BECKHOFF EP1908 - Manual (Page 26)

Operation
24 EP1908-0002
4.4 Diagnostics
4.4.1 Run LED diagnostics
The Run LED shows diagnostic information for the EP1908-0002.
4.4.1.1 Run LED (green)
The Run LED lights green when the EP1908-0002 has booted without error.
4.4.1.2 Run LED (red)
The Run LED lights red when the TwinSAFE EtherCAT Box has detected an error, such as cross-circuit,
external feed or exceeding of the maximum frequency.