What is the meaning of the Quality value into the Trend Buffer dump file?

June 14, 2017 by Will Blackwell

What to know

The CSV file obtained from a Dump Trend Buffer operation is composed by many voices, the quality field reports information about the tag quality at the moment the samples has been taken.

The information is coded according the OPC DA standard; the information is stored in a byte data (8 bits) currently defined in the form of three bit fields; Quality, Sub status and Limit status. The 8 Quality bits are arranged as follows: QQSSSSLL

Quality Code	Quality	Description
0	BAD	The value is bad but no specific reason is known
4	BAD	There is some server specific problem with the configuration. For example, the tag in question has been deleted from the configuration file (tags.xml).
8	BAD	This quality may reflect that no value is available at this time, for reasons such as the value may have not been provided by the data source.
12	BAD	A device failure has been detected
16	BAD	Timeout occurred before device responded.
24	BAD	Communications have failed.
28	BAD	There are no data found to provide upper or lower bound value (trend interface specific flag).
32	BAD	No data have been collected (i.e. archiving not active. Trend interface specific flag). When the HMI return online after a reboot or from a condition where sampling stopped, a sample with quality value 32 is added to indicate this temporary offline status.
64	UNCERTAIN	There is no specific reason why the value is uncertain.
65	UNCERTAIN	There is no specific reason why the value is uncertain. (The value has ‘pegged’ at some lower limit)
66	UNCERTAIN	There is no specific reason why the value is uncertain. (The value has ‘pegged’ at some high limit.)
67	UNCERTAIN	There is no specific reason why the value is uncertain. (The value is a constant and cannot move.)
84	UNCERTAIN	The returned value is outside the limits defined for it. Note that in this case the “Limits” field indicates which limit has been exceeded but the value can move farther out of this range.
85	UNCERTAIN	The returned value is outside the limits defined for it. Note that in this case the “Limits” field indicates which limit has been exceeded but the value can move farther out of this range. (The value has ‘pegged’ at some lower limit)
86	UNCERTAIN	The returned value is outside the limits defined for it. Note that in this case the “Limits” field indicates which limit has been exceeded but the value can move farther out of this range. (The value has ‘pegged’ at some high limit.)
87	UNCERTAIN	The returned value is outside the limits defined for it. Note that in this case the “Limits” field indicates which limit has been exceeded but the value can move farther out of this range. (The value is a constant and cannot move.)
192	GOOD

We suggest to refer to Jmobile Studio Help to get further informations regarding all the voices present into the CSV file dumped.

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