Module-Defined Data Type Format
When you create a module, module-defined data types and tags are automatically created. These data types define the structure of the data used by the module for its Input, Output, and/or Configuration Data. These tags allow you to access this data via the controller’s ladder logic.
The module-defined data types (or tags) that are created vary for each module. In addition, within a specific module, there is also variation among the data types that are created, depending on the Communications Format (Comm Format) you choose when creating the module.
For each module you create, specific instances of these data types are created and named according to the selected Comm Format. You can view these tags in the Tag Editor/Data Monitor. You can also reference them in logic.
For example, the 1756-IA16I module has four Comm Format choices:
- Input Data
- CST Timestamped Input Data
- Listen Only - Input Data
- Listen Only - CST Timestamped Input Data
If you choose CST Timestamped Input Data, different tags are created than if you choose Input Data.
Module-defined data types can be nested within other module-defined data types. User-Defined data types reference module-defined data types.
Module-Defined Data Type Format
The set of tags associated with any module depends on the type of module and the Comm Format you choose when creating a module. These tags contain a set of module-defined data types according to the following format:
<Vendor>:<Module_Specific_Identifier>:<Tag_Type>:<Version>
<Vendor> | AB for Allen-Bradley . |
<Module_Specific_Identifier > | Contains module family information, module type, number of points/channels, and information identifying the format of the data type. For example, the module-defined data type, "AB:1756_AI6_Float:I:0" would represent a 1756 six-channel analog input structure applicable when the module is configured to return floating point data. |
<Tag Type> | Specifies whether the data type is used as an input, output, or configuration tag (e.g., 'I’, ’O’, or ’C’). For modules in which the configuration data is exposed, a data type with a tag type of ’C’ (for Configuration) is created. For Input modules, a data type with a tag type of ’I’ (for Input) is created. For Output modules, a data type with a tag type of ’O’ (for Output) is created. For modules in which the status data is exposed in a separate tag, a data type with a tag type of 'S' (for Status) is created. |
<Version> | Numeric value indicating the version of the data type. |
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Information on module-defined data types for specific modules is contained within this Logix Designer Online Help system. If you choose Contents from the Help menu, and then click the Index tab, you can find this information by typing "module-defined data types" in the search field, and then scrolling down to the module in which you are interested.
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