User`s manual

APPENDIX A - DATA LOGGER A-2
CDS7324 (FORMERLY LSF-0819)
Rev. A INSTALLATION & USER’S MANUAL
A.1.2 Time base
The data logger normally runs at the main interrupt frequency of the controller (PWM frequency) or a fraction of
this. The main interrupt frequency can be read with the parameter data_logger_sample_frequency (field number
1751). The divider ratio can be set with the parameter data_logger_divider_factor (field number 1750). The
resulting sample frequency is then data_logger_sample_frequency / data_logger_divider_factor.
A.1.3 Trigger
The trigger controls the sampling of the data syncronized to a trigger input which can be any of the 8-, 16-, 24- or
32-bit integer or 32-bit or 64-bit floating point parameters. It is possible to have a delayed trigger or pre-trigger.
The possible trigger coupling can be dc, ac or bitmap masking, the slope can be rising, falling or both.
A.1.3.1 Trigger modes
The parameter trigger mode trigger_mode (field number 1755) controls the trigger and the sampling. There are
four different trigger modes available:
0x00 - free running trigger: always sampling
0x01 - normal trigger: waiting for trigger event and start sampling,
retriggerable after sampling has finished
0x02 - single shot trigger: after trigger event only one set of samples taken
0x03 - stopped: no samples taken
A.1.3.2 Trigger status
The actual trigger status can be read back reading parameter trigger_status (field number 1767). It has one of the
four possible values:
0x00 - system is being initialized; data logging not possible
0x01 - waiting for trigger event
0x02 - sampling
0x03 - ready, sampled data can be accessed
The samples can be only read from the data logger memory when the trigger status is ready. In single shot
triggering the data logger will go automatically into the ready state. In free running mode or normal trigger mode
the data trigger mode has to be set to stopped. After finishing the sampling, the data logger will then automatically
go into the ready state.