Siemens SIMATIC ET 200S Operating Instructions Manual page 191

Acknowledgment Principle in Isochrone Mode
In isochrone mode, exactly 4 bus cycles are always required to reset the status bits and to
accept values during the load function.
Figure 3-33
Error Detection
The diagnostic errors must be acknowledged. They have been detected by the
1Count5V/500kHz and are indicated at the feedback interface. A channel-specific diagnosis
is carried out if you have enabled group diagnostics in your parameter assignment (see the
ET 200S Distributed I/O System
The parameter assignment error bit is acknowledged by means of correct parameter
assignment.
Figure 3-34
In the case of continuous error acknowledgment (EXTF_ACK=1) or at CPU/Master Stop, the
1Count5V/500kHz signals errors as soon as they are detected and deletes them as soon as
they have been eliminated.
Technological Functions
Operating Instructions, 02/2007, A5E00124867-05
Acknowledgment Principle in Isochrone Mode
Manual).
Error Acknowledgment
1Count5V/500kHz
3.7 Measurement Modes
191