
Design Guide
EJ8xxx
Signal-Distribution-Board for standard EtherCAT plug-in
modules
Version:
Date:
6.1
2019-11-22

Table of contents
Table of contents
1 Foreword ....................................................................................................................................................5
1.1 Notes on the documentation..............................................................................................................5
1.2 Safety instructions .............................................................................................................................6
1.3 Documentation issue status ..............................................................................................................7
1.4 Purpose and area of application........................................................................................................7
2 Technical data - Signal distribution board..............................................................................................8
3 Backplane mounting guidelines...............................................................................................................9
3.1 Minimum distances for ensuring installability ....................................................................................9
3.2 Installation positions ........................................................................................................................10
4 Module placement ...................................................................................................................................11
5 PCB - distances and footprint ................................................................................................................13
6 Structure of the PCB layers....................................................................................................................14
7 Design of power supply ..........................................................................................................................19
8 Physical Communication Layer .............................................................................................................21
9 Routing guildelines .................................................................................................................................22
9.1 EMC guidelines ...............................................................................................................................23
9.2 Impedance and Routing ..................................................................................................................23
10 Appendix ..................................................................................................................................................24
10.1 Support and Service ........................................................................................................................24
EJ8xxx 3Version: 6.1

Foreword
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®, EtherCAT®, EtherCATG®, EtherCATG10®, EtherCATP®, SafetyoverEtherCAT®,
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.
EJ8xxx 5Version: 6.1

Foreword
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.
EJ8xxx6 Version: 6.1

Foreword
1.3 Documentation issue status
Version Comment
6.1 • Update chapter Structure of the PCB layers
6.0 • Migration
• Update structure
1.4 Purpose and area of application
This document is meant for developers who would like to create a backplane or an EJ distribution board
upon which standard EtherCAT plug-in modules should be used.
This document gives information about the general design of an EJ distribution board for standard EtherCAT
plug-in modules.
When secure EJ modules should be used along with standard EtherCAT plug-in modules please note the
additional requirements and notes of the supplementary Design Guide EJ-Backplane for TwinSAFE-modules.
EJ8xxx 7Version: 6.1

Technical data - Signal distribution board
2 Technical data - Signal distribution board
Technical data Signal distribution board
PCB layer stack Multilayer PCB, min. 4 layers
PCB thickness 1.6mm ± 10%
Board connector
Placing of modules [}11]
E-bus power supply [}19]
Refresh of E-bus power supply [}20]
Air gap and leakage distances [}12] between E-
bus- and field signals
Differential impedance [}23] of the LVDS traces
SGND connection via mounting bolts
Mounting hole distances max. 100mm
Reaching area [}9]
Module depth above PCB min. 55mm
Distance between PCB and mounting surface min. 4mm
Mounting position Standard
Samtec: SSQ-120-01-L-D
Starting from the left:
Coupler, power supply module, EJ-modules
EJ1100 (2.2A)
EJ1101-0022 + (EJ9400 (2.5A) or EJ9404 (12A))
CX + EK1110-0043
EJ9400 (2.5A)
EJ9404 (12A)
typ. 1.2mm
100Ω
92mm
NOTE
Damage to devices possible
Note the specifications and notes for the components used!
EJ8xxx8 Version: 6.1