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The quality of a given OPC tag is used to represent the validity of the tag's value (in other words, whether or not an OPC client can trust the data). OPC quality is divided into three main categories: Good (generally indicates the data is valid), Bad (generally indicates the data is not valid), or Uncertain (generally indicates the data is speculative in some manner). Each category is further divided into sub-categories; the exact criteria for using a particular sub-category may vary depending on the end protocol and vendor, however the list below provides a good starting point for further investigation.

OPC DA Quality Codes

0

0x00000000

Bad [Non-Specific]

4

0x00000004

Bad [Configuration Error]

8

0x00000008

Bad [Not Connected]

12

0x0000000c

Bad [Device Failure]

16

0x00000010

Bad [Sensor Failure]

20

0x00000014

Bad [Last Known Value]

24

0x00000018

Bad [Communication Failure]

28

0x0000001C

Bad [Out of Service]

64

0x00000040

Uncertain [Non-Specific]

65

0x00000041

Uncertain [Non-Specific] (Low Limited)

66

0x00000042

Uncertain [Non-Specific] (High Limited)

67

0x00000043

Uncertain [Non-Specific] (Constant)

68

0x00000044

Uncertain [Last Usable]

69

0x00000045

Uncertain [Last Usable] (Low Limited)

70

0x00000046

Uncertain [Last Usable] (High Limited)

71

0x00000047

Uncertain [Last Usable] (Constant)

80

0x00000050

Uncertain [Sensor Not Accurate]

81

0x00000051

Uncertain [Sensor Not Accurate] (Low Limited)

82

0x00000052

Uncertain [Sensor Not Accurate] (High Limited)

83

0x00000053

Uncertain [Sensor Not Accurate] (Constant)

84

0x00000054

Uncertain [EU Exceeded]

85

0x00000055

Uncertain [EU Exceeded] (Low Limited)

86

0x00000056

Uncertain [EU Exceeded] (High Limited)

87

0x00000057

Uncertain [EU Exceeded] (Constant)

88

0x00000058

Uncertain [Sub-Normal]

89

0x00000059

Uncertain [Sub-Normal] (Low Limited)

90

0x0000005a

Uncertain [Sub-Normal] (High Limited)

91

0x0000005b

Uncertain [Sub-Normal] (Constant)

192

0x000000c0

Good [Non-Specific]

193

0x000000c1

Good [Non-Specific] (Low Limited)

194

0x000000c2

Good [Non-Specific] (High Limited)

195

0x000000c3

Good [Non-Specific] (Constant)

216

0x000000d8

Good [Local Override]

217

0x000000d9

Good [Local Override] (Low Limited)

218

0x000000da

Good [Local Override] (High Limited)

219

0x000000db

Good [Local Override] (Constant)

 


 OPC HDA Quality Codes

65536

0x00010000

Bad [Non-Specific] : Extra Data

65540

0x00010004

Bad [Configuration Error] : Extra Data

65544

0x00010008

Bad [Not Connected] : Extra Data

65548

0x0001000c

Bad [Device Failure] : Extra Data

65552

0x00010010

Bad [Sensor Failure] : Extra Data

65556

0x00010014

Bad [Last Known Value] : Extra Data

65560

0x00010018

Bad [Communication Failure] : Extra Data

65564

0x0001001c

Bad [Out of Service] : Extra Data

65600

0x00010040

Uncertain [Non-Specific] : Extra Data

65601

0x00010041

Uncertain [Non-Specific] (Low Limited) : Extra Data

65602

0x00010042

Uncertain [Non-Specific] (High Limited) : Extra Data