04-19-2012 09:37 AM
I am trying to shorten the time that it takes for my current data to display on my digital meter. Currently the data is updated every 3-4 seconds. I would like to see it in real time. I have experimented with sample rate and different block sizes without any success. My system includes a PersonalDaq 56 coupled with Dasylab software. I am only utilizing one channel to capture voltage, the data is sent to a scaling module and then to a digital meter in addition, I have another digital meter that is connected directly to the output of the data logger. Any assistance will be greatly appreciated.
04-19-2012 10:00 AM - edited 04-19-2012 10:01 AM
The only way to improve the sample rate is to disable the calibration option and then to change each input channel to have a shorter sample duration.
When using the PersonalDAQ56, the sampling rate is determined by several factors. In the Measurement setup for the device, you can select the auto-calibration mode and the overrange protection. The calibration mode takes time at the start of measurement before the first sample is collected and periodically during the measurement.
Then... the actual sample rate maximum depends on the measurement duration (per channel, set in the Analog input module) and the sample rate (set in the Measurement setup for the device).
Measurement duration (per channel) – the amount of time used for sampling a channel’s input signal.
You can independently set the measurement duration for each channel. The measurement durations for
Personal Daq’s analog channels range from very slow (610 milliseconds for one sample) to very fast
(12.5 milliseconds for one sample).
Sample rate – Samples per second. The sample rate is the number of samples that take place per second.
With the very slow measurement duration of 610 milliseconds, there will only be 1.6 samples per second.
With the very fast measurement duration of 12.5 milliseconds, there will be 80 samples per second.
04-19-2012 10:30 AM
Been along time since we last talked, Thanks agin for all your help getting our software program up and running. Our new adventure is reading smoke from our smoke generator. I am trying to get the readout to update faster and speed up our test runs. It makes it a lot easier to run the equipment if you can see the changes in real time without the 3-4 second lag time. I have made a new worksheet with only the PersonalDAQ module and a digital meter module to try to figure this out. Currently I have the sample rate at 40 msec, I've turned off the auto calibration and the overrange protection but nothing seems to help. I have used the PersonalDAQ software to see if my PC is the issue, it seems to work just fine but I could not find any scaling capabilities so that is not an option for us. If I can get the data to update once per sec I would be very happy. What would you suggest I try next. Thanks