YSI WaterLog Series, Руководство пользователя

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Analog Input Section
The lower right terminal strip is used for analog input functions. This includes four analog
inputs, two analog grounds, and one +5Vref excitation connection.
Analog Input Channels
There are four analog input channels labeled Vin1 to Vin4. The standard input range for all
channels is 0 to 5 volts; however, because the Analog to Digital converter is highly accurate, it
can accurately measure low level ranges as well. Differential measurements can also be made on
channels Vin1 and Vin2 or on channels Vin3 and Vin4.
Analog Grounds
There are two analog ground connection points. In order to preserve signal integrity, it is
important to use the analog grounds only for sensors connected to the analog section. The current
flowing through an analog sensor is relatively small and normally very stable. If a digital sensor
has its ground connection tied into the analog ground, the currents from the digital sensor will
flow through the analog circuitry causing voltage level shifts and noise based on digital
switching. There should be sufficient digital ground connection points for the digital sensors.
Power grounds should not be connected to analog grounds.
Sw5.00 Volt Reference Excitation
The +5Vref output is used for analog sensors requiring a precision reference voltage. The
maximum output current is 10 milliamps. The Analog to Digital converter uses this excitation for
its reference to provide a ratio-metric relationship for sensors using this excitation.
System 5000
Hardware Overview 2-5
TM