To the DeltaV system, a redundant pair is one logical redundant card. In parameter paths and Device Signal Tags (DSTs), the DeltaV system references the pair as a single item composed of two cards. The DeltaV system uses the standard I/O prefix, Cxx, to access information about the pair where xx is the lower (odd) slot number occupied by the pair. For example, the DeltaV system references redundant cards in slots 1 and 2 as C01 in paths and in default, DST names. Use the Cxx prefix (such as C01) in a path to access information about the pair of cards. For example, to return overall status information about a redundant pair in slots 1 and 2 on controller CTLR-1A, use the path: CTLR-1A/IO1/CO1/STATUS.
DSTs are associated only with the pair, not with an individual card within the pair. For example, an AI block would use the following path to reference a value from a redundant pair in slots 1 and 2: C01/CH01/FIELD_VAL_PCT.
Similarly, configuration parameters for cards, ports, and channels reference the pair. There is no configuration for a specific card in the pair. To access the value for the FILTER parameter for channel 1 of a redundant pair in slots 1 and 2, use the following path:C01/CH01/FILTER.
However, some diagnostic parameters permit access to an individual card within the pair. The path to these parameters consists of the path identifier for the pair, such as C01, plus the physical card to be accessed. For example, to read the overall integrity of the standby card, use the path: CTLR/IO1/C01/STBY_OINTEG.
To determine which slot contains the active and standby cards, use the paths: CTLR/IO1/C01/ACT_SLOT and CTLR/IO1/C01/STBY_SLOT.