In a GSD file a distinction is drawn between DP slaves with fixed and modular configurations.
DP slave with fixed configuration
In the GSD, a DP slave with a fixed configuration will show the entry
Modular_Station = 0
followed by one or more entries for modules of the type
Module = "module 1" 0x3F ; 16 inputs and 16 outputs
All modules listed are firmly integrated in the device and the user cannot modify their number or sequence in a fixed configuration.
DP slave with modular configuration
In a modular configuration the maximum number of modules is specified. In addition, the maximum amount of data is defined.
Modular_Station = 1 ; modular station
Max_Module = 4 ; max. 4 modules can be defined
Max_Input_Len = 100 ; maximum length of inputs
Max_Output_Len = 100 ; maximum length of outputs
Max_Data_Len = 200 ; maximum length of inputs and outputs
The modules listed are a selection and the user can make a specific choice here. In doing so, it is important not to exceed the number of modules, nor the amount of input or output data for the DP slave.
Module = "empty slot" 0x00
Module="2 Bytes Output" 0x21
Module="2 Bytes Input" 0x11
Module="6ES7 322-1BF01-0AA0 8DO" 0x83,0x00,0x00,0x2F,0xC8
This last module can then appear as follows in a configuration tool:
Alternatively, numerous identifiers can also be listed in a module. However, I cannot recommend this, because the assignment takes place of diagnostic messages to the identifiers and not to the modules!
Module="1 Byte Input / 1 Byte Output" 0x10 0x20