FAQ#083 – How does the TRIGGER function of OMNIAlog digital input work?

The TRIGGER function of the two digital inputs available on OMNIAlog datalogger is typically used with seismic station. In case of an event (earthquake), the seismic station is usually able to supply a certain tension on its output (typically 5Vdc). If this output is connected to the digital input of OMNIAlog, and OMNIAlog is conveniently configured, the extemporaneous acquisitions of all the sensors connected to OMNIAlog will be done (the number of acquisitions is programmable on OMNIAlog web pages). This way, after an earthquake, it is possible to compare the readings of the instrumentation connected to the two dataloggers. Therefore, it is no necessary to wait for the planned acquisitions that could take place several hours after the earthquake.

In case the extemporaneous reading generated from the digital input overlies the planned reading, this one will be done at the end of the “extemporaneous acquisition”.

In case there are different “extemporaneous acquisitions” that overlie the planned acquisition, this one has the priority. Therefore, at the end of the first extemporaneous acquisition, the planned acquisition will be done. At the end of the planned acquisition, the remaining extemporaneous readings will be executed.

The extemporaneous acquisitions are read as “normal” acquisition from OMNIAlog. Therefore, the planned alarms are notified and the acquisition is saved in OMNIAlog memory.

In events log, the event linked to the extemporaneous acquisitions appears, in order to identify them.

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