ISA100.11a Technology Standard

ISA100.11a is an open-standard wireless networking technology developed by the ISA100 Committee of the ISA. The standard was the first robust standard in the industrial automation marketplace. The ISA100 committee was formed in 2005 to establish standards that will define procedures for implementing wireless systems in the automation and control environment, with a primary focus on the field level. The committee is made up of more than 400 automation professionals, representing end users, wireless suppliers, DCS suppliers, instrument suppliers, PLC suppliers, technology suppliers, system integrators, research firms, consultants, government agencies, and consortiums.

In 2009, the ISA Automation Standards Compliance Institute established the ISA100 Wireless Compliance Institute also known as the WCI. The ISA100 Wireless Compliance Institute owns the 'ISA100 COMPLIANT' certification scheme and provides independent testing of ISA100 based products to ensure that they conform to the ISA100 standard. For more information on the ISA100 Wireless Compliance Institute, please visit www.isa100wci.org.

In May 2009, the ISA100 standards committee voted to approve ISA100.11a, and in September of 2009, the ISA officially released the ISA100.11a standard.

Architecture

The Nivis ISA100.11a System is composed of the following functional entities:

  • Field device—Routing
  • Field device—Non-Routing
  • Backbone Router
  • Gateway
  • System Manager
  • Security Manager

The architecture of an ISA100.11a system is flexible, allowing various network topologies to be formed by combining the various functional entities listed above, based upon the application requirements. The Nivis ISA100.11a System incorporates firmware, hardware and software for all its functional entities, thus providing a comprehensive solution.

Field devices form wireless packets coined as DLL subnets. Depending on the application and the available network backbone infrastructure, there are two major network topologies: ISA100.11a network with no backbone and ISA100.11a network with backbone.

ISA100.11a Network with No Backbone

This topology addresses customer needs for smaller deployments. It concentrates all wireless field devices into a single DLL subnet that communicates directly with the gateway and the System/Security Manager without relaying the packets over an infrastructure backbone. This topology allows for reduced communication latencies as well as better predictability of network behavior.

ISA100.11a Network with Backbone

When deployments stretch over a larger geographical area such as interconnected halls within a plant, the favored topology is an ISA100.11a network that connects multiple DLL subnets through a network backbone. This topology facilitates extension of the ISA100.11a network, both geographically as well as in terms of number of devices.

The DLL subnet ends at the Backbone Router, which provides a communication link between the wireless field devices and the backbone infrastructure. The technology employed in the backbone is not mandated by the ISA100.11a workgroup. Both wireless and wired backbones are viable options.