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Unistream alarm history - NOT retentive?

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using Unistream PLC (tested with or without HMI with 1.28.34 - the problem is the same) we note a strange behavior regarding Alarm History in Unistream and SD Card.

During normal operation all works well (events history is correctly display using the related HMI object and data are stored in CSV file into SD Card).

The problem is that It seems that after reboot, the Alarm History list is empty, so all the history is lost. We have seen that the PLC creates a CSV with the alarm history list, but after reboot also that CSV is empty (the file is there but inside there are no records).

In the SD AlarmLogs subfolder, there are other CSV files with a prior timestamps (probably with lost events but these data can not be seen with any HMI object).

Is there a way to make the Alarm History retained? If it erases itself after reboot, it is not useful…

We don’t think it is useful having an alarm history that does not keep the list on the HMI after reboot...

The customer needs to see the alarm history also after the reboot using the integrated HMI!

Thanks and Best Regards

Roberto Zeni


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Upon an Alarm event the data is saved in an internal buffer.  The trigger for the internal buffer flush is one of the below:
  - Using Action "Create and zip Alarm log"
  - Number of Alarms events on internal buffer is more than 64
  - 1m passed from an Alarm event (any event occur when this timer fire will be written as well)
You can use the action in case you want to save the logs in a higher resolution.

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Hi NoamM,

first of all thanks for reply!

The problem is not when the system saves the events but more simply the fact that, regardless of how the events are saved, when the PLC restarts these are no longer in the .csv file pointed to by the HMI object that allows you to view them directly from HMI.

In fact, the operator wants to see the data on the machine and it is not enough for him to export it and then see it on the PC ...

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There are two ways:

1) Do not delete CSV file at startup. In this way the operator will be see all old events directly on the HMI, The CSV file should be deleted only by a PLC command,

2) Modify the HMI object "Alarm Summary List" to manage the old Alarm log

In my idea it's easier the 1) way.

Thanks and Best Regards

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