Beckhoff KL6904 User manual

Operating Instructions | EN
KL6904
TwinSAFE logic terminal with 4 fail-safe outputs
2023-03-20 | Version: 3.0.0

Table of contents
KL6904 3Version: 3.0.0
Table of contents
1 Notes on the documentation....................................................................................................................5
1.1 Disclaimer..........................................................................................................................................5
1.1.1 Trademarks ........................................................................................................................5
1.1.2 Patents ...............................................................................................................................5
1.1.3 Limitation of liability ............................................................................................................6
1.1.4 Copyright............................................................................................................................ 6
1.2 Documentation issue status ..............................................................................................................7
1.3 Staff qualification...............................................................................................................................8
1.4 Safety and instruction........................................................................................................................9
1.4.1 Explanation of symbols ...................................................................................................... 9
1.5 Beckhoff Support and Service.........................................................................................................10
2 For your safety ........................................................................................................................................11
2.1 Duty of care.....................................................................................................................................11
2.2 Safety image signs..........................................................................................................................12
2.3 General safety instructions..............................................................................................................13
2.3.1 Before operation............................................................................................................... 13
2.3.2 In operation ...................................................................................................................... 13
2.3.3 After operation.................................................................................................................. 13
3 System description .................................................................................................................................14
3.1 The Beckhoff Bus Terminal system ................................................................................................14
3.1.1 Bus Coupler ..................................................................................................................... 15
3.1.2 Bus Terminals .................................................................................................................. 16
3.1.3 K-bus................................................................................................................................ 17
3.1.4 Power contacts................................................................................................................. 17
3.2 TwinSAFE .......................................................................................................................................18
3.2.1 The I/O construction kit is extended safely ...................................................................... 18
3.2.2 Safety concept ................................................................................................................. 18
3.2.3 KL1904, KL2904 - Bus Terminals with 4 fail-safe inputs or outputs................................. 19
3.2.4 KL6904 - TwinSAFE logic terminal with 4 fail-safe outputs.............................................. 19
3.2.5 The fail-safe principle (Fail Stop) ..................................................................................... 19
4 Product description ................................................................................................................................20
4.1 KL6904 – TwinSAFE terminal with 4 fail-safe outputs ....................................................................20
4.2 Intended use ...................................................................................................................................21
4.3 Technical data.................................................................................................................................22
4.4 Safety parameters...........................................................................................................................23
4.5 Dimensions .....................................................................................................................................23
5 Operation .................................................................................................................................................24
5.1 Environmental conditions ................................................................................................................24
5.2 Installation .......................................................................................................................................24
5.2.1 Safety instructions............................................................................................................ 24
5.2.2 Transport / storage........................................................................................................... 24
5.2.3 Mechanical installation .....................................................................................................24
5.2.4 Electrical installation......................................................................................................... 26

Table of contents
KL69044 Version: 3.0.0
5.3 Configuration of the terminal in TwinCAT .......................................................................................30
5.3.1 Configuration requirements.............................................................................................. 30
5.3.2 Inserting a Bus Coupler.................................................................................................... 30
5.3.3 Inserting a Bus Terminal .................................................................................................. 30
5.3.4 Inserting a KL6904 ........................................................................................................... 31
5.3.5 Address settings on TwinSAFE terminals with 1023 possible addresses........................ 33
5.3.6 Creating a TwinSAFE group ............................................................................................ 33
5.3.7 TwinSAFE group signals.................................................................................................. 36
5.3.8 Append a function block................................................................................................... 37
5.3.9 KL6904 user and version administration.......................................................................... 42
5.3.10 Loading the project into the KL6904 ................................................................................43
5.3.11 Communication between TwinCAT controllers ................................................................45
6 Diagnosis .................................................................................................................................................49
6.1 Diagnosis LEDs...............................................................................................................................49
6.1.1 Diag1 (green) ................................................................................................................... 49
6.1.2 Diag2 (red) ....................................................................................................................... 49
6.1.3 Diag3 (red) and Diag4 (red) ............................................................................................. 50
7 Service life ...............................................................................................................................................51
8 Maintenance and cleaning .....................................................................................................................52
9 Decommissioning ...................................................................................................................................53
9.1 Disposal ..........................................................................................................................................53
9.1.1 Returning to the vendor.................................................................................................... 53
10 Appendix..................................................................................................................................................54
10.1 Volatility...........................................................................................................................................54
10.2 Focus of certificates ........................................................................................................................55
10.3 Certificate ........................................................................................................................................56

Notes on the documentation
KL6904 5Version: 3.0.0
1 Notes on the documentation
1.1 Disclaimer
Beckhoff products are subject to continuous further development. We reserve the right to revise the
operating instructions 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 these
operating instructions.
In these operating instructions we define all permissible use cases whose properties and operating
conditions we can guarantee. The use cases we define are fully tested and certified. Use cases beyond this,
which are not described in these operating instructions, require the approval of Beckhoff Automation GmbH
& Co KG.
1.1.1 Trademarks
Beckhoff®, TwinCAT®, EtherCAT®, EtherCAT G®, EtherCAT G10®, EtherCAT P®, Safety over EtherCAT®,
TwinSAFE®, XFC®, XTS® and XPlanar® are registered and licensed trademarks of Beckhoff Automation
GmbH.
The use of other brand names or designations by third parties may lead to an infringement of the rights of
the owners of the corresponding designations.
1.1.2 Patents
The EtherCAT technology is protected by patent rights through the following registrations and patents with
corresponding applications and registrations in various other countries:
• EP1590927
• EP1789857
• EP1456722
• EP2137893
• DE102015105702
EtherCAT® is a registered trademark and patented technology,
licensed by Beckhoff Automation GmbH.
Safety over EtherCAT® is a registered trademark and patented
technology, licensed by Beckhoff Automation GmbH.

Notes on the documentation
KL69046 Version: 3.0.0
1.1.3 Limitation of liability
All components in this product as described in the operating instructions are delivered in a specific
configuration of hardware and software, depending on the application regulations. Modifications and
changes to the hardware and/or software configuration that go beyond the documented options are
prohibited and nullify the liability of Beckhoff Automation GmbH & Co. KG.
The following is excluded from the liability:
• Failure to observe these operating instructions
• Improper use
• Use of untrained personnel
• Use of unauthorized spare parts
1.1.4 Copyright
© Beckhoff Automation GmbH & Co. KG, Germany.
The distribution and reproduction of this document as well as the use and communication of its contents
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.

Notes on the documentation
KL6904 7Version: 3.0.0
1.2 Documentation issue status
Version Comment
3.0.0 • Migration
• Foreword changed to Notes on the documentation [}5] and For your safety [}11]
• In chapter Technical data [}22] link to download page of certificates added
•Maintenance and cleaning [}52] and Decommissioning [}53] added
• Appendix adapted and extended
2.2.1 • Technical data permissible air pressure expanded
2.2.0 • Reliability document updated
• Safety parameters updated
• Foreword overworked
2.1.2 • Reliability document updated
2.1.1 • Certificate updated
2.1.0 • Company address amended
• Document origin added
• Version history added
• EN954 example removed
• Safety parameters extended
2.0.1 • Reference to EN 60068-2-29 removed
2.0.0 • Description of the configuration in the TwinCAT System Manager added
• Certificates added
• Note on test pulses of the outputs added
• Tested devices extended
1.1.4 • Diagrams corrected
• Flash codes corrected
1.1.3 • Pin assignment corrected
1.1.2 • Technical data updated
1.1.1 • LED and graphics updated
1.1.0 • Technical data extended
• Editorial amendments
1.0.3 • Description of LEDs and blink codes updated
• TwinSAFE description updated
1.0.2 • Note relating to qualified software tool amended
1.0.1 • LoP list incorporated
1.0.0 • First publication
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 http://www.beckhoff.de/twinsafe. In case of doubt, please
contact Technical Support (see Beckhoff Support and Service [}10]).
Origin of the document
The original documentation is written in German. All other languages are derived from the German original.
Product features
Only the product properties specified in the current operating instructions are valid. Further information given
on the product pages of the Beckhoff homepage, in emails or in other publications is not authoritative.

Notes on the documentation
KL69048 Version: 3.0.0
1.3 Staff qualification
These operating instructions are intended exclusively for trained specialists in control technology and
automation with the relevant knowledge.
The trained specialist personnel must ensure that the applications and use of the described product meet all
safety requirements. This includes all applicable and valid laws, regulations, provisions and standards.
Trained specialists
Trained specialists have extensive technical knowledge from studies, apprenticeships or technical training.
Understanding of control technology and automation is available. Trained specialists can:
• Independently identify, avoid and eliminate sources of hazard.
• Apply relevant standards and directives.
• Implement specifications from accident prevention regulations.
• Evaluate, prepare and set up the workplaces.
• Evaluate, optimize and execute work independently.

Notes on the documentation
KL6904 9Version: 3.0.0
1.4 Safety and instruction
Read the contents that refer to the activities you have to perform with the product. Always read the chapter
For your safety [}11] in the operating instructions.
Observe the warnings in the chapters so that you can handle and work with the product as intended and
safely.
1.4.1 Explanation of symbols
Various symbols are used for a clear arrangement:
1. The numbering indicates an action that should be taken.
• The bullet point indicates an enumeration.
[…] The square brackets indicate cross-references to other text passages in the document.
[1] The number in square brackets indicates the numbering of a referenced document.
1.4.1.1 Pictograms
In order to make it easier for you to find text passages, pictograms and signal words are used in warning
notices:
DANGER
Failure to observe will result in serious or fatal injuries.
WARNING
Failure to observe may result in serious or fatal injuries.
CAUTION
Failure to observe may result in minor or moderate injuries.
NOTE
Notes
Notes are used for important information on the product. The possible consequences of failure to observe
these include:
• Malfunctions of the product
• Damage to the product
• Damage to the environment
Information
This sign indicates information, tips and notes for dealing with the product or the software.

Notes on the documentation
KL690410 Version: 3.0.0
1.5 Beckhoff Support and Service
Support
Beckhoff Support offers technical advice on the use of individual Beckhoff products and system planning.
The employees support you in the programming and commissioning of sophisticated automation systems.
Hotline: [phone]
E-mail: [email protected]
Web: www.beckhoff.com/support
Training
Training in Germany takes place in our training center at the Beckhoff headquarters in Verl, at subsidiaries
or, by arrangement, at the customer's premises.
Hotline: [phone]
E-mail: [email protected]
Web: www.beckhoff.com/training
Service
The Beckhoff Service Center supports you with after-sales services such as on-site service, repair service or
spare parts service.
Hotline: [phone]
E-mail: [email protected]
Web: www.beckhoff.com/service
Download area
In the download area you can obtain product information, software updates, the TwinCAT automation
software, documentation and much more.
Web: www.beckhoff.com/download
Headquarters
Beckhoff Automation GmbH & Co. KG
Hülshorstweg 20
33415 Verl
Germany
Phone: [phone]
E-mail: [email protected]
Web: www.beckhoff.com
For the addresses of our worldwide locations, please visit our website at Global Presence.

For your safety
KL6904 11Version: 3.0.0
2 For your safety
Read this chapter containing general safety information. In addition, always observe the safety instructions
and warnings in these operating instructions for your own safety, the safety of other persons and the safety
of the product.
When working with control and automation products, many dangers can result from careless or incorrect use.
Work particularly thoroughly, not under time pressure and responsibly towards other people.
2.1 Duty of care
Read entire documentation for TwinSAFE component
• TwinSAFE application manual
• EL6910 TwinSAFE logic terminal operating manual
• TwinSAFE Logic FB documentation manual
The operator must comply with all the requirements and notes specified in these operating instructions in
order to fulfill his duty of care. This includes in particular that you
• comply with the provisions defined in the chapter Limitation of liability [}6].
• only operate the TwinSAFE component when it is in perfect working order.
• provide the operating instructions in a legible condition and complete at the place of use of the
TwinSAFE component.
• do not remove the safety markings attached to the TwinSAFE component and maintain their legibility.
No disposal in domestic waste
Products marked with a crossed-out waste bin must not be disposed of with domestic
waste. The device is considered waste electrical and electronic equipment when it is
disposed of. Observe the national regulations for the disposal of waste electrical and
electronic equipment.

For your safety
KL690412 Version: 3.0.0
2.2 Safety image signs
On Beckhoff products you will find attached or lasered safety pictograms, which vary depending on the
product. They serve to serve to ensure safety for people and to prevent damage to the products. Safety
pictograms must not be removed and must be legible for the user.
Read and observe the operating instructions
Commissioning is only permitted if the operating instructions have been read and understood
beforehand. This applies in particular to the safety instructions and warnings.
Electrostatic sensitive components
Work with and on the TwinSAFE component is only permitted in protected workplaces.

For your safety
KL6904 13Version: 3.0.0
2.3 General safety instructions
2.3.1 Before operation
Use in machines according to the Machinery Directive
Only use the TwinSAFE component in machines that comply with the Machinery Directive. This is how you
ensure safe operation.
Ensure traceability
Ensure the traceability of the TwinSAFE component via the serial number.
Carry out commissioning test
Before commissioning, wiring faults to the sensors must be excluded. Before commissioning, carry out a
commissioning test. After a successful commissioning test, you can use the TwinSAFE component for the
intended safety-related task.
In case of wiring errors, the safety function of the product is at risk. Depending on the machine, death and
danger to life, serious bodily injury and damage to the machine may result.
2.3.2 In operation
Interference due to emitted interference
Do not operate the following devices in the vicinity of the TwinSAFE component: for example, radio
telephones, radios, transmitters or high-frequency systems.
TwinSAFE components comply with the requirements of the applicable electromagnetic compatibility
standards with regard to interference emission and immunity. If you exceed the limits for emitted interference
specified in the standards, the function of the TwinSAFE component may be impaired.
2.3.3 After operation
De-energize and switch off components before working on them
Check all safety-relevant equipment for functionality before working on the TwinSAFE component. Secure
the working environment. Secure the machine or plant against being inadvertently started up. Observe the
chapter Decommissioning [}53].

System description
KL690414 Version: 3.0.0
3 System description
3.1 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 terminals via the screwless Cage Clamp© connection system.
Fig.1: Slot and key system and screwless (spring-loaded) connection system.
Since a wide range of different communication standards are established in industrial automation, Beckhoff
offers Bus Couplers for all common bus systems (e.g. BK3120 for PROFIBUS, BK9000 for Ethernet, etc.).

System description
KL6904 15Version: 3.0.0
3.1.1 Bus Coupler
Mechanical data Bus Coupler
Material polycarbonate, polyamide (PA6.6).
Dimensions (W x H x D) 47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
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
KL690416 Version: 3.0.0
3.1.2 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
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 depending on fieldbus
Power contacts up to 3 blade/spring contacts
Current load 10A
Rated voltage depends on Bus Terminal type

System description
KL6904 17Version: 3.0.0
3.1.3 K-bus
The K-Bus is the data path within a terminal strip. The K-Bus is led through from the Bus Coupler through all
the terminals via six contacts on the terminals' side walls. The end terminal terminates the K-Bus.
3.1.4 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
KL690418 Version: 3.0.0
3.2 TwinSAFE
3.2.1 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 KLx9xx series Bus Terminals only include three basic functionalities: digital KL19xx inputs, digital
KL29xx outputs and a KL6904 link unit. 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
KL6904. For small to medium-sized configurations, the tasks of a fail-safe PLC can thus be handled within
the Bus Terminal system.
3.2.2 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
• Logic link of the I/Os in the KL6904 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
• Freely selectable fieldbus connection with the KL6904 TwinSAFE logic terminal
KL6904 TwinSAFE logic Bus Terminal
• 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 1023 TwinSAFE devices.
• TwinSAFE logic terminal can establish up to 15 connections (TwinSAFE connections).
• Several TwinSAFE Logic Terminals are cascadable in a network
• Safety functions such as emergency stop, protective door, etc. are already included
• Safe outputs integrated
• Suitable for applications up to SIL 3 according to IEC 61508:2010

System description
KL6904 19Version: 3.0.0
TwinSAFE digital input (KL1904) and output terminal (KL2904)
• All current safety sensors can be connected
• Operation with a TwinSAFE logic terminal
• KL1904 with 4 fail-safe inputs for sensors (24VDC) with floating contacts
• KL2904 with 4 safe channels for actuators (24VDC, 0.5A per channel)
• Conforming to IEC 61508:2010 SIL 3
3.2.3 KL1904, KL2904 - Bus Terminals with 4 fail-safe inputs or
outputs
The KL1904 and KL2904 Bus Terminals enable connection of common safety sensors and actuators. They
are operated with the KL6904 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 KL6904. The user configures the KL6904 terminal according to the
safety requirements of his application.
3.2.4 KL6904 - TwinSAFE logic terminal with 4 fail-safe outputs
The KL6904 TwinSAFE logic terminal is a digital output terminal with four fail-safe outputs with 0.5 A, 24
VDC. The KL6904 meets the requirements of IEC 61508:2010 SIL 3 and DIN EN ISO 13849-1:2006 (Cat 4,
PL e).
3.2.5 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
KL690420 Version: 3.0.0
4 Product description
4.1 KL6904 – TwinSAFE terminal with 4 fail-safe outputs
KL6904 TwinSAFE logic terminal with four fail-safe outputs
The KL6904 is a safe small controller 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 KL6904 meets the requirements of IEC 61508:2010 SIL 3, DIN EN ISO 13849-1:2006 (Cat 4, PL e),
NRTL, UL508, UL1998 and UL991.
The Bus Terminal has the standard design of a Beckhoff Bus Terminal.
Fig.4: KL6904