Historical Trendview Data Logging Interval
Hello,
I am using a BX08-NTC module and I am using historical view to look at data recorded with it. (I am not using the "record button", just looking at the graph). I have noticed that the data is being logged to historical view every ~1.75 seconds. Is there a way to change that to have a better resolution? "Export/Logging Method" is set to 200ms. Historical Data to retain is set to 1Mb. Thanks.
When you select Export from the Trend View, one option is to save it at a timed interval - possibly that's what you selected? You can specify any time interval with millisecond resolution. The other option is to save it as the values changes (this is how the data is actually recorded and stored internally in the Trend View).
"Record" does not give you this option - it records at about 1 second interval.
I am not exporting yet, just using the TrendView graph to view. Does the logging setting only affect the exported data or does it affect the graph too? I have the logging set to 200ms. But all sensors are reading ~1.75 seconds. Thanks for help!
It affects the logging data - not the trend archived historical view. The view shows the data. If the data is stamped at every 200ms, that's what it shows. If the data is stamped is every 1000ms, that's what it shows. If it was based on data changing, there is no interval, but the data is plotted basically "real time" stamp.
Not sure what you are seeing. Also, if you haven't exported, how did you get that import? Maybe when that file was exported, the interval was different?
I recommend trying it with your own export that you generated, based on your settings (200 ms).
I just exported the data and it shows that same temperature for 8 points (every 200ms). Then the temperature jumps and then the same data is then recorded again every 200ms. These are NTC sensors, so is an analog signal and read by the BX08-NTC. I would expect that the temperature would be variable/continuous, instead of being exactly the same for every 8 recordings and then changing. An example temperature step I'm seeing is 5.3 degrees C. The temperature can't be staying the same for 1.6 seconds, and then jumping 5.3 degrees in 200ms, to stay the same for 1.6 seconds and jump again. Is there some setting in the BX-08-NTC module that can be adjusted?
BTW, before I exported, I did not have an export. The image was just a screen shot of historical data in Trendview.
Thanks for helping me with this.
My bad. I misunderstood your initial post.
The module itself does have its own internal cyclical processing. If you are using all 8 channels, I bet that slows down its processing.
Looking at the spec here
BRX Expansion Module (BX-xxNTC)
it says 2.2s is "all channel update rate @ 16.7 Hz, internal channel sampling rate).
So it appears the module is slower than the PLC scan, or even the Designer Trend View comm data update rate. Not sure how that gets processed relative to the 200ms detents you are seeing. I know temperature processing is slow.
If you require faster update rates, you might look at getting a couple of the 4 channel Universal Temperature modules BX-04UT with a "all channel update rate" of 700ms:
BX-xxUT
(the 8 channel version is 1400ms, hence why you might consider two 4 channel UT modules for the faster update rate, if required).
But if you are just trying to understand the 200ms detent on the Trend View, temperature module internal processing is just slow compared to the PLC scan. 🙂