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CS115 Barometric Pressure Sensor
5
4. Wiring
The CS115 wiring instructions for the example programs are shown in
Table 4-1. For dataloggers CR500, CR510, CR10(X), CR23X, and CR5000,
analog channel is used for period averaging measurement. For CR7, 21X and
CR9000 pulse channel is used for pulse count measurement.
TABLE 4-1. Wiring for Example Programs
Wire Color Description CR10(X) CR23X 21X CR5000
Green Frequency Out SE6 SE24 P1 SE33
Red Supply (12Vdc) 12V 12V 12V 12V
Black Power Ground G G G
Yellow Signal Ground AG
Blue External Trigger C8 C1 C6 C1
Clear Shield G G G
5. Programming
There are two ways to measure the output of the CS115. The preferred way is
to use the period averaging instruction available with the CR500, CR510,
CR10(X), CR23X and CR5000 dataloggers. This instruction determines the
period of the output signal averaged over a user-specified number of cycles and
outputs it in kHz.
If you have a datalogger that does not support the period averaging instruction
(e.g., 21X, CR7 or CR9000), a pulse count instruction can be used to measure
the CS115.
Atmospheric pressure changes little with time. In most weather station
applications measuring pressure once an hour is adequate.
In Example 1, the datalogger turns on the CS115 one minute before the top of
the hour with a control port. As in the example, the execution interval must be
one minute or less. The datalogger measures the CS115 on the hour, and then it
turns the CS115 off.
In Example 2, the CS115 is measured every execution interval. The datalogger
turns the CS115 on and waits two seconds for it to warm up before the
measurement is made. The execution interval must be long enough to
accommodate the two-second warm-up delay plus all the other measurements
and processing instructions in the program.
Example 3 resembles Example 1 in every way, but it is for the CR23X.
In Example 4, the CR5000 measures the CS115 once an hour in a program that
runs at 10 Hz. With the CR5000, the period averaging instruction has to be
executed every scan and cannot be inside the “If” statement. The measured
value, therefore, is first written into a temporary variable called "CS115_Freq".