Example 4-20mA thermistor transmitter wiring diagram
The 4-20mA transmitter can
be looked at as a temperature controlled variable load, in series with the
power supply and current measurement shunt resistance. The effect is similar
to the transmitter acting like a potentiometer, that will vary total load resistance
(according to change in temperature), varying total current in circuit; to
be measured as a voltage change across the current shunt resistance.
When the ROI-XMA Thermistor
transmitter is wired, with the correct DC power supply and current measurement
device, the transmitter is wired as a 4-20mA loop circuit; as shown in the
following diagram.
When the ROI-XMA Thermistor
transmitter is used with the ROI-USB current measurement A-D, the PC can be
used to measure a Thermistor with higher precision than a direct measurement
system.
The 4-20mA transmitter gain can
be adjusted to minimize the span of the temperature sensor range. The result is a
PC temperature recorder, with precision greater than a tenth of a
degree.
Multiple transmitters can be connected to the
same A-D, to form a multi channel Thermistor data acquisition system.
In addition to the ROI-USB A-D, the ROI-XMA
Thermistor transmitters, and Thermistors; a PC and software are also
required, to form a complete Thermistor data acquisition system.
When the ROI-USB is used with
Excel; tremendous flexibility is added to the system. Excel can be used to
provide real time display and analysis of the data. As simple a system as,
values of temperature displayed in a chart;
with updated data values linked to ROI-USB.
Learn more about the ROI-XMA
Learn more about the ROI-USB
