About quality states

Good

Nonspecific

The quality is good.

Uncertain

Nonspecific

The quality is neither good nor bad.

Bad

Nonspecific

There is no specific reason why the value is of this quality.

Bad

ConfigurationError

There is some server specific problem with the configuration. For example the item in question is deleted from the configuration.

Bad

NotConnected

The input is required to be logically connected to something but is not. This quality may reflect that no value is available at this time, for reasons like the value is not provided by the data source.

Bad

DeviceFailure

Bad

SensorFailure

A sensor malfunction is detected. The Limit can provide additional diagnostic information in some situations.

Bad

LastKnownValue

Communications were interrupted. However, the last known value is available. Note that the age of the value may be determined from the Timestamp.

Bad

CommFailure

Communications were interrupted. There is no last known value available.

Bad

OutOfService

The block is off scan or otherwise locked. This quality is also used when the active state of the item or the group containing the item is inactive.

Bad

Overflow

Occurs when an arithmetic, casting, or conversion operation results in an overflow.

Bad

LastUsableValue

Whatever was writing this value has stopped doing so. The returned value should be regarded as stale. Note that this differs from LastKnownValue. That status is associated specifically with a detectable communications error on a fetched value. This error is associated with the malfunction of some external source to put something into the value in an acceptable period of time. Note that the age of the value can be determined from the Timestamp

Bad

SensorNotAccurate

Either the value has pegged at one of the sensor limits (in which case the Limit should be set to LowLimited or HighLimited) or the sensor is otherwise known to be out of calibration through some form of internal diagnostics (in which case the Limit should be NotLimited).

Bad

EngineeringUnitsExceeded

The returned value is outside the limits defined for this parameter. Note that in this case the Limit indicates which limit is exceeded but does NOT necessarily imply that the value cannot move farther out of range.

Bad

Subnormal

The value is derived from multiple sources and has less than the required number of Good sources.

Bad

LocalOverride

The value was overridden. Typically this is means the input is disconnected and a manually entered value is "forced".

Bad

DataNotAvailable

Data was not available to create a boundary sample.

Bad

DBNull

The returned value was DBNull, so the last known good value is retained with its quality and substatus reset.

Bad

Disabled

The value is disabled.

Bad

InvalidTypeConversion

Cannot convert a value from one type to another

Bad

Stopped

The value is stopped.

Bad

Uninitialized

The value is not initialized.