B. Hargreaves, Sept. 2006
Greyline Instruments LIT25 (series 2.0) level indicator transmitter

In Early Sept 06 the sensor and datalogger were removed from the weir site after it was confirmed that there was a malfunction.  The immediate indication was the display on the sensor interface (displayed “CALU” instead of current water level).

The conduit was also removed (with difficulty) and will be reinstalled with nylon cable ties attached to the metal bar (badly rusted) at the top of the culvert.  To facilitate reinstallation a thin braided SS cable was threaded through the conduit as the sensor cable was pulled out.

The datalogger enclosure also needs major work as it is rusting and also by design will catch runoff and mud via the hinged lid.  I suggest a weatherproof plastic enclosure (this would require an electrician to reattach the AC outlet inside the new enclosure).  Even better would be a new datalogger that is compabible with a wireless spreadspectrum connection to a nearby building (ideally connected to a LAN jack but dialup access another option).  The power should be provided through a battery that powers the sensor as well as the datalogger, with AC power to trickle charge the battery.  If a 12V sensor cannot be used then an small inverter could power the AC line of the sensor while direct 12V can power the datalogger.  Campbell Scientific charger, datalogger, and wireless link could be used.

On 13Sept06 an RMA (RM 200648) was provided by Greyline for a no-cost assessment of the system.  It appears that the problem is within the interface because a signal can be detected from the sensor, but the interface does not work (keys, settings) via the interface.  Greyline also stated that they use a different interface circuit now.

They eventually reported that the sensor could not be repaired (the interface had probably been damaged by a voltage spike from lightning).  An alternate plan was developed to use an available self-contained submersible level logger (SOLINST brand) underwater behind the weir and barologger located in the steel box enclosure nearby to correct the underwater readings for changes in ambient pressure.