Status message set

The base message for status records depends on whether the device is a two-state or a four-state device.

A two-state device only uses two messages: one state for the normal condition and the opposite state for the off-normal condition (for example, open and closed or vice versa). A four-state device may have an additional transit state when the unit is in the process of performing a state transition, and an error condition when the unit is not working.

Different message text groups are defined in the Message table according to the type of status device. The table below lists the messages that are typically used for the different states of a valve, a pump and a breaker. The text may vary to represent the interpretation of the various on/ open/start or off/close/stop states and the different error or transitional states.

Unless the Normally Open checkbox on the Input tab in the Status Row Edit dialog box is selected for the status point, an Open/Running/Trip state of a field device should never be described as a Close/Off state. For example, if the Close/Off state is used for a valve instead of the Open/Running/Trip state, the AVEVA Enterprise SCADA system interprets the valve state as Close when it is actually Open. Selecting the Normally Open checkbox for the status record inverts the sense when the status raw value is converted to its Engineering Unit (EGU) value.

Status alarm text

For two-state status records (for example, one-bit status) the middle two messages of the message set are used so that the same message set can be used for one-bit and two-bit status points. The second message in the set must be for the Open/Start/On/Trip state, and the third message must be for the Close/Stop/Off state. If the field device does not return a value of 1 to indicate the Open/Start/On/Trip state, then invert the sense of the status valve.