Double logging on the Licor on one of the flux towers

[philrosenberg]

One of the Licor instruments has some double logging going on. It seems that every data line is being logged twice. But filtering the data is not trivial as there are also occasional corrupt lines/missing lines and this messes up just discarding every other line.

I can't remember offhand if it is tower 1 or 2, so I've flagged both.

[philrosenberg]

Due to Covid I couldn't get the tower back before it was needed to be redeployed by the same group (at Kings).

My best guess was that maybe the logging software was set running twice, but I don't really know. I have adapted my code to filter the data as it has an id value that increments by a certain number each line (15 if I remember correctly) so I can identify duplicates.

I'll have to look in more detail once the instrument is back.

[philrosenberg]

The corrupt lines issue was due to the licor sending out data with LF line endings, but the logging code expecting CRLF line endings. Both licor instruments have now been set to use CRLF line endings and corrupt lines have stopped.

[philrosenberg]

The double logging issue is with Licor 1 only. It appears that it is outputting data on the rs232 interface at 20 Hz, even when it is told not to output data at all. Then when it is told to output data, it duplicates the relevant lines. For example, when set to output at 20Hz, it outputs every line twice, giving 40 lines of data per second. When set to 10 Hz, it duplicates every second line outputting 30 lines of data per second. When set to 1 Hz it duplicates just one line of data per second.

Now that the actual details of the problem are known, it is easy to filter existing data. because we know we actually want 20Hz data, we can set the data rate to 0 Hz and get the 20 Hz, or we could set the data to 20 Hz and filter out the duplicates.

I am going to set the box to 20 Hz, because if we set to 0 Hz and the fault somehow fixes itself, then data will stop. But if we set it to 20 Hz and the fault somehow fixes itself then we will still get 20 Hz data.

[philrosenberg]

I emailed the manufacturer about the problem. The attached files were sent to them showing examples of the repeat data
05Hz_test.txt
10Hz_test.txt
20Hz_test.txt

[philrosenberg]

Manufacturer recommended a firmware update, but this was postponed until after the existing project completed.

[philrosenberg]

Firmware version on Licor 1 (find it through the software on the Dagnostics section) is:
Embedded 7.3.1
DSP 4.3.9
FPGA 6.0.3

Downloaded the latest firmware from the licor site https://www.licor.com/env/support/LI-7500RS/software.html, grabbed the win-GHG (LI‑7500A/RS) firmware v8.9.0, unziped the zip file and ran the exe. A memory stick was needed - plug this in the usb port when you open the LI-7550 box. It uses this as some sort of cache during install I think.

When I tried to reconnect to the licor from the laptp it said I needed to update the laptop software so I did - this was on one of the energy balance laptops. This was updated to 8.9.2.

Rebooted laptop - attempted to connect to the licor - got this message:

But the software still connected. after disconnecting and reconnecting the software connected fine - in between that I also set the windows time server as it was set to a 192.xxx.xxx.xxx local timeserver and the laptop time was 15 mins out - I wondered if this might be contributing to the error.

[philrosenberg]

Checking all combos of instrument,, interface units and loggers, to isolate the problem.

Logger1, IU1, instrument1 ; double logging
Logger2, IU2, instrument2: no double logging
Logger1 IU1 instrument2: double logging
Logger2, IU2, instrument1 no double logging
Logger1, IU2, instrument1 double logging
Logger2, IU1, instrument2 no double logging
Logger1, IU2, instrument2 double logging
logger2, IU1, instrument1 no double logging

So it turns out it is the logger's fault, not the instrument.

I have diff'ed the /home directory on the two loggers and ensured they are identical. I have copied the /home directory from logger2 into logger1 to be sure. I'm still seeing the same problem.

James and I have scratched our heads over this a lot and we can't find the solution. Checking the licor manual (appendix D) there is an rs232 command to grab an immediate packet and also toggling the "request data" line of the rs232 will force the generation of an immediate packet. I can only think that we have something like this happening, but as I didn't build the system, I have no idea how.

The data can be filtered to remove the duplicates, so that is what we will have to do.