ADS Environmental Services Model 4000 530017 A0 - Manual (Page 17)

System Overview 2-5
Maintaining the monitor time and date
Performing power management
Providing each board with the parameters required to carry out
the associated operations
Outputting a discrete signal to a sampler
Transmitting the stored and current data to the user's PC
The board allocates portions of memory to firmware (permanently
stored software), data storage, and program manipulation and
calculation. A light-emitting diode (LED) located on the processor
board indicates monitor communication status. The LED
illuminates when the processor board is involved in external
communications. A second LED indicates the processor board's
current level of activity. The light increases in brightness as
processor board activity increases. The board also includes the
monitor clock and a 3-volt lithium backup battery. This battery
maintains the monitor memory during a battery pack swap or power
failure. Battery backed RAM chips provide backup power to the
memory if the 3-volt lithium battery fails.
Sensor Interface Boards
The 4000 flow monitor chassis supports two sensor interface
subsystems:
A velocity subsystem consisting of two boards supporting the
Doppler velocity sensor
A depth subsystem consisting of one board supporting both the
pressure depth sensor and the ultrasonic depth sensor
The sensor interface subsystems communicate with the
corresponding sensors to acquire data, take sensor readings, and
convert raw data to the appropriate engineering units of
measurement.