Maybe it is a trend server as well as an alarm server. It can also be a combination of these, say an alarm server which is also used as a display. an alarm or trend server which has a constant demand for certain data points. It can be a plain display client, which only requires data for displaying graphic pages, or occasionally alarm or trend pages. The Client Typically a client of data is one of a number of types. Consider a whole system, from client to PLC. It depends on how you are making use of the data the system can provide. So how fast will my Citect run? How much load will it introduce on to the supporting hardware? Well. As it happens, some alarm information is pushed out to clients from the server but this is the only instance of this kind of data transaction. These machines have a relatively constant requirement so that they can continue with their respective tasks. An alarm server or trend server is also a user of Citect data. It requests only this data of the associated I/O server(s) which endeavours to produce it.
A client displaying a graphic will require the data needed to animate the page at a rate defined by the scan time. By this I mean that the users of data in a Citect system determine how fast data should be delivered and the nature of that data. Citect as a system is almost entirely client driven.
To clear up these scope related questions, this article will be confined to speed related issues. Some might consider reliability as the ultimate performance indicator. To others the term performance may refer to how many trends Citect can sample at a certain speed or how many alarms Citect can process. Some people consider good performance to be how fast Citect displays PLC data on a graphic screen. Citect performance means different things to different people. LEGACY TECH NOTE # 2326 SITUATION CitectSCADA 3.xx, 4.xx, 5.xx ACTION This is an attempt to compile a comprehensive list of information about getting the best possible data transfer performance out of your Citect system.
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