Siemens Simatic S7-1500 Manual page 34

Interrupts, error messages, diagnostics and system alarms
4.1 Status and error display of the CPU
Meaning of LINK RX/TX LED
Each port has a LINK RX/TX LED. The table below shows the various "LED scenarios" of
ports for the CPU 1516-3 PN/DP.
Table 4- 2 Meaning of the LEDs
LINK TX/RX LED
LED off
LED flashes green
LED lit green
LED flickers yellow
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There is no Ethernet connection between the PROFINET interface of the PROFINET device
and the communication partner.
No data is currently being sent/received via the PROFINET interface.
There is no LINK connection.
The "LED flashing test" is being performed.
There is an Ethernet connection between the PROFINET interface of your PROFINET de-
vice and a communication partner.
Data is currently being received from or sent to a communications partner on Ethernet via
the PROFINET interface of the PROFINET device.
Meaning
CPU 1516-3 PN/DP (6ES7516-3AN01-0AB0)
Manual, 09/2016, A5E03461313-AD