Introduction
Now it's possible to exploit WAP (Wireless Application Protocol) technology with the IGSS system to carry out surveillance and control duties via WAP enabled cellular telephones. The feature facilitates greater flexibility in planning duty personnel coverage because physical presence at the plant is no longer an absolute requirement in order to perform supervisory tasks.
With IWS installed, the WAP enabled cellular phone is able to communicate with the IGSS server in the plant. Information gathering to the cellular phone display as well as sending control commands to process components are performed by activating various keys on the phone. This is accomplished by using a CGI (Common Gateway Interface) script, which dynamically creates WML (Wireless Markup Language) pages. These are based on data collected at the IGSS server and made available through the IGSS Automation interface.
Main features in IWS
The IWS software offers three main features to WAP cellular phone users as described in the following.
Remote Alarm List
This feature provides a list of active alarms from the plant's IGSS system. Detailed information on object name, area location and alarm text can be obtained from the list. It is also possible to acknowledge an alarm.
Although the IWS service can be used alone on a WAP phone, the optimal solution would be to use IWS with the IGSS WinPager program. WinPager sends single SMS messages to the cellular phone for each alarm occurrence. Upon receiving the SMS alarm message, the user would then open the IWS Remote Alarm List for a detailed description and, if necessary, use the Remote Object Browsing feature to send a change to the object in question.
Remote Object Browsing
This feature allows the user to receive information on objects (pumps, valves, motors, etc.) in the configuration and to actively change their states, set points or alarm properties. For security purposes, permission to carry out these tasks are defined in the IGSS User Administration module.
Due to present limitations in size of cellular phone displays, limiting the number of objects available for IWS supervision when setting up the IGSS configuration is recommended.
Remote Report Editor
This feature allows for manually keying in data from process components not connected to the IGSS surveillance system. For this purpose, Remote Report Editor uses the same type of report scheme and format as the standard IGSS module called the Manual Report Editor (MRE). The use of this feature is ideally suited for reading and manual recording of data by personnel on visual inspection rounds of the plant.
System requirements
IWS must be installed on a PC functioning simultaneously as an IGSS server and WWW server. Web server requirements are basically the same as for hosting a web site consisting of standard HTML pages. The Internet Information Server/Services (IIS) from Microsoft is one such Web server. Some additional settings and definitions are, however, required when configuring an IWS installation.
Communication requirements
Communication between the combined web and IGSS v3 server on the one hand and and the cellular phone on the other hand involves a third party gateway service typically provided by the telephone company to which one subscribes. The gateway acts as a translator between the two sets of protocols used, one for the cellular net and one for the Internet, and provides the Web server with information on the cellular phone being used. (See diagram above.)
As WAP technology is perfected, more detailed information on the type and functionality of the cellular phone employed will be available to the Web server. A case in point is that it is now possible to move the gateway directly on to the Web server. This greatly improves security in that access can now be controlled through, for instance, a modem instead of allowing broad access via the Internet.