Siemens SIMATIC S7-1500 Manual page 63

Interrupts, diagnostics alarms, error messages and system alarms
4.1 Status and error displays
LED display during reset
At POWER ON, the SIMATIC Drive Controller performs a reset. During the reset, all LEDs
are lit yellow (lamp test).
LED display in FREEZE state
The FREEZE state signifies a "continuous reset". You can only exit this reset by switching
the power supply of the Drive Controller off and back on again.
While in Freeze state, the LEDs retain their last display status and the RUN/STOP LED
flashes red. The 7-segment display is reset, during which all 7 segments including the two
dots are lit.
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SIMATIC Drive Controller
Equipment Manual, 11/2019, A5E46600370-AA