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If the register is defined in the 30,xxx address range, the status values will be stored in the local device's RTDB (i.e., the RTDB defined as a child to this FieldUnit). If the register is in the 40,xxx range, the values will be stored in the Status/Control Field Unit RTDB. The Comm Status Holdreg is optional, and can be set to 0 to disable the storage of status registers.
See the section Communication Status Registers in the RediGate Configuration Manual for a description of the five Comm Status Register contents.