Event Marker > Special Considerations
Event markers are saved to disk along with A-D data. Any event marker comments that were provided ride with the data acquisition file as a trailer (see also Data Storage Format).
Event markers may be enabled either locally (manually) by pressing the appropriate accelerator key (as in the Example), or remotely through a switch closure or TTL signal. Refer to Remote Control for details related to remote triggering of event markers.
An event marker is automatically inserted in the data stream each time the RECORD operating mode is activated. An event marker created in this manner is always tagged with a time and date stamp that allows any point in a recorded waveform file to be correlated with a precise date and time of occurrence (to the nearest second). Refer to the SEARCH-FOR-EVENT function of the WinDaq Waveform Browser Help File for further information related to viewing and using time and date stamp information.
WinDaq Acquisition allocates 4 bytes of Global DOS memory per entry for event marker, time and date stamp, and comment information as follows:
The total number of entries per manual start for items 1 through 4 above is configurable by Edit > Preferences > Event Marker Capacity…. Note: Starting with WinDaq Acquisition Version 3.01 this menu item is not available/necessary since the capacity is only limited by available disk space - the information is written to side files. This menu item is available in all Windows 3.1 versions and for parallel port DI-200/300 software under Windows 95 and 98. See also Event Marker Capacity.
These numbers may be used as follows to calculate the total number of event markers of any type that may be used per manual start: Divide the capacity less 2 by the number of entries required for each event marker operation. For example with the maximum configuration of 16,384 entries, if all event markers enabled by you during data acquisition are without comments, then a total of 16,382 may be activated between an un-commented manual start and the subsequent stop. A total of 8,191 may be activated with comments only or with remote start time and date stamps only. The actual comments you enter are contained in separate memory and therefore consume only one entry apiece, and each manual start produces at least one event marker with a time and date stamp activated automatically by WinDaq Acquisition upon the initiation of waveform recording to disk.