SCADA/HMI, a real time monitoring system is recently developed to be working on web. It is very common for people nowaday, to be able to monitor and control their home/office and plant remotely using a web client.
SCADA/HMI, which is characterized by rich mimic, has traditionally functioned as a desktop application. When SCADA/HMI is required to run on intranet or Internet, Java technologies and ActiveX technologies, which are not W3C standard, were mainly used to handle the extensive graphical animations over this media.
SVG has made rich animations possible over the net without using proprietary technologies. Ecava has developed and delivered its first SVG based SCADA system called “IntegraXor” as early as 2003. Ecava further developed XSAC (IntegraXor SCADA Animation Code) which allows animations to be done easily by linking a JavaScript animation library instead of doing JavaScript programming. XSAC is a series of animation attributes written in JSON format which can be easily generated. Ecava has developed SAGE (Scada Animation GUI Editor) based on Inkscape for such purpose.
The JSON syntax contains the animation to work, a tag name to be listen, and the parameters to take action. For example a circle created in Inkscape is given a COLOR animation, and the color of the object shall change according to a predefined parameter associated with the tag value, which update from server. The update procedure requires a Javascript library to loop and make HTTP request to server.
Major Animations for SCADA application are Color, Level, Movement, Opacity, Rotate and Text. They are all tied to at least one variable which is normally associated with data from an external field equipment. The animations shall correspond to the actual status of the field equipments. |