As a provider of humidity measurement technology, Testo has made a common field bus available: Profibus-DP. This has become standard in production automation and is also used for drying processes.
While humidity measuring systems in particular are sparking off a price war in air conditioning technology and requirements such as precision and system availability become of secondary importance, precision and reliability are key requirements in industrial humidity measuring technology for all those responsible for plants.
This applies equally to clean room applications and industrial drying processes.
Many of these applications, such as those in the food or pharmaceuticals industry, are embedded in an environment of factory automation in which readings are transmitted not only by means of analogue signals but increasingly via field buses.
Compared to alternative field buses, the humidity transmitter has established itself good. More than 20 million Profibus nodes (measuring points) have now been installed worldwide, and the voices which dismissed this humidity transmitter as merely the proprietary bus of all Siemens control systems have long been silenced.
In view of this, it is somewhat difficult to understand how or why humidity measurement has so far failed to make use of the Profibus connection.
Even highly-specialised analytical measuring variables are now available as Profibus versions; variables such as temperature and pressure are offered by well over a dozen providers with a Profibus output.
The situation in humidity measurement was rather different: none of the providers in this field have yet made the transition from analogue output or from proprietary digital outputs to an interoperative field bus such as the Profibus.
Testo AG has now closed this gap. With the new testo 6681 humidity transmitter, which offers optimum precision and calibration for every application due to digital probes, a humidity transmitter with a Profibus interface has been released.
Ideal for the user: The connection of the Profibus is designed as an intermediate layer, i.e. a sandwich design means that the Profibus interface can either be ordered ex works or be retrofitted on site at a later date. This retrofitting requires neither specialist knowledge nor special tools and can therefore easily be carried out by the customer.