Siemens SIMATIC S7-1500R/H Equipment Manual page 25

Reference
You can find a brief overview of the various operating states and system states in the section
Status and error display of the CPU (Page 30).
You can find a detailed description of the operating states and system states in the system
manual for S7-1500R/H Redundant System
(https://support.industry.siemens.com/cs/ww/en/view/109754833).
CPU 1517H-3 PN (6ES7517-3HP00-0AB0)
Equipment Manual, 11/2022, A5E42011886-AD
Product overview
3.6 Mode selector
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