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ZENO

-3200 USER MANUAL

Coastal Environmental Systems (206) 682-6048

Page 171

The ZENO

-3200 sets the Excitation Voltage to the value specified in Line

Item #7 and turns on the Excitation Voltage Return Channel specified in

Line Item #8 only when a measurement from the sensor is being taken.

Sensor Warm-up Time DOES NOT APPLY to the Excitation Voltage. DO

NOT USE the Excitation Voltage IF your sensor requires a warm-up time.

The amount of available power that the Excitation Voltage provides is more limited than what the

Switched Voltage provides:

The Excitation Voltage can supply up to 100 mA.

You can put more than one sensor on a given Excitation Voltage Return

Channel, if the Excitation Voltage used by one sensor is not so large that it

will damage the others.

If you need to connect more than one sensor to a single Excitation Return

Channel, Coastal Environmental Systems recommends that the sensors

operate at the same voltage.

When the Excitation Voltage and the Excitation Voltage Return Channels are not in use, the connections

are floating. Thus, current will flow through your sensor only while the ZENO

-3200 is sampling the

sensor. This process avoids sensor self-heating problems and reduces the system’s power consumption.

With analog sensors, an important consideration with use of the Excitation Voltage and Return for

powering the sensor is the time required for the voltages to reach steady state: a measurement taken too

quickly after the Excitation Return is closed may result in inaccurate voltage readings. It may therefore

be necessary to set Line Item #17 in the analog sensor to a non-zero value to increase the delay time

between the time the Excitation Return is closed and the measurement is taken. Please refer to Section

10.3.1 for more information about setting Line Item #17.

10.3.13. Setting Scaling (Calibration) Coefficients

Scaling (calibration) coefficients are used primarily with analog and digital

sensors, and can be used to calibrate a sensor or to convert a voltage into

standard engineering units.

Line Items #13, #14 and #15 are used in each sensor record for the three scaling (calibration) coefficients.

They define the coefficients used in the following quadratic equation:

x = A v

+ Bv + C .

v is the unprocessed sensor output (in volts) represented by the A/D converter output, and x is the value in

the desired engineering units.

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Campbell SAT ARGOS Manual do Utilizador Página 179