RSView Supervisory Edition Installation Guide

• • • • •RSVIEW SUPERVISORY EDITION USER’S GUIDERelative referencesRelative references point at a tag relative to the current server or area. For example, arelative reference to a tag called Extractor is simply the tag’s name: Extractor. When arelative reference is used, RSView assumes that the tag is located in the current area.Use relative references, for example, when you want to re-use tag names in an applicationfor a plant that has identical production lines. The application could have multiple areas,each representing one of the production lines, with the same tag names in each area. Formore information about areas, see page 5-3.The home areaIn distributed applications, the home area is the area in which an application component(e.g., a tag or display) is located. When you refer to an application component withoutspecifying the area, RSView uses the home area to locate the component.For example, if you create a graphic display in the Cooling area, and add a relativereference to a tag (for example, FanStart), RSView looks for the tag in the home area ofthe graphic display (Cooling). If the tag does not belong to a data server or HMI server inthe display’s home area, an error will occur when the display runs.The Tag Browser composes references to tags automatically, using correct syntax. If thetags you select are in the home area, the Tag Browser automatically uses relativereferences. If the tags are not in the home area, the Tag Browser uses absolute references.In the Tag Browser, thehome area appearsin bold type.Instead of browsing for tags, you can create references to tags manually, by typing the tagname and, optionally, its path.Logging tag valuesThe RSView data logger can log any tag value, and uses data log models to determinewhich values to log. For a tag to be polled and its values logged by the data logger, the tagneeds to be included in a data log model, and the model needs to be started at run time.For more information, see Help, or Chapter 13, Using data logging.8-12