YSI Vertical Profiler Systems - Manual (Page 27)

YSI Profiler System USER Manual
powered to travel the required distance. It then powers the motor for the calculated time and
checks again to see if the sonde depth is within the +/- 0.2 meter tolerance. If not, the motor is
powered again until the sonde reaches the specified depth. The rate of movement is 0.1
meter/second, so a “step” may take a couple of minutes to reach its target.
Figure 2-5 Block Diagram: Sonde Control with Depth Sounder
When the sonde reports it is within the START depth position of one (1) meter +/- the tolerance,
it stops to stabilize for 60 seconds and then warms up for the specified DO warm-up time.
Depending on the sonde default DO warm-up time values are set at 40 or 60 seconds. After
about 100-120 seconds have expired, the CR10X sends an SDI-12 command directly to the
sonde to start parameter measurement. When completed, the CR10X stores the sample data in a
designated memory location. Therefore, all data in this memory array are SDI-12 measurements
taken directly from the sonde to the CR10X data logger memory. This array 105 includes the
Julian day, time stamp and sonde data. The time stamp indicates the end (not the beginning) of
the sample collection.
Once the data is stored in CR10X memory, a command turns the motor on for a calculated
period of time. This duration is the time it takes to move the sonde to the next step location (+/-
the specified tolerance). The sequence described above repeats until the END step is completed.
While profiling up or down the program keeps track of the sonde depth. When it reaches
approximately 80% of the overall water depth, the system checks the depth sounder again and
determines the distance to the bottom. From this point on the program continually checks depth
to insure it can do a full one meter step. Eventually, the step size of one meter is no longer
possible without hitting the bottom. At this point a calculation by the program determines a
partial step (typically 0.3 to 0.8 meters). When this step is completed, the CR10X issues the
command for the sonde to return to PARK position, where it waits for the next profile time.
Since this example location has a tidal influence, the overall depth will change from profile to
profile. The distance and/or steps may be more or less than a previous profile. Because this
sequence started at the surface, all of the steps are referenced from the surface down. The
opposite would be the case when starting at the bottom for a ‘bottom to top’ profile.
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669523 Rev B Page 2-18