DP Identification

The DP identification in WinCC OA (shortly DP Id) is a unique internal identifier for data point types, data points, configs etc. The identification is mandatory when accessing DPs via CTRL or from a user interface. The DP Id of the systems is also exchanged when configuring a distributed system. The Id is exchanged to be able to use the DPs on foreign systems (see also Principle and functionality of distributed systems). The Data Manager administers the identification. Each manager gets the identification from the Data Manager when starting. (Exception: when using a local identification the DP Id is saved in files - further information concerning the local Id is given later on this page).

Each DP of a system is accessed in WinCC OA internal via a number instead of the name for performance reasons. This number is the DP identification (= Id). The names are converted internal to Ids via tables. The following information is used when converting the names:

• Data point types: There is an internal table per DPT. This table contains the name of types and elements.

• Data points: There is an internal table with the name per DP.

• Data point elements: There is an internal table per DPE. The table contains the description, unit, format and alias.

• System name

• Config and attribute names (these are fixed and not changeable in the project)

In bigger projects, of course, also the DP ID is bigger and can be up to several MBs. The access to DPs (e.g. with CTRL) would not be possible without this Id.

WCCOAtoolNameToId

Use the tool WCCOAtoolNameToId to determine the data point ID using the data point name and vice versa. Start the tool via the Shell of the operating system. The command has the following syntax:

C:\>WCCOAtoolNameToId -proj <projectName> <SystemnName>:<data point name>

or

C:\>WCCOAtoolNameToId -proj <projectName> <systemNumber>.<data point ID>.<element ID>

Figure: Example of a Shell command with specification of the data point name and the DP ID

The information is displayed in the WinCC OA log viewer, when the project is running, or is written to the WCCOAtoolNameToId1.log file of the /log directory of the WinCC OA project.

The following is displayed according to the input order above:

Type: 37 Sys: 1 Dp: 93 El: 0 : 0..0)

whereby Sys: 1 indicates the system number and Dp: 93 indicates the DP-ID.

System1:ExampleDP_BarTrend

Independent of whether the data point name or the ID is prompt in the Shell, the system number has always to be passed.

Caution

When using WCCOAtoolNameToId on Solaris, WinCC OA has to run complete or has to be stopped and the Im_ip has to run.

NOTE

Stop the tool by pressing Ctrl + Z.

Local identification

Specific for slow connections (e.g. remote UIs via modem connection) is the start phase of a manager when the whole ID is transferred. In bigger projects the start phase is sometimes very long. To improve this the Id

can be saved on the local computer. There is the following config entry for using the local Id:

When the manager starts the first time (the manager for which the config entry was set) the Id is transferred by the Data Manager (since the files for the local Id are not created at this time). When the manager runs it

processes normally all changes. When stopping the manager writes the current Id in the DpMsgTypeContainer.bin and DpMsgIdentification.bin files. These files are at last saved in the directory <proj_path>/data.

Another start of the manager does not transfer the Id from the Data Manager anymore but reads it from the local disk. For example DPs, which were created/deleted with an UI that doesn't use the local Id, are not present anymore (if the UI with the local Id was stopped while creating/deleting DPs and afterwards started, i.e. the local Id is not updated). In order to get the current Id again the manager has to be stopped, the files have to be deleted and the manager has to be restarted so that the current Id is transferred by the Data Manager.