MESH - WiFi Integration




In any type of wireless sensor network the information gathered by the field devices must be available to personnel so that they can examine and interact with the supplied data. This human interaction with the data can be accomplished in several ways.


The traditional approach to control system data interaction is via the centralized control room reminiscent of the IBM centralized main frame computer where all the data was stored, analyzed and manipulated. The development of the Internet has changed this classical topology to emphasize decentralized storage and control using high speed communication systems to store and examine the data.


The WiWIZ1 provides the user with a decentralized Internet based approach based on high speed Ethernet and WiFi (IEEE 802.11). The network regardless of the wireless protocol used on the device sensor network can store all the information on a small embedded server at the source of the data.


How does decentralized storage work?


Mesh Networks


The wireless sensor device (WiWIZ1 and tiny uSM modules) gathers and stores the data for transmission. They have very powerful low power microprocessors which can preprocess data if required. There is a free software development system to write customer and application specific software to provide unique and specific analysis of the captured data.  This is available on the WiWIZ1.  The WiWIZ1 is a dual processor device.  The RF module executes the wireless protocol and the application processor does the data acquisition and preprocessing.  Since all WiHART systems using the WiWIZ1 have  the same microprocessor and development environment, application  software can be transferred to another RF protocol with a minimum of effort.


Let us assume we are using a wireless mesh based on IEEE 802.15.4. The information is gathered by the individual sensor nodes and is eventually passed to the gateway. The gateway hardware can be the WiWIZ1 which contains a small device that is both an Ethernet port with an RJ-45 connector and a webserver . In addition to Ethernet port there is a 32-bit microprocessor which maintains a complete Internet webserver. The information from the wireless mesh arrives at the gateway and is passed on the serial port to the Ethernet webserver. This webserver can be accessed by any device with a standard browser either on an local Intranet or on the Internet. The webserver uses the maximum standard Internet security protocols presently available.

The Wi-WIZ1 with the Ethernet webserver can be placed anywhere there is an Ethernet cable. The device uses Power Over Ethernet(POE). The is standard (802.11af) which describes the technique to put power on unused Ethernet wires for powering remote devices. One can purchase Ethernet switches and POE injector devices to power the Ethernet device and webserver.

IEEE 802.15.4 Wireless mesh and WiFi


The WiWiz1 is normally configured with one type of IEEE 802.15.4 (It could be wireless HART, ISA100 or Zigbee). The data is gathered and examined locally using the low power 15.4 mesh, but instead of being transferred back to WiWIZ1 15.4 gateway, a small low power WiFi module is added to the remote sensor device. It now has two(2) radios (they do not operate simultaneously). The 15.4 mesh does the data acquisition and WiFi provides the backbone connection.


The information is passed to the WiFi modules which maintains a link with a local access point. The small WiFi module on the sensor device is ultra low power as compared to standard WiFi transmission i.e. laptop computers and PDAs.


Wireless mesh with WiFi


Normally WiFi is run in a master-slave mode with an access point acting as a master in a star configuration with all nodes talking to the closest access point. WiFi may also be configured in a wireless mesh and can communicate with an access point capable of mesh capabilities.


The Wi-HART Systems industrial access point is capable of being configured in both the standard master/slave access point and as a wireless mesh node capable of transferring data to the Internet. The Wi-HART systems access point also has a second WiFi radio which can act as a backbone network on the 5 Gigahertz band which has less interference due to the lack of other devices operating on the band.

Industrial WiFi Access Point

Wireless Micro Sensor Interface Modules (uSIM) with WiFi


WiHART Systems has released the first of a series of miniature wireless sensor modules beginning with the WiVIB1. This complete wireless sensor node measuring about 1 square inch will be available with a WiFi radio. The vibration information can be transferred directly to a standard access point or the WiHART Systems industrial dual radio access point.


If you examine Figures 1&2 below you will see the hybrid architecture of the mesh and WiFi.



Figure 1






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