DT800 timing and synchronization

The DT800 is a high speed logger capable of bust mode sampling to 100 kHz.

DT800 timing and synchronization

Postby anton » Wed Apr 19, 2017 6:37 am

I am repurposing several DT800's and my trials sofar indicate that they will be able to do a great job. But not everything is making sense to me.

To put things in context, I would like each logger to measure between 10 and 20 voltage signals, once per second, within the first 50 ms, and the loggers synchronized to within 10 ms of each other.

1) I figured out that the timestamp on the data records is the time before the measurements. I also figured out that I can get additional time stamps by adding "T" columns to see how long the measurements are taking. At one point these T columns were displaying millisecond resolution, but now I can't get anything better than one second. How can I control this? I must have changed something, but I can't figure out what!

2) I managed to tweak P46 and P60 to get more or less channels read in a short period of time, but when I try to use these values witht he FAST mode modifier, I do not get the same result at all. The schedule runs a fraction of the previous speed. Is there any other difference with FAST mode, other than the values of those three parameters? If I put in the values corresponding to Normal mode, should Fast mode run just like normal mode?

3) The default ADC rate is half of the maximum rate. What is the downside of going faster than the default rate? Is there an advantage to going slower than the default rate?
anton
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Re: DT800 timing and synchronization

Postby Rudy Gunawan » Tue May 02, 2017 12:37 pm

Hi Anton,

You must have accidentally set P41 setting to 0.
P41 control sub second digit, default value is 3.

Can you explain the different on FAST modifier?
FAST syntax definitely will modify P11, P46, and P60.
You may modify those setting without declaring FAST to get the same result on NORMAL mode.
Please note the last setting that get affected by FAST syntax is P57.

ADC frequency is related to internal channel conversion if available (i.e.: when reading temperature sensor, current sensor).
Faster ADC speed will limit the option into voltage as using other signal will eventually override the frequency setting.
Please check this link for full explanation on ADC: http://www.datataker.com/Datalogger_Man ... Timing.htm

Best regards,
Rudy Gunawan
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