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Alarm, error and system messages
4.1 Status and error display of the CPU
Note
MAINT LED of the two CPUs
The MAINT LEDs of both CPUs only go out when the following conditions are fulfilled:
• The CPUs are in the RUN-Redundant system state.
• No maintenance is demanded.
Note
LED displays in redundant operating state
In the RUN-Redundant system state, the LED displays on both CPUs are identical (exception:
you are performing an LED flash test on one CPU).
Meaning of LINK RX/TX LED
Each port of the X1, X2, X3, X4 and X5 interfaces has a LINK RX/TX LED. The table below
shows the various LED patterns of the CPU 1518HF-4 PN ports.
Table 4- 2
Meaning of LINK RX/TX LED
LINK TX/RX LED
Off
Flashes green
Illuminated green
LED flashes
yellow/green
Note
"LED" instruction
You can read the status (e.g. "On" or "Off") of LEDs of a CPU or a module using the "LED"
instruction. Note, however, that it is not possible to read the LED status of the LINK RX/TX
LEDs on all S7-1500 R/H CPUs.
You can find additional information on the "LED" instruction in the STEP 7 online help.
32
There is no connection between the interface of the device and a communication partner.
No data is currently being sent/received via the interface.
There is no LINK connection.
The redundancy connections were interrupted.
The CPU performs an LED flash test.
There is a connection between the interface of the device and a communication partner.
The redundancy connections are OK.
Data is currently being received or sent by a communication partner via the interface of the
device.
Meaning
CPU 1518HF-4 PN (6ES7518-4JP00-0AB0)
Equipment Manual, 05/2021, A5E49868646-AA
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