Sanitary RTD Pt100 Probe with IO-Link, 4-20mA and Switched Output

In the field of industrial automation and manufacturing processes, quality and reliable communication between sensors and actuators are key components. IO-Link is a technology that brings a revolution in this domain. In this technical article, we will take a closer look at IO-Link, its advantages, functions and use in an industrial environment.

IO-Link is the world's first globally standardized serial communication protocol that is manufacturer-independent and enables bidirectional communication between a control system and industrial devices...

RTDs or Resistance Temperature Detectors, are temperature sensors that contain a resistor that changes resistance value as its temperature changes. The most popular RTD is the Pt100. They have been used for many years to measure temperature in laboratory and industrial processes, and have developed a reputation for accuracy, repeatability, and stability.

Most RTD elements consist of a length of fine coiled wire wrapped around a ceramic or glass core. The element is usually quite fragile, so it is often placed inside a sheathed probe to protect it...

The same year (1821) that Thomas Seebeck made his discovery about thermoelectricity (Seebeck effect, see thermocouples), Sir Humphrey Davy announced that the resistivity of metals showed a marked temperature dependence. Fifty years later, Sir William Siemens proffered the use of platinum as the element in a resistance thermometer. His choice proved most propitious, as platinum is used to this day as the primary element in all high-accuracy resistance thermometers, Pt100, Pt1000 etc.

In fact, the Platinum Resistance Temperature Detector, or RTD Pt100, is used today as an interpolation standard from the oxygen point (-182.96°C) to the antimony point (630.74°C)...

It is not practical to compare RTDs (Pt100 and others) and thermocouples generally. However, if we compare their performance in terms of specific criteria, we can see which is best suited for specific applications. Thermocouples are best for working at high temperatures. New manufacturing techniques have improved the measurement range of RTD probes, but more than 90% of RTDs are designed for temperatures below 400°C.

In contrast, some thermocouples can be used at up to 2500°C. Thermocouples are generally cheaper than RTDs...