Beckhoff KL6904 User manual

Operating instructions for
KL6904
TwinSAFE logic terminal with 4 fail-safe outputs
Version: 2.0.0
Date: 21.10.2008

Table of contents
KL6904 1
Table of contents
1Foreword 3
1.1 Notes on the manual 3
1.1.1 Liability conditions 3
1.1.2 Delivery conditions 3
1.1.3 Copyright 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 4
2System description 5
2.1 The Beckhoff Bus Terminal system 5
2.1.1 Bus Coupler 6
2.1.2 Bus Terminals 7
2.1.3 K-bus 7
2.1.4 Power contacts 7
2.2 TwinSAFE 8
2.2.1 The I/O construction kit is extended safely 8
2.2.2 Safety concept 8
2.2.3 KL1904, KL2904 – Bus Terminals with 4 fail-safe inputs or outputs 9
2.2.4 KL6904 TwinSAFE logic terminal with 4 fail-safe outputs 9
2.2.5 The fail-safe principle (Fail Stop) 9
3Product description 10
3.1 General description 10
3.2 Appropriate use 11
3.3 Technical data 12
3.4 Dimensions 13

Table of contents
2KL6904
4Operation 14
4.1 Installation 14
4.1.1 Safety instructions 14
4.1.2 Transport / storage 14
4.1.3 Mechanical installation 15
4.1.4 Electrical installation 16
4.1.5 Tested devices 22
4.2 Configuration of the KL6904 in the TwinCAT System Manager 23
4.2.1 Configuration requirements 23
4.2.2 Inserting a Beckhoff Bus Coupler 23
4.2.3 Inserting a Beckhoff Bus Terminal 23
4.2.4 Inserting a KL6904 23
4.2.5 Address settings on the TwinSAFE terminals 25
4.2.6 Entering the TwinSAFE addresses in the System Manager 26
4.2.7 Creating a TwinSAFE Group 27
4.2.8 Add a function block 30
4.2.9 KL6904 user and version administration 36
4.2.10 Loading the project into the KL6904 37
4.2.11 Communication between TwinCAT controllers 39
4.3 Diagnostics 43
4.3.1 Diagnostic LEDs 43
4.4 Maintenance 46
4.4.1 Cleaning 46
4.5 Service life 46
4.5.1 Shutting down 46
4.5.2 Disposal 46
5Appendix 47
5.1 Beckhoff Support and Service 47
5.2 Beckhoff company headquarters 47
5.3 Certificates 48

Foreword
KL6904 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.
1.1.1 Liability conditions
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.
The documentation has been prepared with care. The products described are, however, constantly under
development. For this reason, the documentation may not always be have been fully checked for
consistency with the performance data, standards or other characteristics described. None of the
statements in this manual represent a guarantee for as set out in § 443 of the German Civil Code or a
statement about the assumed use according to the contract as set out in § 434 para. 1 clause 1 no. 1 of
the German Civil Code. 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 Delivery conditions
In addition, the general delivery conditions of the company Beckhoff Automation GmbH apply.
1.1.3 Copyright
©This manual is subject to copyright. Any reproduction or third party use of this publication, whether in
whole or in part, without the written permission of Beckhoff Automation GmbH, is forbidden.

Foreword
4KL6904
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 product description chapter);
•the TwinSAFE products are only operated in sound condition and in working order.
•the TwinSAFE products are operated only by suitably qualified and authorised 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.
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.
Danger for persons, the environment or equipment
CAUTION Failure to follow the safety instructions associated with this symbol may endanger
persons, the environment or equipment.
Tip or pointer
Note This symbol indicates information that contributes to better understanding.

System description
KL6904 5
2 System description
2.1 The Beckhoff Bus Terminal system
The Beckhoff Bus Terminal system is used for decentralised 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.
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
6KL6904
2.1.1 Bus Coupler
Mechanical data
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 (EN50022) with lock
Attachable by double slot and key connection
Connection
Connection 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
Nominal voltage 24 VDC

System description
KL6904 7
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
Connection 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
Nominal voltage depends on Bus Terminal type
2.1.3 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.
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
8KL6904
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 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.
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
•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 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, decentralised 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 and EN 954 Cat. 4

System description
KL6904 9
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 four safe channels for actuators (24 VDC, 0.5 A per channel)
•Compliant with IEC 61508 SIL 3 and EN 954 Cat. 4
2.2.3 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 decentralised 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.
2.2.4 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 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
10 KL6904
3 Product description
3.1 General description
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 SIL 3 and EN 954 Cat. 4,
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.

Product description
KL6904 11
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 (KL1904) 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 (KL2904, KL6904) such as
contactors, protection door switches with tumbler, signal lamps, servo drives etc.
Test pulses
Note When selecting actuators please ensure that the KL6904 test pulses do not
lead to actuator switching or diagnostic message from the KL6904.
The test pulses of the KL6904 terminal outputs are not configurable and cannot
be switched off.
The following modules were developed for these tasks:
•The KL1904 terminal is an input module with digital inputs.
•The KL2904 terminal is an output module with digital outputs.
•The KL6904 terminal is a logic module with digital outputs.
These modules are suitable for operation with
•Beckhoff BKxxxx series Bus Couplers
•Beckhoff BXxxxx series Bus Terminal Controllers (with firmware version ≥1.20)
(Beckhoff BCxxxx series Bus Terminal Controllers are not supported!)
•Beckhoff CXxxxx series Embedded PCs with K-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
12 KL6904
3.3 Technical data
Product name KL6904
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
Actuators When selecting actuators please ensure that the
output test pulses do not lead to actuator switching.
(unscreened) max. 100 mCable length between
actuator and terminal (screened) max. 100 m
Wire cross section min. 0.75 mm2
Input process image 192 byte max.
Output process image 192 byte max.
KL6904 supply voltage 24 VDC (-15%/+20%)
Current consumption from K-bus maximum 250 mA
Power dissipation of the terminal typically 2 W
Electrical isolation (between the channels) no
Electrical isolation (between the channels and the
K-Bus) yes
Insulation voltage (between the channels and the
K-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
(please see the section on cleaning)
Unacceptable operating conditions TwinSAFE terminals must not be used under the
following operating conditions:
•under the influence of ionising radiation
•in corrosive environments
•in an environment that leads to
unacceptable soiling of the Bus Terminal
Vibration / shock resistance conforms to EN 60068-2-6 / EN 60068-2-27,
EN 60068-2-29
EMC resistance burst / ESD conforms to EN 61000-6-2 / EN 61000-6-4
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 horizontal
Approvals CE

Product description
KL6904 13
3.4 Dimensions
Width: 24 mm (side-by-side installation)
Height: 100 mm
Depth: 68 mm

Operation
14 KL6904
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 ionising 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
KL6904 15
4.1.3 Mechanical installation
Serious risk of injury!
DANGER Bring the bus system into a safe, de-energised 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 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
16 KL6904
Removal
1. Carefully pull the orange-coloured 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 K-Bus deal with the transfer of the data and the supply of the Bus
Terminal electronics.
Note the maximum K-Bus current!
Note Observe the maximum current that your Bus Coupler can supply to the K-Bus!
Use the KL9400 Power Supply Terminal if the current consumption of your
terminals exceeds the maximum current that your Bus Coupler can feed to the
K-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 (KL91xx, KL92xx) interrupt the power contacts and thus
represent the start of a new supply rail.

Operation
KL6904 17
PE power contact
The power contact labelled PE can be used as a protective earth. For safety reasons this contact mates
first when plugging together, and can ground short-circuit currents of up to 125 A.
Insulation tests
CAUTION Note that, for reasons of electromagnetic compatibility, the PE contacts are
capacitatively coupled to the mounting rail. This may lead to incorrect results during
insulation testing or to damage on the terminal (e.g. disruptive discharge to the PE line
during insulation testing of a consumer with a nominal voltage of 230 V).
For insulation testing, disconnect the PE supply line at the Bus Coupler or the Power
Feed Terminal! In order to decouple further feed points for testing, these Power Feed
Terminals can be released and pulled at least 10 mm from the group of terminals.
Serious risk of injury!
DANGER The PE power contact must not be used for other potentials!

Operation
18 KL6904
4.1.4.2 Wiring
Up to eight connections enable the connection of solid or finely stranded cables to the Bus Terminals.
The terminals are implemented in spring force technology. Connect the cables as follows:
1. Open a spring-loaded terminal by slightly pushing with a screwdriver or a rod into the
square opening above the terminal.
2. The wire can now be inserted into the round terminal opening without any force.
3. The terminal closes automatically when the pressure is released, holding the wire safely
and permanently.
Wire cross section 0.08 ... 2.5 mm2
Strip length 8 mm