Beckhoff KS2784 User manual

Documentation | EN
KL2784/KS2784, KL2794/KS2794
Four channel bus terminals with digital switching outputs, solid
state
2021-06-17 | Version: 2.1.0

Table of contents
KL2784/KS2784, KL2794/KS2794 3Version: 2.1.0
Table of contents
1 Foreword ....................................................................................................................................................5
1.1 Notes on the documentation..............................................................................................................5
1.2 Safety instructions .............................................................................................................................6
1.3 Documentation issue status ..............................................................................................................7
2 Product overview.......................................................................................................................................8
2.1 KL2784 - Introduction ........................................................................................................................8
2.2 KL2794 - Introduction ........................................................................................................................9
2.3 Technical data .................................................................................................................................10
2.4 LED display .....................................................................................................................................11
3 Mounting and wiring................................................................................................................................12
3.1 Instructions for ESD protection........................................................................................................12
3.2 Installation on mounting rails ...........................................................................................................13
3.3 Connection ......................................................................................................................................16
3.3.1 Connection system .......................................................................................................... 16
3.3.2 Wiring............................................................................................................................... 18
3.3.3 KL2784 - Connection ....................................................................................................... 19
3.3.4 KL2794 - Connection ....................................................................................................... 20
3.4 ATEX - Special conditions (standard temperature range) ...............................................................21
3.5 Continuative documentation for ATEX and IECEx ..........................................................................22
4 Appendix ..................................................................................................................................................23
4.1 Support and Service ........................................................................................................................23

Table of contents
KL2784/KS2784, KL2794/KS27944 Version: 2.1.0

Foreword
KL2784/KS2784, KL2794/KS2794 5Version: 2.1.0
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 documentation and the following notes and explanations are followed when installing
and commissioning these components.
It is the duty of the technical personnel to use the documentation published at the respective time of each
installation and commissioning.
The responsible staff must ensure that the application or use of the products described satisfy all the
requirements for safety, including all the relevant laws, regulations, guidelines and standards.
Disclaimer
The documentation has been prepared with care. The products described are, however, constantly under
development.
We reserve the right to revise and change the documentation at any time and without prior announcement.
No claims for the modification of products that have already been supplied may be made on the basis of the
data, diagrams and descriptions in this documentation.
Trademarks
Beckhoff®, TwinCAT®, 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.
EtherCAT® is registered trademark and patented technology, licensed by Beckhoff Automation GmbH,
Germany.
Copyright
© Beckhoff Automation GmbH & Co. KG, Germany.
The reproduction, distribution and utilization of this document as well as the communication of its contents to
others without express authorization are prohibited.
Offenders will be held liable for the payment of damages. All rights reserved in the event of the grant of a
patent, utility model or design.

Foreword
KL2784/KS2784, KL2794/KS27946 Version: 2.1.0
1.2 Safety instructions
Safety regulations
Please note the following safety instructions and explanations!
Product-specific safety instructions can be found on following pages or in the areas mounting, wiring,
commissioning etc.
Exclusion of liability
All the components are supplied in particular hardware and software configurations appropriate for the
application. Modifications to hardware or software configurations other than those described in the
documentation are not permitted, and nullify the liability of Beckhoff Automation GmbH & Co. KG.
Personnel qualification
This description is only intended for trained specialists in control, automation and drive engineering who are
familiar with the applicable national standards.
Description of instructions
In this documentation the following instructions are used.
These instructions must be read carefully and followed without fail!
DANGER
Serious risk of injury!
Failure to follow this safety instruction directly endangers the life and health of persons.
WARNING
Risk of injury!
Failure to follow this safety instruction endangers the life and health of persons.
CAUTION
Personal injuries!
Failure to follow this safety instruction can lead to injuries to persons.
NOTE
Damage to environment/equipment or data loss
Failure to follow this instruction can lead to environmental damage, equipment damage or data loss.
Tip or pointer
This symbol indicates information that contributes to better understanding.

Foreword
KL2784/KS2784, KL2794/KS2794 7Version: 2.1.0
1.3 Documentation issue status
Version Comment
2.1.0 • Technical data updated
• Chapter Instructions for ESD protection added
• Design of the safety instructions adapted to IEC 82079-1
• New title page
2.0.0 • Migration
1.0.0 • First release
Hardware and firmware versions
Documentation
version
KL2784/KS2784 KL2794/KS2794
Firmware Hardware Firmware Hardware
2.1.0 - 03 - 03
2.0.0 - 02 - 02
1.0.0 - 02 - 02
The K-bus firmware and hardware version (delivery state) are indicated by the serial number printed at the
side of the terminal.
Syntax of the serial number
Structure of the serial number: WWYYFFHH
WW - week of production (calendar week)
YY - year of production
FF - K-bus firmware version
HH - hardware version
Example with serial number 49 08 1B 03:
49 - week of production 49
08 - year of production 2008
1B - firmware version 1B
03 - hardware version 03

Product overview
KL2784/KS2784, KL2794/KS27948 Version: 2.1.0
2 Product overview
2.1 KL2784 - Introduction
KL2784 - Bus terminal, 4-channel solid state output, 30VAC, 48VDC, 2A
The KL2784 digital output terminal is able to switch voltages up to 30VAC, 48VDC using advanced MOSFET
transistors. The semiconductor switches connected to the power contacts represent a substitute for relay
contacts. They are short-circuit proof and free from wear, thereby increasing the availability of the
application. The output is short-circuit-proof to a limited extent. The output transistor can cope with short-
term overcurrents until the fuse is triggered. The Bus Terminal contains four channels that indicate its signal
state by means of light emitting diodes.

Product overview
KL2784/KS2784, KL2794/KS2794 9Version: 2.1.0
2.2 KL2794 - Introduction
Fig.1: KL2794 - Bus terminal, 4-channel solid state output, 30VAC, 48VDC, 2A, potential-free
The KL2794 digital output terminal is able to switch voltages up to 30VAC, 48VDC using advanced MOSFET
transistors. The four potential-free semiconductor switches represent a substitute for relay contacts. They are
short-circuit proof and free from wear, thereby increasing the availability of the application. The output is
short-circuit-proof to a limited extent. The output transistor can cope with short-term overcurrents until the
fuse is triggered. The Bus Terminal has four channels, whose signal state is displayed by LEDs.

Product overview
KL2784/KS2784, KL2794/KS279410 Version: 2.1.0
2.3 Technical data
Technical data KL2784/KS2784 KL2794/KS2794
Number of outputs 4 make contacts
Rated load voltage 0 … 30VAC/DC (pure ohmic load 0 … 48VDC)
Output current 2A per channel
Breakdown voltage 80V
Peak current 5A (100ms), < 50A (10ms)
Short circuit current not short-circuit proof, see peak current
Switching on speed typical 1.8ms, max. 5ms
Switching off speed typical 30ms, max. 50ms
On-resistance typical 0.03Ω
Isolation voltage - < 200V(channel/channel)
Electrical isolation 500V (K-bus/mains voltage)
Special features alternative for relay contacts alternative for relay contacts,
potential-free
Power supply for the electronics via the K-bus and through the power contacts
Current consumption from K-bus typically: 80mA
Bit width in the output process image 4bit
Configuration via the Bus Coupler or the controller
Weight app. 50g
Permissible ambient temperature range
during operation
0°C ... +55°C
Permissible ambient temperature range
during storage
-25°C ... +85°C
Permissible relative air humidity 95%, no condensation
Dimensions (W x H x D) app. 15mm x 100mm x 70mm (aligned width: 12mm)
Mounting [}13] on 35mm mounting rail conforms to EN60715
Vibration/ shock resistance conforms to EN60068-2-6/ EN60068-2-27
EMC immunity/ emission conforms to EN61000-6-2/ EN61000-6-4
Protection class IP20
Pluggable wiring for all KSxxxx terminals
Correct installation position variable
Approvals/ markings CE, cULus [}21], ATEX
Ex marking
Standard Marking
ATEX II 3 G Ex nA IIC T4 Gc

Product overview
KL2784/KS2784, KL2794/KS2794 11Version: 2.1.0
2.4 LED display
Fig.2: LED display
LED Display
Signal LED 1 off Output1 switched off
on Output1 switched on
Signal LED 2 off Output2 switched off
on Output2 switched on
Signal LED 3 off Output3 switched off
on Output3 switched on
Signal LED 4 off Output4 switched off
on Output4 switched on

Mounting and wiring
KL2784/KS2784, KL2794/KS279412 Version: 2.1.0
3 Mounting and wiring
3.1 Instructions for ESD protection
NOTE
Destruction of the devices by electrostatic discharge possible!
The devices contain components at risk from electrostatic discharge caused by improper handling.
• Please ensure you are electrostatically discharged and avoid touching the contacts of the device directly.
• Avoid contact with highly insulating materials (synthetic fibers, plastic film etc.).
• Surroundings (working place, packaging and personnel) should by grounded probably, when handling
with the devices.
• Each assembly must be terminated at the right hand end with a KL9010 bus end terminal, to ensure the
protection class and ESD protection.
Fig.3: Spring contacts of the Beckhoff I/O components

Mounting and wiring
KL2784/KS2784, KL2794/KS2794 13Version: 2.1.0
3.2 Installation on mounting rails
WARNING
Risk of electric shock and damage of device!
Bring the bus terminal system into a safe, powered down state before starting installation, disassembly or
wiring of the bus terminals!
Assembly
Fig.4: Attaching on mounting rail
The bus coupler and bus terminals are attached to commercially available 35mm mounting rails (DIN rails
according to EN60715) 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 compo-
nents with tongue and groove 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 tongue and
groove, the connection will not be operational! When correctly assembled, no significant gap should
be visible between the housings.
Fixing of mounting rails
The locking mechanism of the terminals and couplers extends to the profile of the mounting rail. At
the installation, the locking mechanism of the components must not come into conflict with the fixing
bolts of the mounting rail. To mount the mounting rails with a height of 7.5mm under the terminals
and couplers, you should use flat mounting connections (e.g. countersunk screws or blind rivets).

Mounting and wiring
KL2784/KS2784, KL2794/KS279414 Version: 2.1.0
Disassembly
Fig.5: Disassembling of terminal
Each terminal is secured by a lock on the mounting rail, which must be released for disassembly:
1. Pull the terminal by its orange-colored lugs approximately 1cm away from the mounting rail. In doing
so for this terminal the mounting rail lock is released automatically and you can pull the terminal out of
the bus terminal block easily 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 out of the bus terminal block.
Connections within a bus terminal block
The electric connections between the Bus Coupler and the Bus Terminals are automatically realized by
joining the components:
• The six spring contacts of the K-Bus/E-Bus deal with the transfer of the data and the supply of the Bus
Terminal electronics.
• 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 (up to 24V)
or for higher voltages via power feed terminals.
Power Contacts
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 Termi-
nals) do not or not fully loop through the power contacts. Power Feed Terminals (KL91xx, KL92xx
or EL91xx, EL92xx) interrupt the power contacts and thus represent the start of a new supply rail.
PE power contact
The power contact labeled 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.

Mounting and wiring
KL2784/KS2784, KL2794/KS2794 15Version: 2.1.0
Fig.6: Power contact on left side
NOTE
Possible damage of the device
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 or-
der 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.
WARNING
Risk of electric shock!
The PE power contact must not be used for other potentials!

Mounting and wiring
KL2784/KS2784, KL2794/KS279416 Version: 2.1.0
3.3 Connection
3.3.1 Connection system
WARNING
Risk of electric shock and damage of device!
Bring the bus terminal system into a safe, powered down state before starting installation, disassembly or
wiring of the bus terminals!
Overview
The bus terminal system offers different connection options for optimum adaptation to the respective
application:
• The terminals of ELxxxx and KLxxxx series with standard wiring include electronics and connection
level in a single enclosure.
• The terminals of ESxxxx and KSxxxx series feature a pluggable connection level and enable steady
wiring while replacing.
• The High Density Terminals (HD Terminals) include electronics and connection level in a single
enclosure and have advanced packaging density.
Standard wiring (ELxxxx / KLxxxx)
Fig.7: Standard wiring
The terminals of ELxxxx and KLxxxx series have been tried and tested for years.
They feature integrated screwless spring force technology for fast and simple assembly.
Pluggable wiring (ESxxxx / KSxxxx)
Fig.8: Pluggable wiring
The terminals of ESxxxx and KSxxxx series feature a pluggable connection level.
The assembly and wiring procedure is the same as for the ELxxxx and KLxxxx series.
The pluggable connection level enables the complete wiring to be removed as a plug connector from the top
of the housing for servicing.
The lower section can be removed from the terminal block by pulling the unlocking tab.
Insert the new component and plug in the connector with the wiring. This reduces the installation time and
eliminates the risk of wires being mixed up.
The familiar dimensions of the terminal only had to be changed slightly. The new connector adds about 3
mm. The maximum height of the terminal remains unchanged.

Mounting and wiring
KL2784/KS2784, KL2794/KS2794 17Version: 2.1.0
A tab for strain relief of the cable simplifies assembly in many applications and prevents tangling of individual
connection wires when the connector is removed.
Conductor cross sections between 0.08mm2 and 2.5mm2 can continue to be used with the proven spring
force technology.
The overview and nomenclature of the product names for ESxxxx and KSxxxx series has been retained as
known from ELxxxx and KLxxxx series.
High Density Terminals (HD Terminals)
Fig.9: High Density Terminals
The terminals from these series with 16 terminal points are distinguished by a particularly compact design,
as the packaging density is twice as large as that of the standard 12mm bus terminals. Massive conductors
and conductors with a wire end sleeve can be inserted directly into the spring loaded terminal point without
tools.
Wiring HD Terminals
The High Density Terminals of the ELx8xx and KLx8xx series doesn't support pluggable wiring.
Ultrasonically “bonded” (ultrasonically welded) conductors
Ultrasonically “bonded” conductors
It is also possible to connect the Standard and High Density Terminals with ultrasonically
“bonded” (ultrasonically welded) conductors. In this case, please note the tables concerning the
wire-size width!

Mounting and wiring
KL2784/KS2784, KL2794/KS279418 Version: 2.1.0
3.3.2 Wiring
WARNING
Risk of electric shock and damage of device!
Bring the bus terminal system into a safe, powered down state before starting installation, disassembly or
wiring of the bus terminals!
Terminals for standard wiring ELxxxx/KLxxxx and for pluggable wiring ESxxxx/KSxxxx
Fig.10: Connecting a cable on a terminal point
Up to eight terminal points enable the connection of solid or finely stranded cables to the bus terminal. The
terminal points are implemented in spring force technology. Connect the cables as follows:
1. Open a terminal point by pushing a screwdriver straight against the stop into the square opening
above the terminal point. Do not turn the screwdriver or move it alternately (don't toggle).
2. The wire can now be inserted into the round terminal opening without any force.
3. The terminal point closes automatically when the pressure is released, holding the wire securely and
permanently.
See the following table for the suitable wire size width.
Terminal housing ELxxxx, KLxxxx ESxxxx, KSxxxx
Wire size width (single core wires) 0.08 ... 2.5mm20.08 ... 2.5mm2
Wire size width (fine-wire conductors) 0.08 ... 2.5mm20,08 ... 2.5mm2
Wire size width (conductors with a wire end sleeve) 0.14 ... 1.5mm20.14 ... 1.5mm2
Wire stripping length 8 ... 9mm 9 ... 10mm
High Density Terminals (HD Terminals [}17]) with 16 terminal points
The conductors of the HD Terminals are connected without tools for single-wire conductors using the direct
plug-in technique, i.e. after stripping the wire is simply plugged into the terminal point. The cables are
released, as usual, using the contact release with the aid of a screwdriver. See the following table for the
suitable wire size width.

Mounting and wiring
KL2784/KS2784, KL2794/KS2794 19Version: 2.1.0
Terminal housing High Density Housing
Wire size width (single core wires) 0.08 ... 1.5mm2
Wire size width (fine-wire conductors) 0.25 ... 1.5mm2
Wire size width (conductors with a wire end sleeve) 0.14 ... 0.75mm2
Wire size width (ultrasonically “bonded" conductors) only 1.5mm2
Wire stripping length 8 ... 9mm
3.3.3 KL2784 - Connection
WARNING
Risk of injury through electric shock and damage to the device!
Bring the Bus Terminals system into a safe, de-energized state before starting mounting, disassembly or
wiring of the Bus Terminals!
Fig.11: KL2784 - Connection
Terminal
point
No.: Connection for
Output 1 1 Load 1
0V 2 0V (internally connected to terminal points 3, 6, 7 and power contact for 0V)
0V 3 0V (internally connected to terminal points 2, 6, 7 and power contact for 0V)
Output 3 4 Load 3
Output 2 5 Load 2
0V 6 0V (internally connected to terminal points 2, 3, 7 and power contact for 0V)
0V 7 0V (internally connected to terminal points 2, 3, 6 and power contact for 0V)
Output 4 8 Load 4

Mounting and wiring
KL2784/KS2784, KL2794/KS279420 Version: 2.1.0
3.3.4 KL2794 - Connection
WARNING
Risk of injury through electric shock and damage to the device!
Bring the Bus Terminals system into a safe, de-energized state before starting mounting, disassembly or
wiring of the Bus Terminals!
Fig.12: KL2794 - Connection
Terminal
point
No.: Connection for
Output1 1 Output1: Potential-free contact
Output1 2 Output1: Potential-free contact
Output3 3 Output3: Potential-free contact
Output3 4 Output3: Potential-free contact
Output2 5 Output2: Potential-free contact
Output2 6 Output2: Potential-free contact
Output4 7 Output4: Potential-free contact
Output4 8 Output4: Potential-free contact