Mapping quality codes to system digital states
- Last UpdatedDec 28, 2022
- 2 minute read
The optional quality property contains an OPC quality code from section 6.8 of the OPC Data Access Custom Interface Specification (version 3.0). The low-order eight bits of the quality code are grouped into three fields: QQSSSSLL, where the QQ bits indicate overall quality. The SSSS bits are called the substatus field and interpretation depends on the QQ bits. The LL bits are the limit field and interpretation depends on the QQSSSS bits.
When the optional quality property is present in a value stream, the quality code applies to all measurement properties in the stream and determines what is stored in the PI point for each measurement property in the stream.
In the following table, the first column contains OPC quality codes in binary representation. An "x" in a bit position indicates that the state of the bit is ignored.
The second column contains the OPC short definition of the quality code.
The third column lists the archive event that the relay sends to Data Archive for each quality code. The state names are Data Archive System digital states.
For quality codes that are not in the table, the relay sends a Bad Input System digital state event.
|
Code |
Description |
Archive event |
|---|---|---|
|
11 xxxx xx |
Good overall quality |
Measurement is archived. |
|
01 0000 xx |
Uncertain, non-specific |
Measurement is archived with Questionable bit set. |
|
01 0001 xx |
Last Usable Value |
No_Sample state |
|
01 0100 00 |
Sensor Not Accurate |
Invalid Data state |
|
01 0100 01 |
Sensor Not Accurate |
UnderRange state |
|
01 0100 10 |
Sensor Not Accurate |
Over Range state |
|
01 0100 11 |
Sensor Not Accurate |
Invalid Data state |
|
01 0101 00 |
Engineering Units Exceeded |
Inp OutRange state |
|
01 0101 01 |
Engineering Units Exceeded |
Under LCL state |
|
01 0101 10 |
Engineering Units Exceeded |
Over UCL state |
|
01 0101 11 |
Engineering Units Exceeded |
Inp OutRange state |
|
01 0110 xx |
Sub-Normal |
Bad_Quality state |
|
00 0000 xx |
Bad, non-specific |
Bad state |
|
00 0001 xx |
Configuration Error |
Configure state |
|
00 0010 xx |
Not Connected |
Not Connect state |
|
00 0011 xx |
Device Failure |
Unit Down state |
|
00 0100 xx |
Sensor Failure |
Equip Fail state |
|
00 0101 xx |
Last Known Value |
Scan Timeout state |
|
00 0110 xx |
Comm Failure |
Comm Fail state |
|
00 0111 xx |
Out of Service |
Out of Serv state |
|
00 1000 xx |
Waiting for Initial Data |
Bad Input state |