OPC Quality Flags

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Geo SCADA uses OPC standard quality definitions for the many quality database fields, including 'CurrentQuality' and 'PreviousQuality' point fields (also for 'PutAsideQuality' in ClearSCADA 2007 R1 and later). By using the relevant mask you can get at the quality, status and limit bits:

31 30 29 28    27 26 25 24    23 22 21 20    19 18 17 16     15 14 13 12    11 10 09 08    07 06 05 04    03 02 01 00   
[             Historic Data Access Quality             ]     [                Data Access Quality                   ]                                                                                              
                                                             [ Q ] [     S      ] [ L ]

Where:

• Q is the (Data Access) Quality Field.
• S is the (Data Access) Status Field.
• L is the (Data Access) Limit Field.

Quality Field

Quality Mask

Dec Hex 
192 0xC0 -------------------- OPC Quality Mask

Quality Bit Fields

Dec Hex   
0 0x00 -------------------- Bad                
64 0x40 -------------------- Uncertain        
192 0xC0 -------------------- Good

Status Field

Status Mask

Dec Hex 
252 0xFC -------------------- OPC Status Mask

Status Bit Fields

Dec Hex   
4 0x04 -------------------- Bad - Configuration Error in Server   
8 0x08 -------------------- Bad - Not Connected  
12 0x0C -------------------- Bad - Device Failure  
16 0x10 -------------------- Bad - Sensor Failure  
20 0x14 -------------------- Bad - Last Known Value Passed  
24 0x18 -------------------- Bad - Comm failure  
28 0x1c -------------------- Bad - Item Set InActive          
32 0x20 -------------------- Bad - Waiting for Initial Data  
68 0x44 -------------------- Uncertain - Last Usable Value - timeout of some kind  
80 0x50 -------------------- Uncertain - Sensor not Accurate - outside of limits  
84 0x54 -------------------- Uncertain - Engineering Units exceeded  
88 0x58 -------------------- Uncertain - Value from multiple sources - with less then required good values 
216 0xD8 -------------------- Good - Local Override, Value Forced

Limit Field

Limit Mask

Dec Hex   
3 0x03 -------------------- OPC Limit Mask

Limit Bit Fields

Dec Hex   
0 0x00 -------------------- Ok   
1 0x01 -------------------- Low   
2 0x02 -------------------- High   
3 0x03 -------------------- Const             

Historic Data Access Quality

Dec Hex   
1 0x00010000 -------------- More than one piece of data that may be hidden exists at same timestamp.     
2 0x00020000 -------------- Interpolated data value.    
4 0x00040000 -------------- Raw data value.   
8 0x00080000 -------------- Calculated data value, as would be returned from a ReadProcessed call.    
16 0x00100000 -------------- No data found to provide upper or lower bound value.    
32 0x00200000 -------------- No data collected. Archiving not active (for item or all items).    
64 0x00400000 -------------- Collection started / stopped / lost.    
128 0x00800000 -------------- Scaling / conversion error.    
256 0x01000000 -------------- Aggregate value is for an incomplete interval. 

Visual Representation

                                                             [                Data Access Quality                   ]                                                                      15 14 13 12    11 10 09 08    07 06 05 04    03 02 01 00      															                                                                                                                [ L ]     Limit Bits                                                                                                                0   0     Not Limited                                                                                                                0   1     Low Limited                                                                                                                1   0     High Limited                                                                                                                1   1     Constant                                                                                                                                                                                                                  [ Q ] [     S      ]            Quality and SubSatus                                                                                           0  0 [     S      ]            Bad Quality                                                                                                 0  0     0  0            Non Specific                                                                                                 0  0     0  1            Configuration Error                                                                                                 0  0     1  0            Not Connected                                                                                                 0  0     1  1            Device Failure                                                                                                 0  1     0  0            Sensor Failure                                                                                                 0  1     0  1            Last Known Value                                                                                                 0  1     1  0            Comm Failure                                                                                                 0  1     1  1            Out of Service                                                                                                 1  0     0  0            Waiting for Initial Data                                                                                                 1  x     x  x            (S9-S15 is Reserved)                                                                                                                                                                                                                   0  1 [     S      ]            Uncertain                                                                                                 0  0     0  0            Not Specified                                                                                                 0  0     0  1            Last Used Value                                                                                                 0  0     1  x            (Not used in OPC)                                                                                                 0  1     0  0            Sensor Not Accurate                                                                                                 0  1     0  1            Engineering Unite Exceeded                                                                                                 0  1     1  0            Sub-Normal                                                                                                 .  .     .  .            (S7-S15 is Reserved)                                                                                                                                                                                                                   1  0 [     S      ]            (Not used in OPC)                                                                                                                                                                                                                   1  1 [     S      ]            Good                                                                                                 0  0     0  0            Not Specified                                                                                                 .  .     .  .            (S2-S5 are not used in OPC)                                                                                                 0  1     1  0            Local Override                                                                                                 .  .     .  .            (S7-S15 is Reserved)                                                                                                                        [             Historic Data Access Quality             ]        31 30 29 28    27 26 25 24    23 22 21 20    19 18 17 16                                                                                                                                                                                                                                                                                                       1                                                                  More than one data on this timestamp                                                    1                                                                     Interpolated                                                 1                                                                        Raw Data Value                                              1                                                                           Calculated                                        1                                                                                 No data found to provided upper or lower bound value                                     1                                                                                    No data found                                  1                                                                                       Data Lost - Collection started/stoped/lost                               1                                                                                          Scaling/Conversion Error                         1                                                                                                Aggregate Value is for an incomplete interval

This information was taken from:

• OPC Data Access Custom Interface, Version 3.0, section 6.8 (page 160)
• OPC Historical Data Access Specification, Versions 1.2, section 5.1 (page 112).

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