Below is a more detailed description of the application types described in the previous section.

The figure below shows a typical situation for the first application type.

The adapter is connected to the 4 ... 20 mA loop, which is used to transmit the measured value to the control system, or transmit the control value to the actuator. This does not affect the control system.

The data, especially the diagnostics data, from the devices is transmitted over the connected adapter and the wireless HART network to the IE/WSN-PA LINK. The link makes this data available over Industrial Ethernet to a diagnostics and maintenance station with installed SIMATIC PDM software. To eliminate the installation costs for the Ethernet cabling, you can use Industrial Wireless LAN. An extensive product spectrum of Scalance W components is available for this purpose.

The existing control system is not affected by the WirelessHART adapter.

The figure below shows a typical situation for the second application type.

WirelessHART is an evolutionary subsequent development of the HART standard

The integration of WirelessHART in SIMATIC systems takes place parallel to the integration of wired devices with HART or PROFIBUS interfaces. The 4 ... 20 mA cable to the control system is omitted in this case: All data, which means process data, parameters, diagnostic information and functions, is made available to the automation system wirelessly. This is mainly important during reconstruction measures and expansion of existing plants and, of course, in new plants, but also for temporary and mobile measurements.

The field devices are standard devices with connected adapters or those with integrated wireless capability.

We basically have to distinguish between wireless communication and power supply of the devices.

When installing a field device, the planning and installation of the data cable to the control system is usually considered a significant cost driver. The costs are significantly reduced through the use of wireless communication.

When using 4-20 mA/HART field devices with adapters, the question of power supply always arises - in contrast to battery-powered field devices with integrated wireless modules. It is important to distinguish between two- and four-wire devices here. Under certain circumstances, the SITRANS AW200 adapter can take over the supply of a connected two-wire device. The power consumption of the field device plays an important role here. If it is too high, an additional power supply becomes necessary. If more than one device is connected to the SITRANS AW200 adapter, an additional power supply is generally required. Four-wire devices always require an additional power supply.