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21 March 2018

What is a transmitter?

Transmitter literally means “transducer”. They are devices that detect value changes in processes in various structures.

Transmitters are a kind of signal converter. It is the intermediate device equipment that measures the environmental variables such as flow, temperature, level, humidity, ph detected by the sensors and converts them into low-current electrical signals that control devices can understand. These electrical signals can be in the range of 0-10 V or 4-20 mA, which is commonly preferred depending on the user’s request. These control devices can be devices such as display, PLC, HMI, signal converter. Thanks to this basic structure, they can make the process they are in work.

Transmitter Measurement Calculation
For example, when a temperature transmitter is taken into account, PT100, Thermocouple and a different type of sensor detects a temperature ranging from 0-100 °C. As the temperature value in the environment changes, the data measured by the sensor will also change. The transmitter converts these variable values ​​from the sensor within the framework of certain standards and gives them to the user.

The formulation of this conversion is carried out as follows;

In the example, we will convert the value from the temperature transmitter to a 4-20 mA signal.

Linear mA output = 4 + (16 x ((Read Value – Low Limit) / (High Limit – Low Limit)))

Low Limit: The lowest temperature to be measured by the temperature transmitter is entered. For example, zero is a typical value for most temperature transmitters, but you can also add negative (-) or positive (+) values.

High limit: Enter the maximum value that the temperature transmitter will measure.

According to our example, if we measure the range of 0-100 C degrees; the low limit is 0 °C and the high limit is 100 °C. Let’s look at the current coming for a temperature of 50 °C;

Linear mA output = 4 + ( 16 x ((50-0) / ( 100-0)))

= 12 mA.

When 12 mA value is seen on the meter or controller, we understand that the sensor measures 50 °C temperature.

Another benefit of converting the signal into current is that the measured value can be transported over long distances without any loss through cables. In some processes, the process control panel (HMI, PLC, etc.) where dozens of measuring instruments are controlled with a sensor, that is, a measuring instrument, may be at a remote point of the field. That’s why transmitters have the advantage of converting and transmitting the measured value into current.

You can visit our product page to examine our wide range of transmitters to measure values ​​such as temperature, pressure, flow, level, humidity, ph.

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