Clocked Mode - Siemens SIMATIC ET 200S Operating Instructions Manual

1SSI

4.2 Clocked Mode

4.2 Clocked Mode
Note
The principles of isochrone mode are described in a separate manual.
See Isochrone Mode Function Manual (A5E00212909).
Hardware Requirements
You will require the following for the 1SS in isochrone mode:
• A CPU that supports isochrone mode
• A master or Profinet master that supports the equidistant bus cycle
• An IM 151 that supports isochrone mode
Features
Depending on the system parameter assignment, the 1SSI works in either non-isochrone or
isochrone mode.
In isochrone mode, the data exchange between the master and 1SSI is isochronous to the
bus cycle.
In isochrone mode, all bytes of the feedback interface are consistent.
If isochronous mode fails, the feedback interface is not updated. In the user program, this
can be detected with the sign of life in the feedback interface.
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Technological Functions
Operating Instructions, 02/2007, A5E00124867-05