3
COMMISSIONING / OPERATION
16
VFC 200
www.krohne.com
06/2019 - 4005059401 - AD VFC200 PB-PA R01 en
Check the first two quality bits in order to get the quality information of the measurement value:
•
Good (Non Cascade):
Good (Non Cascade):
Good (Non Cascade):
Good (Non Cascade): function block output value is ok and can be used without restrictions
•
Good (Cascade):
Good (Cascade):
Good (Cascade):
Good (Cascade): will not be supported, because it is not applicable for the device
•
Uncertain:
Uncertain:
Uncertain:
Uncertain: function block output value can be used but the accuracy can not be guaranteed
(e.g. function block outputs value has been frozen or A/D converter is saturated or out of
range)
•
Bad:
Bad:
Bad:
Bad: function block output value is bad - don't use it for process control!
The "Quality-Substatus" and "Limit" bits will be used for further diagnostics or limit checking.
Quality
Quality substatus
Limits
Gr
Gr
QS
QS
QS
QS
Qu
Qu
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
1
0
0
0
0
0
x
x
= ok
1
0
0
0
0
1
x
x
= update event
1
0
0
0
1
0
x
x
= advisory alarm
1
0
0
0
1
1
x
x
= critcal alarm
1
0
1
0
0
0
x
x
= initiate fail safe (not provided by signal converter)
1
0
1
0
0
1
x
x
= maintenance required
1
0
1
0
1
0
x
x
= maintenance demanded
1
0
1
1
1
1
x
x
= function check
Table 3-5: Coding for "Status = good (Non Cascade)"
Quality
Quality substatus
Limits
Gr
Gr
QS
QS
QS
QS
Qu
Qu
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
0
0
= ok
0
1
= low limited
1
0
= high limited
1
1
= constant
Table 3-6: Coding for "Status = Limits"
INFORMATION!
The status should be monitored because a number will be transmitted even if the status of the
measurement value is bad or uncertain. This is the only way to check the quality of the
transmitted measurement values.
