Robert Owen Inc.
Sensor Measurement Solutions

Sensor Signal Conditioning,
Sensor Measurement Systems,
USB Sensor Measurement,
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A Simple 4-20mA Transmitter Operation Description.

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. 


Wiring diagram of a typical transmitter, power source, and measurement device; in a 4-20mA loop circuit schematic.

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. 

ROI-USB20 and ROI-2252XMA32115F used together allow high precision measurement of narrow temperature range.

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

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Read Blog Update 04/28/2017 Made In The USA        

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Phone 516-629-5134
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