Looking at the large number of possible applications and configurations, we generally differentiate between two application types.

Background for the first type is the fact that according to estimates forwarded by the HART Communication Foundation (HCF), approximately 85% of the over 30 million HART devices in operation are used in an environment where only the 4 ... 20 mA interface rather than the HART interface of the device is used on a system level. Generally, data on the device can only be read on site. This is of particular disadvantage with devices that contain self-diagnostic functions - that’s what we call "stranded diagnosis".

In these cases, a WirelessHART adapter can offer assistance. Connected to the 4 ... 20 mA loop, it allows central access to the device based on wireless communication. It does not affect process control systems which continue to receive the measured value using the 4 ... 20 mA loop.

Central access is enabled through a diagnostic station with SIMATIC PDM and SITRANS MDS software.

Main advantages:

• Increases the availability of the plant
• Increases plant transparency
• Reduces costs due to employing a predictive rather than preventative maintenance concept
• Reduces travel time in larger systems based on central access to field instrumentation

In the second application the 4 ... 20 mA loop is omitted, all data including measured process values and diagnostic information are transmitted wirelessly to a process control system, for example.

Main advantages are:

• No planning and installation of data cables, resulting in significant cost reductions
• Higher system transparency due to additional and hitherto unfeasible installation of measuring points
• Process optimization due to flexible, temporary and cost-effective measuring points via wireless communication
• Utilization of proven devices by using adapters
• The WirelessHART meshed network also makes it possible to bridge longer distances