Siemens SIMATIC S7-400H System Manual page 48

Installation of a CPU 41x–H
5.3 Status and error displays
REDF LED
The REDF LED indicates specific system states and redundancy errors.
REDF LED
B
0.5 Hz
B
2 Hz
D
H
D = LED is unlit; L = LED lights up; F = LED flashes at the specified frequency
Diagnostic buffer
In STEP 7, you can select "PLC -> Module Information" to read the cause of an error from
the diagnostic buffer.
48
System state
Link-up
Update
Redundant (CPUs are redundant)
Redundant (CPUs are redundant)
Constraints
-
-
No redundancy error
There is an I/O redundancy error:
Failure of a DP master, or partial or total
•
failure of a DP master system
Loss of redundancy on the DP slave
•
System Manual, 09/2007, A5E00267695-03
S7-400H