Blog from November, 2009

18Nov09  Site Visit: CG, KK, JM

- Purpose: Install 5 Licor 7500's

- Power: We rearranged the power / batteries to accomodate the licors.   A high current/trickle/equalize battery charger was connected directly to the battery chain and not through the solar/battery charge by using the last 'external battery' amp connector.   This was because an excessive feedback impedance from the Morningstar charge controller was causing the commercial battery charger to not see the proper battery voltage preventing it from starting up to supply the loads (ie battery charger was 'too smart').   A regulated, current limiting supply wouldn't care and could be cranked up to a voltage more closely approximating solar panels (ie 14-15vdc).   There are now 3 batteries in the string.   A power distribution Tee was connected to the 'fused load' of the primary battery box with one secondary going to the Adam and the other going to the 5 Licor chain.   The licors are being powered directly because earlier tests showed that the voltage drop in our smaller gauge isfs serial cables was excessive and causing the higher-level licors to not have adequate supply voltage.   The internal solar-battery-charger is being used only as a 'low-voltage-disconnect' switch for these 2 loads.    

- Licors Installed.   The 43m,30m serial cables had been added before, so we only installed those for 2.5,7.5,15m

- Licor Ingest Problems: After installing the licors we observed many 'spurious interrupts' on the adam console.   These were caused by the licors, especially at 43, and 15m, but those were not the only ones.   At first we thought the cables may have been 'funky' and tried removing some cable ties to no avail.   When we disconnected the worst offenders, the adam was able to do a data_stats and the statistics for the licors looked ok, as did the console rserial printouts.   However the diamonds/adam was having clear difficulty.   Gordon was able to login to the system and reprogram a few of the sensors to try to slow them down to overcome these interrupts, and although at first it appeared that worked, it did not.    .... Pow-wow time.   I'm suspecting a power/serial ground issue combined with the serial driver circuit on the licors, although the diamond boards may be culpable.   It is noteworthy that there are 2 different diamond boards involved in these.   We left the system running but with the 15 and 43m licors disconnected.

Here are my notes from this week on the first servicing we've ever done on our Li7500s.

Note that S/N 0813 and 1166 came back from LiCor this summer after being repaired (from lightning damage), so no service was performed on them.

The following all was done using LiCor's software (installed on the Aspire).  Before service:

On the afternoon of 10 Nov 09 (after Chris&Jen recovered them from MFO), I dumped the dessicant/scrubber (Magnesium Perchlorate; Ascarite2) from the bottles of 1163, 1164, 1167 and replaced with new Drierite and Ascarite2, following the manual instructions.  I put a sticky label on one bottle in each sensor with this replacement date.  Instructions say to have the sensors run for at least 4 hours before proceeding with calibrations, so they were all left overnight powered on.

On the afternoon of 11 Nov (~23 hours after changing chemicals), we went through the calibration procedure using a cal lab nitrogen tank for zero CO2 and H2O and a tank I borrowed from Teresa Campos/Cliff Heizer at 404.316ppmV for span CO2.  Both of these were supplied to the 7500 using the LiCor calibration tube at a flow rate of about 1.3 lpm.  Span H2O was achieved by placing the entire 7500 head in the Thunder chamber at T=25C, RH=80%, which should be a dewpoint of 21.31C.  Since the electronics box was outside the chamber, the calibration tube was also placed in the chamber (though not in the optical path) to measure pressure.  Since it seemed to take a long time (25 & 50 min, respectively to calibrate 1167 and 1163), we used the calibration tube's temperature reading when we calibrated 1164 the next day.  This sped things up a bit. The calibration in the Thunder took long enough that 1164 was done the next morning.  The new readings were:

AGC values were not logged, but noted to be within 1% of the earlier readings (even with the tube on).

With one exception, these values are higher than before service, indicating more absorption now.  I note that I didn't clean the optics prior to this calibration, which probably should have been done, but spot checks of a few of the sensors looked pretty good.

Chris also ran 0813 and 1166 into the chamber (with a dewpoint still at 21.31C) and found that these sensors showed dewpoints of 22.07C and 21.45C, respectively.  I'm a tiny bit concerned about this value from 0813.

Note that the LiCor software changed the instrument settings.  They will be reset before (re)deployment at MFO.

Nov 9, 12:30 MST.

Per Steve Oncley, increased the sampling rate of the Licor 7500 at 43 meters.
It is the only unit connected right now.

Commands to change the sampling rate:

# shut down data process
adn

# adn powers off port 17, power it back on.
eio 17 1

# start minicom
# The default baud rate of minicom on that port is 9600, which is what the 7500 
# uses after it is sent a break. To set it to 9600 explicitly, use ctrl-A pe.
# Use ctrl-A minicom commands to turn on local echo (e), line wrap (w) and send a break(f).
# Set bandwidth to 20 and RS232 output frequency to 20.
# Set terminator to 0A (newline):

minicom ttyS17
ctrl-A pe
ctrl-A e
ctrl-A w
ctrl-A f
(Outputs (BW 20) (RS232 (Freq 20.0)))
ctrl-A f
(Outputs (RS232 (EOL "0A")))
ctrl-A f
(Outputs ?)
ctrl-A q

# minicom should now be finished

# power off port 17
eio 17 0

# start data process. This will power up port 17
aup

# wait a bit, then
ds
ctrl-C


# If the 7500 doesn't respond, try power cycling it:
eio 17 0
eio 17 1

On site: Golubieski, Semmer, Militzer, Maclean. Dave Gochis was
also at the tower site, installing soil sensors.

Installed splint at ding in tower upright.

Reinstalled TRH transducers in ventilation units at all levels.

Started installing Licor 7500's. At 43 meters, S/N 1167, port ttyS17.

Measured total power draw at data system, prior to and after unit 1167
was installed:

Measured power draw of the 43 meter 7500 only, with serial line power meter at
the adam:

Tried to prepare units 813 and 1163 for installation at 30 meters, but could not get them to boot and run with required length of cable. Red LED at circuit board would stay on, or blink on and off. It is supposed to go off once the unit is running. Measured 8 V at the end of 30 meter cable with unit attached.

Installed S/N 1163, and 1164 at 30 and 16 meters, but witout data/power cables.

DC power supply in the enclosure that is charging the batteries is rated at 3 A, which will not be large enough to drive system with 5 Licor 7500s, since each Licor needs about 0.9 A.

The beacon was running off a separately charged battery with an inverter. Connected the beacon directly to AC power and added the battery to the bank of 2 that power the data system and tower sensors. So the beacon is not a load on the DC supply anymore, and there are 3 batteries providing power to the tower, that are charged by the DC supply via a charge controller.

Installed Kipp and Zonen CNR1 net radiometer. Data is being received. Distance from top of CNR1 boom to top of tower base plate is 22.38 meters. Chris said that per the bubble level indicator the unit is quite level.

Distance from top of CNR1 boom to top of 16 meter sonic is 6.31 meters. So the top of this sonic boom is at 22.38-6.31 = 16.03 meters.

Moved network switch from adam to power enclosure. Dave Gochis will probably use one of the ethernet ports for his Tsoil CR1000. After this switch, the fiber/copper media converter would not connect - even after several power cycles of converter and switch. Had to power cycle the media converter in the seatainer. This may mean that the fiber network will not always come up after a power outage without intervention.

Untaped pressure inlet (13:33 MST).

Updated NIDAS software on adam to version 5051M.

Installed anti-climb cage on tower.