The Technical Designation (TD) is a technical identifier that is used to identify the plant and associated elements.

The structure of the TD is based on the hierarchical structure of the plant and its associated elements, e.g.:

  • For primary plants with Desigo PX:
    Site / Plant / Partial plant / Aggregate / Component / Pin
  • For room automation plants with Desigo RX:
    Site / Area / Subarea / Section / Room
  • For room automation plants with Desigo room automation:
    Building / Floor / Room / Room Segment / Functional Unit / Component / Pin

The text is based on designations in abbreviated form that are customary within the industry, e.g.:

GUB:AGeb6‘Ahu3St‘FanSu = Gubelstreet facility / ventilation plans building 6 / Air handling third floor / supply air fan

Technical designations are linguistically neutral (mnemonic). They are based on mnemonic texts set up in the library, with additional project-specific details.

The TD is defined by Siemens. The User Designation (UD) can be defined by the customer.


Each element of the TD is called ShortName. A ShortName is a designation for an individual plant element within the automation station. A ShortName is always linked to a description. This pair is called the Name&Description_Pair.

TD rules



Address structure

Comprises at least one hierarchical object and one function object

Has a variable length (site + 1..8 hierarchy and function objects + pin name)

Is independent of the automation station, that is, does not contain a designation for an automation station

Must be unique for each site


Based on the English terms

Must not be translated

Plant elements on the same hierarchy level are distinguished through different part names, e.g., HG01/HG02.


Site designation

Consists of upper and lower case letters, and numbers (must start with a letter): [a..z, A..Z, 0..9].

Is case insensitive, e.g., Imax and IMAx are treated the same.

Other partial designations

Consist of upper and lower case letters ([A..Z] and [a..z]) and/or numbers 0 to 9.

Is case insensitive, e.g., Imax and IMAx are treated the same.

Max. number of characters

Site: 10

Object: 9

Pin: 8

TD: 80


Colon (:) after site name

Apostrophes (‘) for all other separations

Period (.) in front of pin name

Function blocks and pins

A function block, that is, an object with pins, can represent an area, a partial plant, a sub-area, an aggregate, a section, or a component. Function blocks have attributes and function block pins have attributes.

The following figure shows a function block and its pins as they appear in the program view:

Function block attributes

The main attributes of the function block are:

  • Name: Name of the function block based on the key of the TD. Example: ThOvrld
  • Description: Additional description. For generic operation it is shown as text in an operator unit. Example: Thermoelectrical ovrld
  • Element type: Block in plant-engineering terms. Example: Component
  • Main value: Main value of the function block. It is set during engineering. Example: PrVal

Function block pin attributes

The main attributes of the pins are:

  • Name: Pin name, based on the key of the TD. Example: PrVal
  • Description: Description of the pin name. Example: Present value
  • Value: Current value of PrVal. Example: Normal
  • Parameter Kind: Application pin type. Example: Process input
  • Data Type: Data type of the pin. Example: Multistate

For a complete list of attributes, see CFC Online Help.