Resistance Divider Configuration
Rs/Rf Option
Vs/VExc Option
View the analog inputs arrangement
Up on the left in the configuration window, you can see the box for the type of measurement selection. Select:
• Rs/Rf to configure an input for 2-wire resistance measurements. Using
this option the datalogger measures the value of the Rs resistance offered by
the sensor compared to the value of the Rf reference resistance.
• Vs/VExc to configure an input for 3-wire potentiometric measurements.
Using this option the datalogger measures the value of the Vs voltage at the
input compared to the value of the VExc excitation voltage.
Name
Identification name of the sensor. You can assign the name, for example, of the sensor model, or the type of measured parameter. The name should begin with a letter and can be maximum 12 characters long. The name unequivocally identifies the measurement being input; you cannot assign the same name to multiple measurements.
Unit
Unit of measurement of the quantity detected by the sensor. It should begin with a letter and can be maximum 12 characters long. The unit of measurement should be in agreement with the values of the Offset and Gain parameters.
Channel UNI
It indicates the number of the analog input to which the sensor should be connected.
The software automatically assigns the first input free. The number cannot be
changed by the user. The programmable inputs for this type of measurement are
only the single-ended inputs 1, 2, 3 and 4.
Channel Exc (Excitation terminal)
It indicates the number of the terminal E from which the excitation voltage is taken, that is, the terminal on which to connect one side of the reference resistor Rf. The number is assigned automatically and cannot be changed by the user.
VExc (Excitation voltage)
The excitation voltage applied to terminal E. The fixed value is 2500mV.
Rs/Rf Range
This field appears only if the Rs/Rf option is selected, and indicates the Rs resistance measurement range of the sensor compared to the value of the Rf reference resistance. The field cannot be set. The Rs measurable range depends only on the value of the Rf reference resistance. The minimum and maximum measurable values are, respectively: Rsmin = Rf / 1000, Rsmax = 100 x Rf.
Offset and Gain
The value recorded in the datalogger is the result of a linear formula applied to the measured value. If you select the Rs/Rf type of measurement, the formula is:
Value recorded = Offset + (Gain x Rs/Rf)
If you select the Vs/VExc type of measurement, the formula is:
Value recorded = Offset + (Gain x Vs/VExc)
The input of proper Offset and Gain values, allows converting the measured input value into the value of the corresponding physical quantity, and to directly record the physical quantity value in the datalogger (please see the datalogger operating manual for the Offset and Gain values calculation modes according to the sensors' measurement ranges). You should only enter the numeric value, without unit of measurement, in the Offset and Gain fields. The unit of measurement should be entered in the Unit field.
Error messages
If the configuration parameters are not correctly input, you can get the following error messages.
The name and Unit fields are required !
Cause: the identification name or the unit of measurement fields were not filled.
There is just an equivalent Name !
Cause: you previously entered a sensor with the same name. You should change the identification name.
Gain must be not zero !
Cause: the Gain field has not been filled or zero has been entered.