Specifications

Interrupts/diagnostics alarms
5.1 Status and error displays
DI 16x24VDC HF Digital Input Module (6ES7521-1BH00-0AB0)
Manual, 07/2014, A5E03485952-AD
21
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 24).
RUN and ERROR LED
Table 5- 1 Status and error displays RUN and ERROR
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
The module starts and flashes until the valid
parameter assignment is set.
---
On
Off
Module is configured
On
Flashes
Indicates module errors (at least one error at
one channel, e.g., wire break).
Evaluate the diagnostics data and eliminate
the error (e.g., wire break).
Flashes
Flashes
Hardware defective Replace the module.
PWR LED
Table 5- 2 PWR status display
LED PWR
Meaning
Remedy
Off
Supply voltage L+ too low or missing Check supply voltage L+.
On
Supply voltage L+ is present and OK ---