2 datalogger programming, Datalogger programming, 1. rain – Campbell Scientific TE525, TE525WS, and TE525MM Texas Electronics Rain Gages User Manual

Page 16: Gage, Schematic, 3. multipliers for rain measurement

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TE525 Tipping Bucket Rain Gage

The CR10 does not support the use of control port inputs with the Pulse Count
instruction.

Black

White

Clear

100

Ω

FIGURE 7-1. Rain Gage Schematic

In a long cable, there is appreciable capacitance between the lines. A built up
charge could cause arcing when the switch closes, shortening switch life. A
100

Ω resistor is connected in series at the switch to prevent arcing by limiting

the current (FIGURE 7-1). This resistor is installed on all rain gages currently
sold by Campbell Scientific.

7.2 Datalogger Programming

This section is for users who write their own programs. A datalogger program
to measure this sensor can be generated using Short Cut. You do not need to
read this section to use Short Cut.

In CRBasic, the rain gage is measured using the PulseCount() instruction.
Choose switch closure (code 2) for the PConfig parameter. Dataloggers that
use CRBasic are the CR200(X), CR800, CR850, CR1000, CR3000, CR5000,
and CR9000(X).

In Edlog, the Pulse (P3) is used to measure the rain gage. Choose switch
closure (code 2) for parameter three. Dataloggers that use Edlog are the
CR500, CR510, CR10(X), CR23X, CR7, and 21X.

The multiplier used in the PulseCount() or Pulse (P3) instruction determines
the units in which rainfall is reported (see TABLE 7-3).

TABLE 7-3. Multipliers for Rain Measurement

Rain Gage

inches

millimeters

TE525

0.01 0.254

TE525WS

0.01 0.254

TE525MM

0.00394 0.1

TE525 or TE525MM w/8 in funnel 0.0057 0.1459

The volume of water required to cause a tip in the TE525 and the TE525MM is
the same. The difference in calibration is strictly due to funnel size. If the
CS705 Snowfall Adapter or other eight inch funnel is installed on these gages,
use a multiplier from the last row in TABLE 7-3. (The CS705 will not install
directly on the TE525MM; the MM funnel must first be replaced with an eight
inch funnel.)

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