Interrupts, diagnostics, error messages and system events
4.1 Status and error display of the CPU
CPU 1517H-3 PN (6ES7517-3HP00-0AB0)
34
Equipment Manual, 11/2019, A5E42011886-AB
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.