SignalExpress
cycle count
Hi J.B.,
Sorry for the confusion, I guess I should have explained the reasoning behind my choice of value for the samples to read. I chose 4000 samples to read as a demonstration based around your requirement of logging only 10 cycles out of every 4000. I configured 4000 samples (which equals out to 40 cycles of a 1Hz waveform sampled at 100Hz) so that when those 40 cycles were collected the Subset and Resample step could extract a single cycle out of that set. For your application you would need to configure 40000 samples to read to get 400 cycles per read iteration, but this would take 400 seconds before the data view plot would update, per iteration!
The "number of periods" calculation takes place after every read happens, so the log file would need to be parsed afterwards to sum all of the period measurements together (because LV SignalExpress is not flexible enough to do this).
A new header is created on each iteration currently because we are writing the Subset data to the log file on each iteration, and it thinks of the subset data as a new waveform with new timestamps.
If the "number of periods" calculation is a more critical piece of information to have, I think you will have to sacrifice and acquire all the cycles rather than 10 out of every 4000.
I guess the overall conclusion here is that LV SignalExpress may not be flexible enough to give you the results you are trying to get. SignalExpress is intended to provide the ability for simple data acquisition and logging applications, but LabVIEW may be a more suitable development environment based upon your requirements. If you have LabVIEW at your disposal I could make some recommendations that could get you up and running pretty quickly.
Regards,
Andrew
Sorry for the confusion, I guess I should have explained the reasoning behind my choice of value for the samples to read. I chose 4000 samples to read as a demonstration based around your requirement of logging only 10 cycles out of every 4000. I configured 4000 samples (which equals out to 40 cycles of a 1Hz waveform sampled at 100Hz) so that when those 40 cycles were collected the Subset and Resample step could extract a single cycle out of that set. For your application you would need to configure 40000 samples to read to get 400 cycles per read iteration, but this would take 400 seconds before the data view plot would update, per iteration!
The "number of periods" calculation takes place after every read happens, so the log file would need to be parsed afterwards to sum all of the period measurements together (because LV SignalExpress is not flexible enough to do this).
A new header is created on each iteration currently because we are writing the Subset data to the log file on each iteration, and it thinks of the subset data as a new waveform with new timestamps.
If the "number of periods" calculation is a more critical piece of information to have, I think you will have to sacrifice and acquire all the cycles rather than 10 out of every 4000.
I guess the overall conclusion here is that LV SignalExpress may not be flexible enough to give you the results you are trying to get. SignalExpress is intended to provide the ability for simple data acquisition and logging applications, but LabVIEW may be a more suitable development environment based upon your requirements. If you have LabVIEW at your disposal I could make some recommendations that could get you up and running pretty quickly.
Regards,
Andrew
