BECKHOFF EL2911 Safety Feed Terminal Debugging Guide

Electrical wiring and sensor connection

4.1 Terminal allocation

Input side (1-8): Odd numbers are clock outputs (+), even numbers are safe inputs (-). For example, terminals 1 and 2 form channel 1, terminals 3 and 4 form channel 3, terminals 5 and 6 form channel 2, and terminals 7 and 8 form channel 4. Note: The channel numbering sequence on the PCB is 1, 3, 2, and 4, which are actually arranged in order.

Output side (1 '~8'): 1 'and 6' are safety output contacts (internally short circuited), 3 'and 7' are GND_UP, and 4 'and 8' are 24V UP power supplies. The top and bottom power contacts are also OUT1 and GND, respectively.

Sensor cable: up to 100m (shielded or unshielded, 0.75/1mm ²). The typical current output of the clock is 10mA, with a maximum of 12mA. The test pulse can be configured with filtering time and pulse frequency in the CoE.

4.2 Input characteristic curve

Input signal voltage: Low level -3~5V, High level 11~30V (Type 3). The internal test pulse length is adjustable (multiple 400 μ s), and the input filtering defaults to 2ms (the internal test pulse cannot be turned off). To distinguish between effective signals and test pulses, set "DiagTestPulseFilterTime" (default 0.2ms) to filter out test pulses.

TwinCAT configuration and parameterization (including integrated logic)

5.1 Address Setting

The 10 bit DIP switch on the left side of EL2911 is used to set the TwinSAFE address (1~1023). Each address is unique in the network, address 0 is invalid. The switch is encoded in binary (ON=1) and needs to be changed after power off.

5.2 Adding modules and alias devices

Insert EL2911 into TwinCAT like a regular EtherCAT terminal. If used as a slave, it needs to be automatically or manually imported through "Alias Devices" in the security project and mapped to logical modules. If local logic (non-2200) is enabled, select EL2911 as the target system in Safety Editor, and after downloading the project, it will become the main logic station; To restore as a slave, you need to delete project data (right-click → Delete project data) and power off and restart.

5.3 Key CoE parameters (set through alias devices)

Output parameter (0x8000):

Standard outputs active (default False): If True, the safe output and standard output (internal logic and) are jointly controlled.

Diag TestPulse active (default TRUE): Enable output diagnostic pulses (24V output itself has no pulses, only diagnostic).

Output cross circuit detection delay (default 1000 μ s): After turning off the output, the voltage reading is delayed. If it is>5V, a module error is reported.

Input parameters (0x8010/0x8011):

Modulus DiagTestPulse (0~255): Test pulse frequency modulus, 0=every time, 1=every two times, etc.

MultiplierDiagTestPulse (default 1): Pulse length=multiple x 400 μ s.

Diag TestPulse active (default TRUE): Enable input test pulse.

InputFilterTime (default 0x0014=2.0ms): Input signal filtering time.

DiagTestPulseFilterTime (default 0x0002=0.2ms): A filter used to filter test pulses.

Warning: It is strictly prohibited to directly modify the CoE object, otherwise the terminal will enter the Fail Stop state.

5.4 Process Imaging

Input 6 bytes: containing 4 channel statuses, module errors, and error confirmation bits; Output 6 bytes: Contains secure output control bits and error confirmation bits.

Response time and watchdog

Typical response time (normal operating conditions without faults):

Sensor response 5ms+input delay 4ms+communication (3 times EtherCAT cycle, assuming 1ms)+logic processing 10ms+output delay 3ms+actuator 20ms ≈ 48ms.

Worst case response time (simultaneous occurrence of communication failure):

Watch dog time (default 15ms) x 2+actuator response 20ms=50ms. The system can reliably cut off within 50ms.

The watchdog time can be configured in the TwinSAFE connection parameters and needs to be adjusted according to the actual EtherCAT cycle.

Diagnosis and troubleshooting

7.1 LED Status Indication

Input/output LED (green): It lights up when the corresponding channel is set.

Diag 1 (green): Always on indicates normal environment/voltage; When flashing, cooperate with Diag 2 to output logic or environmental error codes.

Diag 2 (red): The flashing code indicates the specific type of error (see table below).

Diag 3/4 (red): μ C1/μ C2 global fault or global shutdown (if it is constantly on, the component needs to be replaced).

Diag Out (red): Output module error.

Logic error code (Diag1 lit): 1=Function block error, 2=Communication error, 3=Combination, 4=Universal, 5-7=Combination.

Environmental error code (Diag1 off): 1/2=μ C1 overpressure/undervoltage, 3/4=μ C2 overpressure/undervoltage, 5=overtemperature, 6=low temperature, 7=excessive temperature difference, 10=general error.

7.2 Diag History

EL2911 supports ETG.1020 diagnostic history, stored in CoE object 0x10F3, with a maximum of 64 messages. Each entry contains a timestamp, type (information/warning/error), text ID, and dynamic parameters. In TwinCAT, you can view it through the "Diag History" tab, or set 0x10F3:05=1 through the startup list to simultaneously send emergency messages to the main station.