Concepts for the integration of INTERBUS in PROFINET IO
The combination of INTERBUS and PROFINET IO only contributes towards increasing productivity if the overall solution is seamless and uniform without losing the specific advantages of the fieldbus and Ethernet systems. It is for this reason that the integration of INTERBUS in PROFINET IO is based on the familiar proxy concept from the Internet. The network transition is realized with gateways that take on the role of a representative, thus guaranteeing that devices and objects connected to INTERBUS are integrated seamlessly in the PROFINET concept.
Taking the PROFINET IO device model, the following concepts for the integration of INTERBUS in the Ethernet standard are possible:
Transparent integration
Each INTERBUS device is mapped to a virtual IO device. The advantage of this is that all the devices connected to the fieldbus system are directly visible in PROFINET IO. It is, however, necessary to send a separate Ethernet frame with at least 64 bytes for each IO device even though INTERBUS devices generally only have very little process data. In the case of large-scale lower level systems, this leads to a high network load in the PROFINET system and thus to lower protocol efficiency. The transparent model is therefore not absolutely suitable for the integration of INTERBUS.
Compact integration
The entire INTERBUS system is mapped to one IO device with just one module and one submodule. Since it is possible to transmit the entire process image available via INTERBUS with a PROFINET IO telegram, the network load in the PROFINET system is low. The structural representation of the INTERBUS system, however, is not possible, since the INTERBUS devices are no longer visible in the PROFINET IO. In addition, it is necessary to plan the INTERBUS proxy with a special engineering tool.
Modular integration
Each INTERBUS device is mapped to its own module in just one IO device. It is thus possible to transmit the data of all modules in an Ethernet frame, resulting in high protocol efficiency in the PROFINET system. The characteristics of the INTERBUS devices continue to be available in the particular submodule. Another advantage is the fact that no extra configuration tool is needed for the INTERBUS proxy, since configuration of a modular device is supported by all programming systems.