BECKHOFF EK1914 - Manual (Page 37)

Operation
EK1914 35
4.4 Diagnostics
4.4.1 Diagnostic LEDs
The LEDs Diag 1 (LED 7) and Diag 2 (LED 15) display diagnostic information for the EL1914.
4.4.1.1 Diag 1 (green)
The Diag 1 LED indicates the state of the TwinSAFE interface. The LED is set as soon as the FSoE State
Reset is quit and TwinSAFE communication is thus started.
4.4.1.2 Diag 2 (red) steady
The Diag 2 LED illuminates red if the Bus Coupler detects an external supply or cross-circuit. The LED
extinguishes once the error is rectified.
A more precise error cause is set in the diagnostic CoE object 0x800E (see section 4.4.2).