Getting Started with the Q.gate DP Controller

Guide to initiating the Q.gate PD controller with Profibus DP interface.

Maximum total data size

The Q.gate PD supports a maximum total data size as follows:

  • 244 bytes for INPUT data
  • 244 bytes for OUTPUT data

If either of these limits is reached within the process image of the controller, the data overhead on Profibus will be automatically cut off, and only the maximum possible data size will be transferred. In such cases, test.commander will display a warning message.

Compatibility Mode

As a result of essential alterations in the Profibus implementation within the controller firmware, the maximum size of transfer data on Profibus can vary across different firmware versions. Consequently, a "compatibility mode" has been introduced to switch between the old and new implementations, offering users flexibility in their selection. 

The Compatibility Mode parameter is accessible with:

  • test.commander versions equal to or greater than 1.8.0
  • Q.gate DP firmware equal to or greater than 0.67


Compatability Mode "old"

By using this mode, the old Profibus implementation is activated, which mirrors the implementation found in Q.gate DP firmware versions less than or equal to 0.64. The maximum data transfer size is:


Compatability Mode "new"

In the new Profibus implementation, an error that could arise with certain new Profibus master systems has been rectified. Consequently, it was necessary to reduce the maximum possible size of transfer data. The maximum data transfer size is:


GSD file

GSD files contain essential information regarding a module's capabilities. With a GSD file, system integrators can ascertain fundamental details such as communication options and available diagnostics. These files adhere to a standardized format outlined in the Profibus guidelines. The GSD files for modules are typically located in the ICP 100 program directory (C:\Users\Public\Documents\Gantner Instruments\ICP100\GSD), or they can be downloaded from the Gantner Instruments website:

For the Q.gate DP controller you need the following GSD files: GANT6783.gsd

Important Notes:

  • As all Gantner Instruments controllers and modules are modular, the provided GSD files are also modular. This means that the GSD files do not map a complete process image of a system; instead, they contain a set of possible configuration bytes. It is essential to represent the process image of a controller 1:1 in the Profibus master to ensure communication.

  • The GSD file contains an "Ident_Number" used to establish a reference between a slave and its corresponding GSD file. This number, assigned by the Profibus Trade Organization, cannot be changed and serves security purposes. Every Q.gate DP controller has the same Ident Number, so it is impossible to have multiple GSD files in one master system with the same Ident Number.

  • Certain Profibus masters, like Hilscher with SyCon Software, can automatically read the configuration of the slaves on the bus. However, other masters, such as Siemens STEP 7, cannot do this. In such cases, the process image needs to be manually rebuilt in the master software according to the Profibus representation of the system.


Profibus Representation

The Profibus-Representation of the transferred data of a Controller can be found in the *.CSV file of the test.commander project, in the corresponding project directory.