Serial devices and the DeltaV system

Maximum number of values for datasets

The following table defines the number of values supported in a dataset depending on the PLC data type and the DeltaV data type defined for the dataset.

When mapping serial device register data to 32-bit signed or unsigned integers or floating point values, the Serial Card maps two consecutive serial device registers to one of these 32-bit data values. Therefore, when calculating the actual number of DeltaV parameters associated with a dataset of these types (32-bit signed or unsigned integer or floating point), the number of DeltaV parameters is half the number of values configured for the dataset.

If the data type is string, the Serial Card reads one string from the serial device. The size of the string is defined by the Number of values field. The size is the number of values × 2. The default value for the number of values field is 1.

Table: Maximum number of values for datasets

Serial device data type

DeltaV data type

Maximum number of values

Coils, Input Status

All except 32-bit signed and unsigned integer and floating point

100

Coils, Input Status

32-bit signed and unsigned integer and floating point

50

Input Registers, Holding Registers

All data types

100

Diagnostics

All data types

17