X20 system modules • Counter modules • X20DC1178
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X20 system User's Manual 3.10
Automatic acknowledgment of latched error states
In addition to manual acknowledgment, automatic acknowledgment of the latched error states after a specified
amount of time can also be enabled. Make sure that the time is set long enough for the higher-level system to
reliably detect the status messages and for the validity of the counter value to be determined using its age.
If the time specification = 0, then only manual acknowledgment is possible.
Example 1:
An error has occurred on a signal line. The error state is detected and latched by the module. The
time for automatic acknowledgment starts counting after the cause of error has been corrected.
The error is acknowledged as soon as the time expires. The latched error status changes to zero.
Error on signal line
Latched error state
Automatic acknowledgment
Time
start
Time
expired
t
t
t
Figure 265: Latched error state acknowledged automatically
Automatic and manual acknowledge used
Example 2:
An error has occurred on a signal line. The error state is detected and latched by the module. The
time for automatic acknowledgment starts counting after the cause of error has been corrected.
The error is acknowledged manually by the user before the time expires. The latched error status
changes to zero. The manual acknowledge must now be reset so that any new errors will be
recognized by the user.
Error on signal line
Latched error state
Automatic acknowledgment
Manual acknowledgment
After successful error evaluation,
the error is manually acknowledged by the user
Time
start
Time
expired here
t
t
t
t
Figure 266: Automatic and manual acknowledge used
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