Quality

Quality of data value

Description

Quality indicates the quality of the daitem object’s Value property as a character vector. You can use the Quality property to determine if a value is useful or not.

The Quality is made up of a major quality, a substatus, and an optional limit status, arranged as a character vector in the format 'Major: Substatus: Limit status'. The limit status part is omitted if the value is not limited. The major quality can be one of the following values:

Value

Description

Bad

The value is not useful for reasons indicated by the substatus.

Good

The value is of good quality.

Uncertain

The quality of the value is uncertain for reasons indicated by the Substatus.

For a list of substatus and limit status values and their interpretations, consult OPC Quality.

Quality is updated when you perform a read operation using read or readasync, or when a subscription callback occurs. Quality is also returned during a synchronous read operation.

Characteristics

Access

Read-only

Applies to

daitem

Data type

character vector

Values

The default value is 'Bad: Out of Service'.