PROFINET device concept

PROFINET distinguishes between the controller and its assigned devices. These are initialized and parameterized by the controllers on power-up. The controller and its devices together constitute a PROFINET I/O system (compare master/slave system for PROFIBUS).

For PROFINET, cyclic communication between an IO Controller and its IO Devices is performed in the same way as for PROFIBUS over the process image. The process image is updated cyclically. Depending on the requirements and device characteristic, this takes place in real-time (RT, devices are typically distributed IO Devices) or isochronous real-time (IRT, devices are typically servo drives). Further, PROFINET permits communication between the controllers and devices of different IO systems.

PROFINET IO with RT for simple standard drive applications

With typical cycle times between 4 ms and 10 ms, PROFINET IO with RT offers the same performance characteristics as PROFIBUS as regards cyclic data transmission.

With this performance level, all standard drive applications belonging to PROFIdrive application categories 1 to 3 can be automated, i.e. those categories requiring the specification of speed, torque and current setpoints or target positions which do not need to be linked isochronously.

PROFINET IO with IRT for Motion Control¹⁾

In this case, a Motion Control system controls or synchronizes axes using the PROFINET network. This requires cyclic, isochronous data exchange with the drives. PROFINET IO with IRT fulfills this requirement. The communication cycle is subdivided into different, time-specific channels for this purpose. The first channel is used for isochronous real-time communication (IRT), followed by real-time communication (RT) and standard TCP/IP communication. By appropriately configuring the application, e.g. a synchronous relationship between axes, IRT telegrams are implicitly determined and the appropriate configuration data generated.

The optimum time sequence of the individual messages for each network section is calculated with a special algorithm which takes the topology into account. This means that the switch is in a position to transfer the IRT telegrams without delay from the input port to the defined output port and then to the target device.

Transition from PROFIBUS to PROFINET

The functional interface between the controller and the SINAMICS drives for PROFINET and PROFIBUS is defined by the PROFIdrive V4 of PROFIBUS International. It is not necessary to change an user program for transfer from PROFIBUS to PROFINET.

PROFINET with PROFIdrive

Motion Control concepts with PROFINET

With SINAMICS, PROFINET supports the implementation of different automation structures. Distributed drive-based motion control concepts or central architectures with a control are supported in the same way as distributed automation solutions with modular automation components.

PROFINET – interface on SINAMICS

• SINAMICS S120 with a CU320-2 DP Control Unit and a CBE20 Communication Board
  The CU320-2 DP Control Unit on SINAMICS S120 is linked to the PROFINET IO network via the CBE20 Communication Board.
• SINAMICS S120 with a CU320-2 PN Control Unit
  The CU320-2 Control Unit on SINAMICS S120 is linked to the PROFINET IO network via the on-board PROFINET interface.
• SINAMICS S120 with a CU320-2 PN Control Unit and a CBE20 Communication Board
  The CU320-2 PN Control Unit on SINAMICS S120 is linked to the PROFINET IO network via the CBE20 Communication Board.
• SINAMICS S120 with a CU310-2 PN Control Unit
  The CU310-2 PN Control Unit on SINAMICS S120 is linked to the PROFINET IO network via the on-board PROFINET interface.

¹⁾ IRT interpolation with SINUMERIK NCK coming soon