Specifications

Interrupts/diagnostics alarms
5.1 Status and error displays
DI 16x24VDC HF Digital Input Module (6ES7521-1BH00-0AB0)
22 Manual, 07/2014, A5E03485952-AD
CHx LED
Table 5- 3 CHx status display
LED CHx
Meaning
Remedy
Off
0 = Status of the input signal ---
On
1 = Status of the input signal ---
On
Diagnostics: Wire break Check the wiring. When using simple switches,
deactivate diagnostics or connect a resistor
(25 kΩ … 45 kΩ) to the encoder contacts.
Supply voltage L+ too low or missing
Check supply voltage L+.