webRC is currently developing a collection of common hardware and software tools which can be applied to support numerous wireless product applications, codenamed “WebSys”.  WebSys utilizes local low power wireless Zigbee technology for sensor interface and GSM/GPRS wireless for the interface to the internet. Customers can view data and modify control strategies anywhere in the world via secure access using a standard web browser. Click on “Demo” to see an example of the WebSys mySQL database application.

The System

The WebSYS framework consists of a webRTU access node, local wired/wireless WebRC Sensor Network and the Sensor_DB database application, hosted on Real-Time Control Technolgies’s secure server. The webRTU will collect data from the sensor network and can also interface with a PLC control panel, if required. Data from the webRTU will be sent via GPRS to the GPRS/GSM Interface Gateway. Using internet standard protocols, such as FTP, this encrypted data will be sent to the Real-Time internet server as a data file. The Sensor_DB database application will then use the data in the data file to update your specific products maintenance database and make it available to your maintenance personal for analysis.

The General Packet Radio Service (GPRS) network is an "always on", private network for data. It uses the existing GSM network to transmit and receive TCP/IP based data to and from GPRS mobile devices. Private IP addresses are typically dynamically assigned within the network to mobile devices. However, Access Point Names (APN's) provide a gateway route to other networks such as the Internet, WAP services or private corporate networks. Firewalls typically reside at the APN to isolate the public and private networks. IP addresses allocated to mobile GPRS devices are therefore not addressable from outside the GPRS network (e.g. from the Internet) without specialized services or infrastructure.

The Sensor Network

For local wireless interface, the WebRC Sensor Network uses the 802.15.4 (Zigbee) standard as a baseline and adds additional routing and networking functionality. The ZigBee protocol was developed by the Zigbee Alliance. The Zigbee Alliance is a group of companies that worked in cooperation to develop a network protocol that can be used in a variety of commercial and industrial low data rate applications. What ZigBee is designed to do is add mesh networking to the underlying 802.15.4 radio. Mesh networking is used in applications where the range between two points may be beyond the range of the two radios located at those points, but intermediate radios are in place that could forward on any messages to and from the desired radios. This mesh cabaility is ideal for a local area network utilized for sensor data gathering. It is a key technology that Real-Time Control Technologies utilzes when conventional wire harness technology is not possible.

Wireless Costs

Wireless costs have come down considerably over the past 2 years. The key to a low per point cost is optimization of connection, smart buffering data and low packet sizes. Real-Time Control Technologies has worked with our service provider partner to enable the lowest possible cost for data transfer. Total cost is application dependent, but per point costs are in the $8/month - $25/month range.