Siemens ESM - Manual (Page 81)

Firmware Update
Industrial Ethernet OSM/ESM
C79000-Z8976-C068-10
77
Start the download by pressing the "Set/Select" button again.
Downloading can take up to 10 minutes. After you have downloaded the firmware
successfully, the device is automatically started with the new firmware. Please note
the version of the new firmware on a label on the side labeling panel of the
OSM/ESM.
Note
During the download, do not interrupt the connection between the PC and
OSM/ESM or turn off the power supply to the OSM/ESM. If the firmware could not
be downloaded completely to the OSM due to a power failure, the message
"Firmware in flash is faulty" appears after the device starts up. This means that the
firmware must be downloaded again.