NOVUS AUTOMATION
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FIELDLOGGER OPERATION
ANALOG INPUTS
FieldLogger
has eight channels for reading analog variables. The types of accepted signals and sensors are the
following: thermocouples J, K, T, E, N, R, S and B; RTDs Pt100 and Pt1000; 0 to 50 mV; 0 to 60 mV; 0 to 20 mV; -20 to
20 mV; 0 to 5 V; 0 to 10 V; 4 to 20 mA and 0 to 20 mA.
The accuracy of these types of signals is described in the
Specifications
section. The connection of these signals is
described in the
Connections and Installation
section.
In these inputs, we use an analog/digital converter (A/D) with high resolution (24 bits) and accuracy. In the desired scan
interval, all the analog channels enabled will be read. The ratio between the number of channels enabled and the scan
time is limited up to 1000 readings per second. In other words, we can have one channel being read 1000 times per
second, two channels being read 500 times per second and so on. So, the A/D converter will work faster in order to cope
with the desired channels scan.
The A/D converter has the property of having a better signal-noise ratio when operating at low speeds (larger scan
intervals), as well as better immunity to noise from the power grid and a higher effective resolution. In such way, in order
to obtain better results in the analog inputs reading, it is strongly recommended to use the largest possible scan interval
for the application. In the same thought, it is recommended to disable all the channels that are not necessary, because
the increase in the number of enabled channels causes the A/D converter to work faster in order to cope with the scan
rate configured by the user.
Each type of input signal has a valid range of measurement (detailed in the
Specifications
section of this manual).
However, the equipment usually can measure signals that exceed the limits of this range. How far beyond the valid range
will depend on the type of the configured input and may vary from device to device.
The following table outlines what to expect in the indication of
FieldLogger
depending on the signal applied at the input,
for each type of configured input.
INPUT TYPE
CONDITION OF INPUT SIGNAL
INDICATION
Thermocouples:
J, K, T, E, N, R, S and
B
Within the range
Value read from input
Open thermocouple
Value of configured error
Just above the upper limit
Value read from input *
A little below the lower limit
Value read from input *
Far above the upper limit
Value of configured error
Well below the lower limit
Value of configured error
Pt100 and Pt1000
Within the range
Value read from input
Pt100/Pt1000 with one or more wires
disconnected
Value of configured error
Just above the upper limit
Value read from input *
A little below the lower limit
Value read from input *
Far above the upper limit
Value of configured error
Well below the lower limit
Value of configured error
Voltage (mV):
0 to 50 mV,
0 to 60 mV,
0 to 20 mV
and -20 to 20 mV
Within the range
Value read from input
Disconnected signal
Value of configured error
Just above the upper limit
Value read from input *
A little below the lower limit
Value read from input *
Far above the upper limit
Value of configured error
Well below the lower limit
Value of configured error
Voltage (V):
0 to 5 V
and 0 to 10 V
Within the range
Value read from input
Disconnected signal
Value close to 1.8 V
Just above the upper limit
Value read from input *
A little below the lower limit
Value read from input *
Far above the upper limit
Value of configured error
Well below the lower limit
Value of configured error
