Hello,

please see the chapter 

6.11.12 Resetting the "Homed" status (S7-1500, S7-1500T)  V21

Incremental encoder In the following cases, the "Homed" status is reset, and the technology object must be rehomed. • Error in sensor system/encoder failure • Starting an "MC_Home" job with "Mode" = 3, 5, 8, 10 (As soon the homing mark has been approached, the status "Homed" is set to "TRUE".) • Replacement of the CPU • Replacement of the SIMATIC Memory Card • POWER OFF • Memory reset • Modification of the encoder configuration • Restart of the technology object • Restoration of the CPU factory settings • Transfer of a different project into the controller

Absolute encoder In the following cases, the "Homed" status is reset, and the technology object must be rehomed. • Replacement of the CPU • Changing the encoder type to incremental encoder • Restoration of the CPU factory settings • Transfer of a different project into the controller When you use a new absolute value encoder you need to home the absolute encoder once again. Resetting the memory of the CPU or upgrading a project does not require another absolute encoder adjustment.

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