LED signaling Power LED The power LED indicates the current status. Normal operation In normal operation, the green power LED L1 flashes briefly once per second. Case of an error If an error has occurred, the LED turns red and signals an error number.In the following figure, the error number 3 is signaled. The following table shows the meaning of the error numbers. Flash rate Error 1 General 2 Voltage 3 Temperature 4 Overcurrent 5 Controller 6 Watchdog-Reset Note: For each error that occurs, a more precise error code is stored in object 1003h. Tip: You can switch off the power LEDs with 3250h:09h. EtherCAT LEDs The PD4-E is equipped with three LEDs (LINK, RUN, ERR) which indicate the status of the controller on the EtherCAT bus. LINK The green LINK LEDs are on if the EtherCAT cable is connected and flash during data transfer . RUN The green RUN LED indicates one of the following controller states (EtherCAT slave): LED behavior Status Prerequisite Permanently off INIT The slave is in the initialisation state. Flashing PRE-OPERATIONAL The slave is in the PRE-OPERATIONAL state. Single flash SAFE-OPERATIONAL The slave is in the SAFE-OPERATIONAL state. Flickering INITIALISATION or BOOTSTRAP The slave is in the initialisation phase and has not yet achieved the INIT status or the slave is in boot loader mode and firmware is being loaded. continuously green OPERATIONAL The slave is in the OPERATIONAL state. ERR The red ERR LED indicates one of the following controller states (EtherCAT slave): LED behavior Status Prerequisite Permanently off No error Not an error Flashing Invalid Configuration General configuration error Single flash Local Error The slave automatically changed its EtherCAT status due to a local error. Double flash Process Data Watchdog Timeout/ EtherCAT Watchdog Timeout Watchdog timeout Triple flash Application Error Error in the power state machine of the slave Flickering Booting Error Error when loading the firmware continuously red Application controller failure The slave no longer responds.