Summary
Infrastructure for EtherCAT/Ethernet
6
Version: 2.1
• Extended standard series (ISO24702, EN51918 et al.) have been drawn up especially for industrial
concerns and deal with environmental conditions or with protocol-specific regulations, for example.
However, they do not affect the basic electro-technical principles according to EN50173.
• The performance (i.e. the reliable transmission of 10/100/1000 Mbit/s) of Ethernet cabling generally
depends on the following factors:
- the cable quality (attenuation, cross-section, cable structure, screening) of the individual subsections
- the plug quality (fit, screening, cable suitability)
- the number of intermediate connections
- the ambient temperature (20 to 60 °C, specified with derating according to EN50173)
- Environmental influences (e.g. MICE classification according to EN50173-1, chapter 5: Mechanical/
Ingress/Climatic/Electromagnetic rating)
• In the EtherCAT application area, only the connection performance of 100 Mbit/s FastEthernet
according to EN50173 Class D [up to 100 MHz] is required and is dealt with below. It is permissible for
the user to demand connection classes with a higher performance (classes E [up to 250 MHz], E
A
, F
[up to 600MHz MHz], F
A
), but this is not technically justified.
• In order to achieve this performance class, only Ethernet components conforming to EN50173 Cat. 5
(minimum) are permissible; see EN50173-3, chapter 1.2, among others.
Components according to EN50173 Cat. 5 are sufficient, but when using wall feed-throughs/double
couplers, these must conform to EN50173 Cat. 6 in order to achieve performance class D.
• This document deals at present only with copper-based Ethernet 100Base-TX cabling, not fiber optic
cabling according to 100Base-FX.
• 4-core/2-pair cables are favored in Industrial Fast Ethernet, as opposed to the fully assigned 8-core/4-
pair cables normally used in building automation. This is to be considered during the acceptance test
(see there).
• The recommended assignment of a 4-core/2-pair industrial Ethernet cable is the 1,2,3,6+ screen
configuration based on TIA-568A.
• The following is recommended for the cable cross-sections:
- Wire structure: stranded or rigid core
- Cross-section: AWG26/7 to AWG22/1 accordingly 7 cores 0.14 mm² (stranded) up to 0.34 mm² rigid.
• According to EN50173-1, the maximum permissible configuration for an Ethernet link is 90 meters of
permanently installed cable plus 2 device connection cables of 5 metres each, with a maximum of four
intermediate connectors. Other configurations, such as a direct 100 m long connection, are to be
designed in accordance with EN50173-3, appendix B and tested in the field for conformity to the
performance class.
• Caution when using expressly
patch
cables/cords: commercially available
patch
cables up to approx.
10 m are subject to considerably more generous limit values as per EN50173-1, chapter 9 than cables
that are intended for permanent installation as per EN50288. Series connection or an over-length
configuration is to be avoided and, if necessary, checked at least by verification – a simple continuity
test is
not
sufficient! Application-specific
patch
cables manufactured from appropriate goods sold by the
meter are also to be checked for their suitability.
• The number of plug connections between the end points is to be reduced to the necessary minimum.
• It is recommended to use exclusively screened Ethernet cables as per EN50288-2 (STP, SF/UTP).
Together with the special twisted pair execution, the cable screen is instrumental in preventing the
interspersion of interference into the communication cable and thus ensures the reliable operation of
the communication link. The terminal devices must support the screen connection.
In particular when using field-configurable connectors, it must be ensured that there is a technically
perfect, state-of-the-art screen connection between the connector and the cable (see also EN50174-2
and general VDE screening regulations). The qualitative testing of the screening effect is only possible
in the laboratory at present (2011). Therefore, perfect workmanship must be ensured in the execution.
- There must be 360° screen contact at all transitions. Pigtails (twisting the screen braid together
before the contact) are not permitted.
- The screen contact must also be guaranteed on a long-term basis (mechanical or chemical
influences).
- Interruptions and small holes in the screen must be avoided.
- The cable screen must not be used for strain relief.
- The screen material must meet the electrical and mechanical requirements. Special cables are to be
used for drag chains or garlands.
The instructions of cable and connector manufacturers are to be observed.
