Siemens SIMATIC NET CP 1542-5 Equipment Manual page 18

Product overview, functions
2.5 LEDs
The following table shows the meaning of the various combinations of colors of the
RUN/STOP, ERROR and MAINT LEDs.
Table 2- 3
RUN/STOP LED
LED lit green
LED lit green
LED lit green
LED flashing
LED lit green
LED lit green
LED lit green
LED flashing
Diagnostics with LEDs
Diagnostics using the LEDs is the first means of narrowing down errors/faults. To narrow the
error/fault down even further, evaluate the message on the display of the S7-1500 CPU. If
errors/faults occur, you can also identify them using the Web server or by evaluating the
diagnostics buffer of the CPU. The diagnostics buffer of the CPU contains plain language
information about the error/fault that has occurred. The diagnostics buffer is accessible via
STEP 7, the display and the Web server.
18
Meaning of the LEDs
ERROR LED
LED off LED off
LED lit red
LED lit red
LED off
LED off
green
LED flashing red
LED off
LED off
LED flashing red
green
MAINT LED
No supply voltage on the CP or supply
voltage too low.
LED off
LED test during startup
LED lit yellow
Startup (booting the CP)
LED off
CP is in RUN mode.
LED off No disruptions
No CP configuration exists
Loading firmware
LED off
A diagnostics event has occurred.
LED off
Maintenance, maintenance is demanded.
LED lit yellow
Maintenance is required.
Downloading the user program
LED flashing
yellow
Module fault
LED flashing
yellow
Equipment Manual, 01/2023, C79000-G8976-C326-05
Meaning
SIMATIC CP 1542-5