Examples of the CTT2 Data Exchange Request/Response service

Access to the drive parameters of the decentralized inverter via the CTT2 "Data Exchange Request/Response" service is explained in more detail with a few examples.

A sample project can be found on the SEW‑EURODRIVE website (www.sew-eurodrive.com). Select [Online Support] > [Data & Documents] > [Software] and search for "TIA sample project".

The following figure shows the general process:

[1]

PLC

[2]

AS‑Interface master

[3]

B device

[4]

Data Exchange Request message – This is sent to the B device with the parameter access data.

[5]

Cyclic data exchange

[6]

Acyclic parameter communication from the AS-Interface master to the B device consisting of:

  • 4 byte CTT2 service
  • 12 byte SPA Request message

[7]

Data Exchange Response message – This is sent to the AS-Interface master after the SPA Request message has been processed.

[8]

Acyclic parameter communication from the B device to the AS-Interface master consisting of:

  • 1 byte CTT2 service
  • 12 byte SPA Response message

[9]

Data Exchange Response message – Contains the result of the parameter access in the SPA Response message.

Additional information