Wireless ideas still stirring

The ISA-SP100 Wireless Systems for Automation committee plowed forward Tuesday at ISA’s headquarters in Research Triangle Park, N.C. It is addressing wireless manufacturing and control systems in the following areas:

-- Environment in which the wireless technology is deployed
-- Technology life cycle for wireless equipment and systems
-- Application of wireless technology

On Tuesay the committee was in its second day of hearing proposals to solve issues associated with the deployment of wireless technology for industrial automation. Presentations included:

Shenyang Institute of Automation’s proposal focused on the wireless networking of field devices. Shenyang is a major Chinese robot-technology research institution. Its proposal covered the DLL/Media Access Layer, Infrastructure Layer, and Device Management Layer that the SP100.11 and SP100.14 RFP define. The performance parameters considered were throughput, reliability, energy consumption, and latency. The organization’s proposal uses the communication services provided by the direct sequence IEEE 802.15.4 radio at 2.4 GHz, and provide end-to-end data transmission services and network management services to the applications of Classes 0-5.

Analog Devices’ proposed network topology emphasized the overall network consists of several co-existing sub-networks. In addition, each sub-network has a star configuration with a scalable number of base stations (BS) at the center talking to a number of endpoints (EPs). While the physical network configuration may be relatively ad-hoc, all nodes must be able to hear the BS but will not necessarily be able to hear one another. For installations where there are dead spots, a powered repeater can add in, resulting in one (and no more than one) extra ‘hop’ to the base station. There is peer-to-peer (EP - EP) communication that gets its support from network but not direct communication (REQ 3.3-12). Further, there is multi-hop routing (REQ 3.3-6) supported through means of main-powered repeater node. Finally, multiple SP100 networks will be able to co-exist in a shared air space by means of orthogonal network codes.

Texas Instruments intends to leverage available technology. The physical layer (PHY) is IEEE 802.15.4 2.4GHz. Media Access Control (MAC) is IEEE 802.15.4-2006 (also referred to as IEEE 802.15.4b) with simplifications, and the upper layers rest on Zigbee with feature adjustments.

Advance Industrial Network’s proposal for ISA-SP100.11 and ISA-SP100.14 emphasizes practical implementation of potential solutions based on modifications and additions to existing standards on the PHY and MAC layers. Its scheme pays special attention to the coexistence and interoperability of radio signals.

Within ISA-SP100, there is a group comprising the Wireless Network for Secure Industrial Applications (WNSIA). Yokogawa presented with reference to this group’s concerns. In the group are 3eTI, Adaptive Instruments, Endress+Hauser, Flowserve, Honeywell, Omnex Controls, and Yokogawa Electric Corporation. On Monday, Honeywell presented an overview of the group’s proposal. Yokogawa explained the features and advantages of the WNSIA-group proposal from an application point of view.
Sensicast’s proposed solution sits on IEEE 802.15.4, with extensions. It operates at its best between gateway and field devices. It aims to leverage an IP backbone when that backbone is available. It is a self-configuring network with no single point of failure. It embraces a hybrid of TDMA/CSMA.
In conjunction with and as extension to Sensicast’s proposal, STG (Software Technologies Group) laid out the top points of the two companies’ combined: a) Based on IEEE 802.15.4, with extensions; b) Optimized for communication between gateway and field devices; c) Seamlessly leverages IP backbone where available; d) Self-configuring network without a single point of failure; e) CSMA/TDMA hybrid, decentralized; and f) Security strategy for moving forward.