- Posted by fedco
- On January 4, 2015
- 0 Comments
- wireless hart
The WirelessHART standard is the first open wireless communication standard for measurement and control in the process industries. It uses wireless mesh networking between field devices, as well as other innovations, to provide secure, reliable digital communications that can meet the stringent requirements of industrial applications. This is one of a series of papers helping users recognize the benefits of WirelessHART, as well as addressing specific questions about WirelessHART.
Peer-to-Peer Communication with WirelessHART
WirelessHART has been designed from the ground up to support a wide range of applications. These applications include monitoring, diagnostics, alarm and event detection, block transfer to support applications such a vibration monitoring and valve signature, and control. To support these applications several forms of communications are required. Although these forms of communications are largely transparent to the user, it is useful to understand that they exist.
This paper describes these communication patterns as forms of peer-to-peer communications. Peer-to-peer communication is defined as the transmission of information between participants in a network. Participants can be physical devices such as a transmitter and a valve, or they can be applications such as monitoring, control, diagnostics, and event detection. They can also be more complex applications performing calibration, a vibration analysis or a valve signature. These applications can reside in workstations, controllers, gateways, measuring devices, and final control elements such as valves.
This paper describes the various forms of peer-to-peer communication. A typical control application is used to illustrate these forms of communication. Communication patterns When a control algorithm runs in a dedicated controller such as a Distributed Control System or a PLC, the communication is between the controller and field devices. In other cases control may be distributed between controllers and a gateway-type device in a wireless network, or between controllers, gateways, and the field devices themselves. Running control in the field devices – often called “control in the field” – can be implemented in multiple ways. One way is to wire the 4-20mA signal from the measurement device directly to the controlling device, such as a valve. Another is to distribute and run software function blocks in the devices, and communicate process variables and control signals in digital form over the communications network.
In all of these scenarios parameter values are being communicated. These communications are built on top of a communication infrastructure. The role of the communication infrastructure is to transport process variables, parameters, alarms and other values wherever they are needed. The scenarios that follow illustrate how WirelessHART supports these many forms of communication.