BECKHOFF EL9xxx System Terminal Guide

Beckhoff EL9xxx System Terminal Selection and Engineering Guide

In the EtherCAT terminal system, the vast majority of users focus on "functional" terminals such as digital input/output, analog acquisition, or motion control. However, a reliable, maintainable, and safety compliant automation system often relies on those silently working "system terminals" - they are responsible for power feeding, potential isolation, shielding grounding, E-bus current enhancement, surge protection, and energy storage buffering. Beckhoff categorizes these types of terminals as the EL9xxx series, which includes end caps, feed terminals (24 V DC/230 V AC), potential distribution terminals, shielding terminals, E-bus power feed terminals, surge filters, and buffer capacitor terminals.

This article is aimed at automation system integration and on-site maintenance engineers, systematically reviewing the technical parameters, internal wiring, installation location requirements, "non-interference" characteristics related to TwinSAFE safety applications, special conditions for explosion-proof (ATEX/IECEx/cFMus), and common design misconceptions of various models in the EL9xxx series. Whether you are renovating an old Woodward controller or planning an EtherCAT network for a new production line, selecting these system terminals correctly will significantly improve the reliability, anti-interference ability, and safety of the system.

End and isolation terminals: EL9011, EL9012, EL9080

1.1 EL9011/EL9012- Bus End Cover Plate

The rightmost end of each EtherCAT terminal station must be equipped with an end cover plate to provide mechanical protection and ESD protection. EL9011 has a width of 8mm (effective alignment width of 5mm), while EL9012 has a width of 8mm but a slightly higher height (55mm). Both do not have any electrical function and only serve as physical end caps. EL9011 is suitable for standard shell depths (34   mm), while EL9012 is suitable for deeper terminals (such as power terminals). Without an end cover, it can cause E-bus signal reflection, unstable communication, and may damage the spring contact of the last terminal.

1.2 EL9080- Potential Separation Terminal

EL9080 is used to interrupt power contacts while the E-bus continues to pass through. The orange front panel clearly indicates the interruption of power contacts. When it is necessary to mix different voltage groups within the same terminal station (such as a 24V DC power contact on the left and a 230V AC power contact on the right), EL9080 must be inserted for electrical isolation. Otherwise, short circuits may occur between potential groups of different voltages, damaging equipment or causing fires.

Feed terminal: EL9100、EL9110、EL9150、EL9160、EL9190、EL9200、EL9210、EL9250、EL9260、EL9290

The feeding terminal is used to establish a new potential group at any position of the terminal station or to supplement the power supply for high current applications. They introduce external power into the power contacts, while the E-bus is transparently transmitted.

Model Rated Voltage Diagnostic Function Fuse Special Instructions

EL9100 24V DC without standard feed

EL9110 24V DC has (1 diagnostic bit) and no diagnostic bit indicating normal power contact voltage

EL9190 230V AC/DC None Suitable for AC or DC high voltage (up to 230V)

EL9150 230   V AC (120   V AC) without AC power supply

EL9160 230   V AC (120   V AC) with (1) no diagnostic position "PowerOK"

EL9200 24V DC without 6.3 A built-in fuse overcurrent protection

EL9210 24V DC with (2 bits: PowerOK+FuseError) 6.3 A fuse status readable

EL9250 230   V AC without 6.3   A AC with fuse

EL9260 230   V AC with (2 digits) 6.3   A diagnosis PowerOK+FuseError

EL9290 230   V AC (variable) No universal high voltage feed, no fuse

Key wiring: All feeding terminals are provided with two sets of parallel input terminals (for example, terminals 1 and 4 of EL9100 are both+24   V, terminals 2 and 5 are both 0   V, and terminals 3 and 6 are both PE), allowing for loop in and loop out. When it is necessary to transmit the same power supply to multiple terminals on the right side, this feature can be used to reduce external jumpers.

Diagnostic function usage: The process images of EL9110, EL9160, EL9210, and EL9260 contain diagnostic bits. In the TwinCAT tree, these terminals will display "PowerOK" and/or "FuseError" variables. If the voltage is lower than about 17   V (for a 24   V system), PowerOK becomes False; If the fuse blows, FuseError becomes TRUE. It is recommended to monitor these bits in the PLC program and trigger alarms or safety shutdowns in case of faults.

Explosion proof environment precautions: When using power supply terminals in ATEX Zone 2 or Class I Division 2 areas, fuses must be replaced only in a power-off or non explosive environment (for EL9200/9210/9250/9260).

Potential distribution terminals: EL9180-EL9189

When it is necessary to extend the power contact voltage to multiple sensors or actuators, using potential distribution terminals can avoid external wire terminal blocks.

Model, Terminal Point, Potential Number, Description