Siemens Simatic series Manual page 36

Meaning of the LED displays
The following tables explain the meaning of the status and error displays. Remedial
measures for diagnostic reports can be found in chapter Diagnostics alarms (Page 38).
RUN and ERROR LED
Table 5- 1 Status and error displays RUN and ERROR
LED
RUN ERROR
Off Off
Flashes Off
On Off
Flashes
On
Flashes Flashes
PWR LED
Table 5- 2 PWR status display
LED PWR
Off
On
CHx LED
Table 5- 3 CHx status display
LED CHx
Off
On
On
DI 16x24VDC HF Digital Input Module (6ES7521-1BH00-0AB0)
Manual, 08/2018, A5E03485952-AG
Meaning
Voltage missing or too low at backplane
bus
The module starts and flashes until the
valid parameter assignment is set.
Module is configured
Indicates module errors (at least one
error at one channel, e.g., wire break).
Hardware defective
Meaning
Supply voltage L+ too low or missing
Supply voltage L+ is present and OK
Meaning
0 = Status of the input signal
1 = Status of the input signal
Diagnostics: Wire break
Supply voltage L+ too low or missing
Interrupts/diagnostics alarms
5.1 Status and error displays
Solution
Switch on the CPU and/or the system power supply
•
modules.
Verify that the U connectors are inserted.
•
Check whether too many modules are inserted.
•
---
Evaluate the diagnostics data and eliminate the error
(e.g., wire break).
Replace the module.
Solution
Check supply voltage L+.
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Solution
---
---
Check the wiring. When using simple switches, deacti-
vate diagnostics or connect a resistor (25 kΩ ... 45 kΩ)
to the encoder contacts.
Check supply voltage L+.
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