or registrations in various other
countries.
1.1.4 Copyright
©Beckhoff Automation GmbH.
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.
1.1.5 Delivery conditions
In addition, the general delivery conditions of the company Beckhoff Automation GmbH apply.

Foreword
4EL2904
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.
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 manual and in particular the safety notes
contained herein.
the instruction manual is 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 5
1.2.3 Description of safety symbols
The following safety symbols are used in this operating manual. They are intended to alert the reader to
the associated safety instructions.
Serious risk of injury!
DANGER Failure to follow the safety instructions associated with this symbol directly endangers
the life and health of persons.
Caution – Risk of injury!
WARNING Failure to follow the safety instructions associated with this symbol endangers the life
and health of persons.
Personal injuries!
CAUTION Failure to follow the safety instructions associated with this symbol can lead to injuries
to persons.
Damage to the environment or devices
Warning Failure to follow the instructions associated with this symbol can lead to damage to the
environment or equipment.
Tip or pointer
Note This symbol indicates information that contributes to better understanding.

System description
6EL2904
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 50022). 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 terminals via the screwless Cage Clamp©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 7
2.1.1 Bus Coupler
Mechanical data
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 (EN50022) with lock
Attachable by double slot and key connection
Connection technology
Connection technology Bus Coupler
Wiring Cage Clamp®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
8EL2904
2.1.2 Bus Terminals
Mechanical data
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 (EN50022) with lock
Attachable by double slot and key connection
Connection technology
Connection technology Bus Terminal
Wiring Cage Clamp®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 9
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 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 and DIN EN ISO 13849-
1:2006 (Cat 4, PL e).

System description
10 EL2904
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 floating contacts
EL2904 with four safe channels for actuators (24 VDC, 0.5 A per channel)
conforming to IEC 61508 SIL 3 and DIN EN ISO 13849-1:2006 (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 SIL 3, EN 954 Cat. 4 and DIN EN ISO 13849-1:2006 (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 11
3 Product description
3.1 General description
EL2904 - Digital four-channel TwinSAFE output terminal
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 SIL 3, EN 954 Cat 4,
DIN EN ISO 13849-1:2006 (Cat 4, PL e), NRTL, UL508, UL1998 and UL991.
The TwinSAFE terminal has the typical design of an EtherCAT terminal.

Product description
12 EL2904
3.2 Appropriate use
Caution – Risk of injury!
WARNING TwinSAFE terminals may 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 stop push buttons, pull cord switches, position switches, two-hand switches, safety
mats, light curtains, light barriers, laser scanners etc.
24 VDC actuators (EL2904) such as
contactors, protective door switches with tumbler, signal lamps, servo drives etc.
Test pulses
Note When selecting actuators please ensure that the EL2904 test pulses do not
lead to actuator switching or diagnostic message from the EL2904.
The following modules were developed for these tasks:
The EL1904 terminal is an input module with digital inputs.
The EL2904 terminal is an output module with digital outputs.
The EL6900 terminal is a logic module.
These modules are suitable for operation with
Beckhoff EKxxxx series Bus Couplers
Beckhoff CXxxxx series Embedded PCs with E-bus connection
Follow the machinery directive
CAUTION The TwinSAFE terminals may only be used in machines according to the Machinery
Directive.
Ensure traceability
CAUTION The buyer has to ensure the traceability of the device via the serial number.

Product description
EL2904 13
3.3 Technical data
Product name EL2904
Number of inputs 0
Number of outputs 4
Status display 4 (one green LED per output)
Fault response time watchdog times
Output current per channel max. 500 mA, min. 20 mA with current measurement
active
Actuators When selecting actuators please ensure that the
EL2904 test pulses do not lead to actuator
switching.
(unshielded) max. 100 mCable length between
actuator and terminal (shielded) max. 100 m
Wire cross section min. 0.75 mm2
Input process image 6 bytes
Output process image 6 bytes
EL2904 supply voltage 24 VDC (–15%/+20%)
Current consumption from the E-bus approx. 221 mA
Power dissipation of the terminal typically 2 W
Electrical isolation (between the channels) no
Electrical isolation (between the channels/E-bus) yes
Insulation voltage (between the channels and the
E-bus, under common operating conditions) insulation tested with 500 VDC
Dimensions (W x H x D) 24mm x 100mm x 68mm
Weight approx. 100 g
Permissible ambient temperature (operation) 0°C to +55°C
Permissible ambient temperature
(transport/storage) -25°C to +70°C
Permissible air humidity 5% to 95%, non-condensing
Permissible air pressure
(operation/storage/transport) 750 hPa to 1100 hPa
Climate class according to EN 60721-3-3 3K3
Permissible contamination level Contamination level 2
(follow the chapter cleaning)
Unacceptable operating conditions TwinSAFE terminals must not be used under the
following operating conditions:
under the influence of ionizing 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,
EN 60068-2-29
Shocks 15 g with pulse duration 11 ms in all three axes
Protection class IP20
Permitted operating environment control cabinet or terminal box with minimum
protection class IP54 according to IEC 60529
Permissible installation position see chapter
Installation position and minimum distances
Approvals CE, cULus, ATEX

Product description
14 EL2904
3.4 Dimensions
Width: 24 mm (side-by-side installation)
Height: 100 mm
Depth: 68 mm

Operation
EL2904 15
4 Operation
Please ensure that the TwinSAFE terminals are only transported, stored and operated under the specified
conditions (see technical data)!
Caution – Risk of injury!
WARNING The TwinSAFE terminals must not be used under the following operating conditions:
under the influence of ionizing radiation
in corrosive environments
in an environment that leads to unacceptable soiling of the Bus Terminal
4.1 Installation
4.1.1 Safety instructions
Before installing and commissioning the TwinSAFE terminals please read the safety notes in the foreword
of this documentation.
4.1.2 Transport / storage
Use the original packaging for transporting or storing the digital TwinSAFE terminals.
Note the specified environmental conditions
CAUTION Please ensure that the digital TwinSAFE terminals are only transported and stored
under the specified environmental conditions (see technical data).

Operation
16 EL2904
4.1.3 Mechanical installation
Serious risk of injury!
DANGER Bring the bus system into a safe, de-energized state before starting installation,
disassembly or wiring of the Bus Terminals!
4.1.3.1 Control cabinet
The TwinSAFE terminals must be installed in a control cabinet or terminal box with IP54 protection class
according to IEC 60529 as a minimum.
4.1.3.2 Installation position and minimum distances
For the prescribed installation position the mounting rail is installed horizontally and the mating surfaces
of the EL/KL terminals point toward the front (see illustration below). The terminals are ventilated from
below, which enables optimum cooling of the electronics through convection. The direction indication
“down” corresponds to the direction of positive acceleration due to gravity.
In order to ensure optimum convection cooling, the distances to neighbouring devices and to control
cabinet walls must not be smaller than those shown in the diagram.

Operation
EL2904 17
4.1.3.3 Mounting rail installation
Mounting
The Bus Couplers and Bus Terminals are attached to commercially available 35 mm mounting rails
(according to EN 50022) by applying slight pressure:
1. First attach the Fieldbus Coupler to the mounting rail.
2. The Bus Terminals are now attached on the right-hand side of the fieldbus Coupler. Join the
components with slot and key and push the terminals against the mounting rail, until the lock
clicks onto the mounting rail.
If the terminals are clipped onto the mounting rail first and then pushed together without slot
and key, the connection will not be operational! When correctly assembled, no significant gap
should be visible between the housings.
3. During the installation of the Bus Terminals, the locking mechanism of the terminals must not
come into conflict with the fixing bolts of the mounting rail.

Operation
18 EL2904
Removal
1. Carefully pull the orange-colored lugs approximately 1 cm out of the disassembled terminal, until
they protrude loosely. The lock with the mounting rail is now released for this terminal, and the
terminal can be pulled from the mounting rail without excessive force.
2. Grasp the released terminal with thumb and index finger simultaneous at the upper and lower
grooved housing surfaces and pull the terminal away from the mounting rail.
4.1.4 Electrical installation
4.1.4.1 Connections within a Bus Terminal block
The electric connections between the Bus Coupler and the Bus Terminals are automatically realised by
joining the components:
The six spring contacts of the E-bus deal with the transfer of the data and the supply of the Bus
Terminal electronics.
Note the maximum E-bus current!
Note Observe the maximum current that your Bus Coupler can supply to the E-bus!
Use the EL9400 Power Supply Terminal if the current consumption of your
terminals exceeds the maximum current that your Bus Coupler can feed to the
E-bus supply.
The power contacts deal with the supply for the field electronics and thus represent a supply rail
within the Bus Terminal block. The power contacts are supplied via terminals on the Bus Coupler.
Note the pin assignment of the power contacts!
Note During the design of a Bus Terminal block, the pin assignment of the individual
Bus Terminals must be taken account of, since some types (e.g. analog Bus
Terminals or digital 4-channel Bus Terminals) do not or not fully loop through the
power contacts.
Power Feed Terminals (EL91xx, EL92xx) interrupt the power contacts and thus
represent the start of a new supply rail.