Siemens SIMATIC S7-1500 Manual page 38

Meaning of the STOP ACTIVE LED
The following table shows the meaning of the STOP ACTIVE LED for the CPU 1511-1 PN.
Table 4- 3 Meaning of the LEDs
STOP ACTIVE LED
LED lit yellow
LED off
CPU 1511-1 PN (6ES7511-1AK02-0AB0)
Equipment Manual, 05/2021, A5E40869673-AB
The CPU is switched to "STOP" mode using the STOP button.
• As long as the STOP ACTIVE LED is lit up, switching the CPU to RUN mode is only possible
using the RUN button.
• The CPU can then no longer be set to RUN mode via the display operation or via online func-
tions. The state of the buttons is retained at power-off. If the CPU does not start up auto-
matically after a power-on, you have to keep the STOP button pressed during start-up until
the STOP ACTIVE LED is activated.
• If an automatic start-up is to be reliably prevented after a power-up, the STOP button has to
be kept pressed during the start-up of the CPU until the STOP ACTIVE LED is activated.
• The CPU is set to "STOP" mode using the display or programming device and not with the
STOP button on the device.
• The CPU is in RUN mode.
Interrupts, error messages, diagnostics and system alarms
4.1 Status and error display of the CPU
Meaning
37