During limit/range monitoring, a group of 6 bits is manipulated in the process variable defined as the output variable.

Each time one of the 6 limits is exceeded, the corresponding assigned bit is set (see Limits parameter).

In range monitoring, the limits divide the variable range into a normal range and up to 6 monitoring ranges. No bit is set in the normal range (between limit L/H). Outside this range, the corresponding bit assigned to the range is set. This means that only one bit is ever active.

In limit value monitoring, the 6 limits are checked individually. If the variable value to be monitored is higher/lower than an upper/lower limit, the corresponding bit is set. This means that several bits can be active at the same time.

An internal variable is usually used as the output variable. However, if monitoring events are to be reported back to the controller, an external variable (a variable in the corresponding communication component) can also be used.

If centralised recording of monitoring events in the alarm system is required, the output variable can be used as an event variable for alarms.

The variable defined as the output variable must be of an integer data type.

Parameters for

Process data monitoring module:

Monitoring