Limits and Reaction Matrices

Limits define, when an alarm occurs. The limit value is defined through certain conditions of bit variables, through value ranges of analog variables, or through conditions of string variables. Various attributes alter the display of graphical elements: flashing, invisible, color change.

Each threshold value violation can be defined as an alarm and/or an entry in the Chronological Event List (CEL). For automatic, event controlled reactions those conditions can be linked with actions. In regard to alarms the linked function can optionally be carried out through the press of a button on an alarm picture.

Clarity with hysteresis and threshold values

In order to have a clear overview it is important that so called fluttering messages that occur through continuous short term reaching of threshold values, are suppressed whenever possible. Here zenon offers several possibilities:

• through delay times: only when a value occurs long enough, is it considered.
• related to a value (hysterisis): Only when a value change lies over/below this hysterisis (flatline), it is sent to zenon by the driver and thereby taken into account.

Furthermore threshold values can be defined so that the critical value violation is only cancelled if the reached value exceeds or falls below the threshold value.

Reaction matrices (REMAs)

Alarms can also be defined through reaction matrices. In contrast to critical values the ReMas are centrally managed and an unlimited number of variables can be assigned to a ReMa. In addition to the possibilities offered by the critical value definition, it is also possible with reaction matrices to react to bit patterns of analog variables and to analyze status information.