Special Relay (Sm); Special Register (Sd) - Mitsubishi Electric MELSEC iQ-R Series User Manual

Special relay (SM)

This is the internal relay for which the specification is defined in the CPU module, where the status of the CPU module is
stored. ( Page 645 List of Special Relay Areas)

Special register (SD)

This is the internal register for which the specification is defined in the CPU module, where the status (diagnostics information,
system information, etc) of the CPU module is stored. ( Page 668 List of Special Register Areas)
27 DEVICES
470
27.4 System Device