September
2017
Sentinel V SC and RT Operation Manual
Page 24
EAR-Controlled Technology Subject to Restrictions Contained on the Cover Page.
Health & Environment Monitoring Sensors
The Health and Environment Monitoring (HEM) Sensors monitor the health of the Sentinel V Real-Time
system.
•
Operating Time
– The Sentinel V Real-Time system records the total time of operation in
minutes where “operation” is defined as the time that the system ping loop is active (CS com-
mand has been sent). The record of the total awake time has a maximum value of 33,554,432
minutes, which corresponds to over 500,000 hours of operation. The value of the counter can
be read as part of the PS5 command. Although the time is stored in minutes, the operating
time is reported in hours with one decimal place.
•
Pressure Cycles
– Sentinel V Real-Time systems with pressure sensors installed record the
number of pressure cycles (dives, casts, etc.) to which a unit is exposed during operation. A
pressure cycle is defined as “pressure is greater than 40% of maximum, followed by a pres-
sure that is less than 20% of maximum”. The pressure cycle counter has a maximum value of
16,384. Use the PS5 command to read the number of pressure cycles.
•
Maximum Pressure
– Sentinel V Real-Time systems with pressure sensors installed monitor
the pressure during operation and records the maximum pressure seen during the lifetime of
the instrument. This maximum pressure is stored in non-volatile memory. The PS5 output
will read N/A if no pressure was measured or recorded. Use the PS5 command to read the
maximum pressure seen.
•
Over Pressure
– Sentinel V Real-Time systems with pressure sensors installed monitor water
pressure during operation and record the number of events beyond the system’s maximum
rated pressure value. The system pressure rating is defined as the maximum pressure rating
of the installed pressure sensor. The system maintains a flag in non-volatile memory to indi-
cate whenever the pressure exceeds 100% of the maximum rated value, this flag is set to a ‘1’
value, and whenever pressure is less than 80% of the maximum rated value, this flag is
cleared to a ‘0’ and the over pressure cycle counter is incremented. Use the PS5 command to
read the number of over pressure events seen.
The Sentinel V Real-Time system pressure rating is defined as the maximum pressure rating
of the installed pressure sensor.
If an Over Pressure event occurs or the Maximum Pressure seen has exceeded the Sentinel V
Real-Time’s pressure sensor depth rating, TRDI advises returning the system to us for an
inspection before re-deploying.
Example PS5 output:
PS5
Operating time: 4327.5 hours
Maximum pressure seen: 652.378 dBar
Over-pressure events: 1
Pressure cycles: 25
