Tag Addressing

A separate variable tag needs to be added to your Plant SCADA project for each group address within the KNX system you would like Plant SCADA to communicate with.

Variable tag addresses are configured according to the following formats:

x/y/z:a[!w]

or

x/y/z:a.b[!w]

Where:

• x is the main group number [0-31].

• y is the sub group number [0-7].

• z is the group address [0-255].

• a is the main encoding type.

• b is the minor encoding type.

• !w is an optional flag to define a tag as write only.

The main, sub and group address fields are specified in decimal. The encoding types are specified in decimal, with leading zeros to pad to three characters for the minor encoding type.

The minor encoding type is optional. If the minor encoding is not specified, then an encoding that matches as close as possible to an unscaled memory copy shall be chosen. See KNX Data Type Mappings for a full list of Plant SCADA data type mappings.

Tag Ranges

Some data types will not map directly to Plant SCADA data types. In some cases, a tag may not span the entire range of values of a given type. Instead, it uses a reduced set of values that represent the actual values within that range.

For example, 3-bit controlled types are typically used in applications such as opening or closing shades. The controller can be instructed to open or close based on a percentage amount. This is mapped through to an INT tag in Plant SCADA that will take a value in the range -100, -50, -25, -12, -6, -3, -1, 0, 1, 3, 6, 12, 25, 50, 100, representing how much to open or close by.

Plant SCADA will convert a representative value used by a device to reflect the actual value, allowing for more meaningful interpretation.

Examples