Siemens 6ES7521-1BL00-0AA0 - Meaning of LED Displays

Diagnostics alarms
5.1 Status and error displays
Digital input module DI 32x24VDC BA (6ES7521-1BL10-0AA0)
Manual, 12/2016, A5E32363711-AD
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Meaning of the LED displays
The tables below explain the meaning of the status and error displays.
LED RUN/ERROR
Table 5- 1 RUN/ERROR status and error displays
LED
Meaning
Remedy
RUN
ERROR
Off Off
Voltage missing or too low at backplane bus.
• Switch on the CPU and/or the system pow-
er supply modules.
• Verify that the U connectors are inserted.
• Check to see if too many modules are in-
serted.
Flashes
Off
Module is starting up. ---
On Off
Module is ready.
Flashes
Flashes
Hardware defective. Replace the module.
LED CHx
Table 5- 2 CHx status display
LED CHx
Meaning
Remedy
Off
0 = Status of the input signal. ---
On
1 = Status of the input signal. ---