Beckhoff EP23xx EtherCAT Box Selection Troubleshooting

Beckhoff EP23xx EtherCAT Box Digital I/O Module Selection and Fault Safety Configuration Guide

Distributed I/O modules with IP67 protection level are increasingly favored by equipment integrators in modern industrial automation sites. Beckhoff's EP23xx series EtherCAT Box product line highly integrates digital input/output (DI/DO) into a compact, fully sealed metal/plastic casing that can be directly installed on machines without the need for a control cabinet. However, when faced with numerous models (EP2308, EP2318, EP2328, EP2316, EP2338, EP2339, EP2349, etc.), engineers often need detailed references when selecting, wiring, and handling output behavior when dealing with faults. This article is based on official technical documents, systematically sorting out the key technical parameters, fault safety mechanisms, and explosion-proof installation requirements of this series of modules, helping on-site engineers quickly locate problems and optimize system design.

Product Series Overview and Quick Selection

The core feature of the EP23xx series is the "digital quantity combination module" - a single module has both input and output terminals, and each channel of some models (EP2338/EP2339) can be freely configured as input or output without the need for advance settings. The following table summarizes the differences between the main models:

Model I/O Channel Number Connector Type Output Current/Total Current Input Filter Special Function

EP2308-0001 4 DI+4 DO 8 × M8 0.5A/4A 3.0 ms standard combination

EP2308-0002 4 DI+4 DO 4 × M12 0.5A/4A 3.0 ms large interface

EP2318-0001/2 4 DI+4 DO M8/M12 0.5A/4A 10 μ s high-speed input

EP2328-0001/2 4 DI+4 DO M8/M12 2.0A/4A 3.0 ms high current output

EP2316-0003 8 DI+8 DO ZS2001 spring terminal 0.5A/4A 10 μ s IP20 connection

EP2316-0008 8 DI+8 DO 25 pin D-sub 0.5A/4A 10 μ s standard interface

EP2338-0001/2 8-channel (configurable) M8/M12 0.5A/4A 10 μ s bidirectional combination

EP2338-1001/2 8-channel (configurable) M8/M12 0.5A/4A 3.0 ms slow input

EP2338-2002 8-channel (configurable) 4 × M12 0.5A/4A 10 μ s dual power supply grouping

EP2339-0003 16 channel (configurable) 2 × ZS2001 0.5A/4A 3.0 ms high-density

EP2339-0021 16 channel (configurable) 16 × M8 0.5A/4A 3.0 ms M8 dense

EP2349-0021 16 channel (configurable) 16 × M8 0.5A/4A 10 μ s high-speed version

EP2339-0042 16 channel (configurable) 8 × M12 0.5A/4A 3.0 ms interference suppression type

EP2339-0121 16 channel (configurable) 16 × M8 0.5A/4A 3.0 ms ground switching (low side drive)

Key selection points:

High speed input (such as counting, interruption) is required. Choose EP2318 or EP2349 (10 μ s filtering).

The output needs to drive high current loads (solenoid valves, small motors) and select EP2328 (2A per channel).

EP2339-0003 (spring terminal, IP20 internal use) is selected due to limited space and no need for frequent wire changes.

Require safe shutdown and use of interference suppression standard terminal EP2339-0042 (in conjunction with TwinSAFE application).

The principle of "configuration free" bidirectional channel and power precautions

The biggest feature of the EP2338/EP2339 series is that each physical channel can be used as both input and output simultaneously. Its internal circuit permanently connects the input detection circuit and the output drive circuit in parallel, so when the output is set to "1", the corresponding bit in the input process image will also automatically change to "1". This design eliminates the configuration steps, but brings two important limitations:

Sensor power supply source

Most EtherCAT Box sensors are powered by control voltage UsUs

However, the sensors of EP2338 xxxx and EP2339 xxxx are powered by the peripheral voltage UpUp

This means that if it is cut off for safety reasons UpUp

The sensor will also lose power and the input signal will not be able to be read. This impact must be evaluated during design.

The output may still be charged

For EP2338-2002, the channels of connectors X01 and X02 are UsUs

Power supply, not UpUp

Even if it is cut off externallyUpUp

These outputs may still remain at a high level, which may prevent the expected goal of "all outputs turned off" in the safety circuit from being achieved. Be sure to verify the power grouping diagram of the module.

Detailed Explanation of Fault Safety Behavior (Taking EP2316 as an Example)

The EP2316 series has comprehensive diagnostic functions and can provide configurable responses to network interruptions, output short circuits, and power outages. Mastering these behaviors is crucial for designing a safe shutdown circuit.

3.1 Safe State during Network Interruption

When EtherCAT communication is interrupted or the master station switches to a non operational state (such as Initiat, PRE-OP), the module will stop receiving output process data. The behavior of each channel at this time can be defined through the CoE object:

Object 8000:n - Safe State Active

When set to TRUE (default), the channel will switch to a predefined safe value. When set to False, maintain the last received output value.

Object 8001: 0n - Safe State Value

The specific values for defining the safety state are: False corresponds to output disconnection (0V), and True corresponds to output conduction (24V).

Engineering suggestion: For hazardous actuators (such as holding brakes and emergency stop valves), the safety status should be activated and the safety value should be set to False to ensure that the load automatically loses power when communication is interrupted.

3.2 Behavior during output short circuit

EP2316 can detect short circuits to ground or power in the output channel. Two modes can be configured through object F800:01- Disable shut off:

False (default): If any output is short circuited, all outputs of the module will be immediately latched off. After troubleshooting, it is necessary to reactivate through the Reset outputs bit (rising edge) in the process data.

True: Only the faulty channel itself is turned off, while other channels are working normally. After the short circuit is eliminated, the channel will automatically resume output without the need for manual reset.

In addition, object F800:11- Switch off time (default 1000 ms) defines the time the module waits before attempting to reconnect the output after a short circuit occurs. During the waiting period, we will check if the short circuit has been eliminated.

3.3 Peripheral power supply UpUp

Behavior when missing

The high level of digital output is determined by UpUp

Provide. when UpUp

When lost, even if the output process data is still "1", the actual output pin is also 0V. The module will detect this "output set value does not match the actual level" as a fault and set the Diag Input n and Error Channel y of the corresponding channel in the process image.

Reset method:

Manual: Send a rising edge to the Reset outputs variable.

Auto: Set F800:01=TRUE (note that this will also change the short-circuit behavior mode). when UpUp

After recovery, all outputs are automatically reactivated.

Special conditions for installation in explosion-proof areas (ATEX/IECEx)

If the module needs to be installed in Zone 2 (gas) or Zone 22 (dust) explosive environments, the following mandatory requirements must be followed (from section 4.4 of the document):

Mechanical protection

The module must be installed inside the BG2000-0000 protective casing to prevent mechanical shock and electrostatic discharge risks.

ambient temperature

The allowable working range is 0 ℃~+55 ℃ (standard products are -25 ℃~+60 ℃). Beyond this range, it cannot be used in explosion-proof areas.

Transient overvoltage limit

Measures must be taken to prevent the rated voltage from being superimposed by transient disturbances exceeding 40%, such as those caused by the shutdown of large contactors. Suitable surge suppressors can be used.

Electrostatic protection

The surface of the shell can only be wiped with a damp cloth, and dry wiping is strictly prohibited to avoid static electricity accumulation and ignition in hazardous environments.

Live insertion and removal restrictions

Bus plugs, sensor/actuator connectors, and address dip switches must be plugged in or adjusted only when the power supply is disconnected or when there is no explosive gas confirmed.

Temperature at cable entry point

If the temperature at the cable inlet exceeds 70 ℃ or the branch point exceeds 80 ℃, a cable with higher temperature resistance must be selected.

UV protection

The equipment must not be exposed to ultraviolet radiation (such as direct sunlight) and must be installed in a suitable protective cover.

After meeting the above conditions, the module will be marked with Ex ec IIC T4 Gc or Ex tc IIIC T135 ° C Dc.

Key points and common problems of installation wiring

5.1 Connector tightening torque

Connector type torque

M8 0.4 Nm

M12 0.6 Nm

7/8″ 1.5 Nm

It is recommended to use a Beckhoff ZB8801-0000 torque wrench with the corresponding socket to avoid damaging the plastic casing due to excessive torque.

5.2 Functional Earth

For EPxxxx-002x and EPxxxx-0042 wide body modules, both mounting holes are also functional grounding connection points. The module must be grounded using a low impedance method (such as directly installed on a grounded metal plate) to discharge high-frequency interference currents. If installed on non-metallic surfaces, it should be separately connected to the grounding busbar through a braided ground wire.

5.3 Power supply current limitation and voltage drop

M8 power connector: Maximum total current of 4A, exceeding it can cause the connector to overheat.

7/8 "power connector (EP2339-0042): maximum total current of 16A.

When providing long-distance power, cable voltage drop needs to be considered. For example, using an M8 cable with a length of 2m and a 0.34mm ² core, the voltage drop at a full load of 4A 24V is about 0.5V. It is important to ensure that the voltage reaching the module is not less than 24V -15%=20.4V.

5.4 Inductive load protection

When driving inductive loads such as relays and solenoid valves, a high-voltage back electromotive force will be generated at the moment of shutdown. Although the module integrates a freewheeling diode internally, the switching time is relatively long (which can cause the valve to turn off delayed). It is recommended to directly parallel a freewheeling diode (1N4007 or similar) or RC absorption circuit at both ends of the load to accelerate current decay and protect the output transistor.

Restore factory settings and firmware version recognition

6.1 Restore default parameters

Through TwinCAT's CoE online access, modules can be restored to delivery status with just one click:

Switch TwinCAT to Config mode.

Find object 1011:0 'Restore default parameters'.

Write 0x64616F6C (decimal 1684107116) in its sub index 1011:01.

For some early modules, the alternative value is 0x6C6F6164 (decimal 1819238756).

6.2 Hardware/firmware version identification

The D-number format on the side of the module is D: WWYYFFHH:

WW: Production Week

YY: Year

FF: firmware version (hexadecimal)

HH: Hardware version

For example, D: 29100201 represents production in the 29th week of 2010, firmware version 02, hardware version 01.

The new Beckhoff product also uses Data Matrix Code (BIC), which can be obtained by reading the CoE object 0x10E2:01 online through TwinCAT, where the unique traceability number starts with SBTN.

Typical Fault Case Analysis

Case 1: All outputs cannot be restored after a short circuit

Phenomenon: After a short circuit is caused by a misconnected output, all output lights of the module turn off, and even if the short circuit is repaired and powered on again, the output still does not work.

Reason: The module defaults to "global latch" mode (F800:01=False). After a short circuit occurs, all outputs are locked and cannot be reset by simply powering on.

Solution: Send a rising edge (from 0 to 1) to the Reset outputs variable of the process data through TwinCAT, or set F800:01=TRUE to automatic recovery mode.

Case 2: Output not turned off as expected after communication interruption

Phenomenon: After unplugging the EtherCAT cable, the output of a certain control brake still remains engaged, causing the vertical axis to slide down.

Reason: The security status of the channel is not activated (8000:n=False), and the module continues to maintain the last received output value.

Solution: Set the corresponding channel's 8000:0n to TRUE and 8001:0n to False, so that the output automatically shuts down after a network interruption.

Case 3: EP2338-2002 cutting offUpUp

Some outputs are still charged afterwards

Phenomenon: External safety relay disconnected UpUp

Power supply, but the solenoid valve connected to port X01 remains engaged.

Reason: The output driver of X01/X02 channels is driven by UsUs

Power supply, and UsUs

Still exists (unless separately cut off).

Solution: reallocate the load and connect the safety critical actuators to ports X03/X04 (via) UpUp Power supply), ensure safe shutdown and cut off at the same time. Or cut off simultaneously during design UsUs andUpUp.