Sutron Corporation 8310 & 7310 Users Manual 8800-1125Rev. 2.7 (BETA) 4/16/2014 pg. 160
resistance to show significant changes in the resulting output voltage.
Pressure sensors or strain gauge sensors connect as a differential input using two analog
channels. These sensors are powered off VREF and GND and typically have an output of
between 5 and 50mV. The accuracy of these measurements is 0.0025mV.
Powered sensors normally have circuits that run off +5V or +12V and have an voltage or current
output. Examples of these sensors are some humidity, temperature, water quality, flow meters
and pressure sensors. These sensors will use the +12 from the 8310 (switched or directly from
the battery) or the +5 (switched or always on).
If the sensor has a current output, such as a 4 to 20 ma sensor, the output needs to pass
through a resistor so a voltage can be measured. An internal resistor is provide for making these
measurements on channels x and y. An important limitation of powered sensors is that the
ground line of the output needs to be common with the power ground.
Self powered sensors have a battery or require no power to operate. The most common
example of a self-powered sensor is a pyranometer. Self powered sensors can operate with the
8310 as long as the sensor ground can be connected to the 8310 ground. The pyranometer
would connect to any of the analog inputs of the 8310 and would use the 78mV input scale.
Digital Inputs
The 8310 counter circuits can be programmed to be either event counters totalizing the counts
that are received or frequency counters. In either case, the 8310 expects to see a 0 to 5 volt
signal from the sensor. Sensors compatible with the 8310 counter/frequency
Counter/Frequency Sensors
The 8310 counter circuits can be programmed to be either event counters totalizing the counts
that are received or frequency counters. In either case, the 8310 expects to see a 0 to 5 volt
signal from the sensor. Sensors compatible with the 8310 counter/frequency circuits are tipping
buckets, wind sensors with amplified speed output. Tipping buckets have a simple switch inside
that closes momentarily when the collector is emptied. This works with the 8310 because the
counter/frequency inputs have a pull-up resistor. When the switch closes the circuit is pulled to
ground which causes the swing from 5 volts to 0 and back to 5.
When used as counters, the circuits count up to 4294967295 and then roll over to 0. A clear
counter command will also cause the accumulator to reset to 0.
To Next Page
Loading...
