RSView Supervisory Edition Installation Guide

• • • • •RSVIEW SUPERVISORY EDITION USER’S GUIDEUsing HMI tagsUse HMI tags for triggering alarms and where you need to manipulate data or secure thevalues in a device.Triggering alarmsIn RSView, HMI tags provide the only method for triggering an alarm when a tag has acertain value.An alarm occurs when something goes wrong. It can signal that a device or process hasceased operating within acceptable, predefined limits or it can indicate breakdown, wear,or a process malfunction.For more information about alarms, see Chapter 11, Creating alarms.Securing tag or device valuesOnly HMI tags can be used to secure tag or device values.To prevent users from changing a value in a device, create an HMI tag for the device’saddress, and then assign a security code to the tag.For information about assigning security to tags, see “Assigning security codes to HMItags” on page 15-29.Manipulating dataUse HMI tags if the data server you are using does not support scaling or offsetting of tagvalues, or setting minimum or maximum limits for tag values (that is, providing a range ofvalues).Scale, offset, and minimum and maximum values can be specified in the Tags editor, foranalog HMI tags.Scale and offsetUse scale and offset to modify the raw data that comes from the network device before itis saved in the computer’s memory, or to modify a value specified in RSView before it iswritten to a device or data serverScale is a multiplication factor—the value from the device is multiplied by the scale.Offset is a fixed value—after the value from the device is multiplied by the scale, theoffset amount is added.8-4