Siemens SIMATIC S7-1500 Function Manual page 116

Evaluate diagnostics on the display
For example 2, display of the PLC_2 CPU shows:
● In the "Overview" menu command: A message is available in the next lower level page.
● In the "Diagnostics" menu command: A message is available in the next lower level page.
● In the Module menu command: An error has occurred.
To evaluate the display, proceed as follows:
1. Navigate to "Pairing state" via the menu commands "Overview" > "Redundancy".
2. This is displayed as the pairing state: Single paired (X4).
This means that the redundancy connection is available at the H-Sync interface X4, but
not at the X3.
3. Navigate to "Alarms" via the "Diagnostics" menu command.
4. View the details of the alarm (evaluate diagnostics buffer).
S7-1500H Example 3:
A redundancy connection in S7-1500H is interrupted.
Evaluating diagnostics via X3 and X4 LEDs on the CPU
The LED X4 on CPU PLC_1 does not light up. This means:
● The redundancy connection on the synchronization module was interrupted at the H-Sync
interface X4.
or
● There is no synchronization module at the H-Sync interface X4.
Diagnostics
Function Manual, 11/2019, A5E03735838-AF
Diagnostics of the S7-1500R/H redundant system
7.4 Diagnostics in the RUN-Redundant system state
115