Rate of Change Alarm is the amount a tag must change between scans that is considered too large. The ROC alarm is in Percent of SPAN. Value applies to both increase and decrease in tag's value (i.e. is symmetrical). The actual rate is a function of this vale and the Scan Rate of the device. If the device scans Once per Second, then rate is change per second. If device scans at 100 milliseconds, then Rate of Change = 10 is also once per second. Rate of Change alarming is the idea that a measurement is changing too fast. For example, flow in a pipe causing cavitations. This field is for ANALOG tags and parameters only.
0 to 100
Units: percent of span
Configuration: Rate of Change - ROC
Field Type: Analog
Tag field: .ALMROC