CS115 Barometric Pressure Sensor

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".

5