BECKHOFF EL1904 - Manual (Page 37)

Operation
EL1904 35
4.4 Diagnostics
4.4.1 Diagnostic LEDs
The LEDs Diag 1 to Diag 4 display diagnostic information for the EL1904.
4.4.1.1 Diag 1 (green)
The Diag 1 LED indicates the state of the TwinSAFE interface.
Flashing Code Meaning
LED illuminated continuously normal operation:
TwinSAFE communication OK
rapid flickering, alternating with 1 flash pulse Error in S parameter (TwinSAFE parameter)
rapid flickering, alternating with 2 flash pulses Error in I parameter (Individual parameter)
rapid flickering, alternating with 3 flash pulses Waiting for S and I parameter
rapid flickering, alternating with 4 flash pulses S- and I-parameter correct:
waiting for first host message
rapid flickering, alternating with 5 flash pulses Watchdog error
rapid flickering, alternating with 6 flash pulses CRC error
rapid flickering, alternating with 7 flash pulses Sequence number error
rapid flickering, alternating with 8 flash pulses Communication error in the TwinSAFE protocol
4.4.1.2 Diag 2 (red)
The Diag 2 LED illuminates red if the terminal detects an external supply or cross-circuit. The LED
extinguishes once the error is rectified.