Supplementary Documentation
Page 32 of 44
IFC090, IFC090 i with FF
IFC090-FF Configuration
IFC090 FF 01/2005
KROHNE Messtechnik GmbH & Co. KG · Ludwig-Krohne-Str. 5
D-47058 Duisburg
Tel.: 0203-301 309
Fax: 0203-301389 · E-mail: krohne@krohne.de
Parameter calculation:
EUat100[XD_SCALE] =
100.0
EUat0[XD_SCALE] = 0.0
UnitsIndex[Units Index] =
m3/s
Euat0[OUT_SCALE] =
0.0
UnitsIndex[OUT_SCALE] = ft3/min
⇒
EUat100[OUT_SCALE] = (100.0 * 1,000) = 100,000.0
Indirect Square Root
Square root conversion. Takes the square root of the value computed by applying the input scaling
(XD_SCALE) to the value obtained from the Transducer and maps the result to the output scaling
(OUT_SCALE).
5.3.3 Filtering
The parameter PV_FTIME can be used to flatten the output value OUT in case of rapid changes in the channel
value obtained from the Transducer. The higher the value in PV_FTIME in unit seconds, the slower the rise in
the output value. If PV_FTIME is set to 0, no filtering will be performed.
Important Note:
Applications with pulsating flow as well with rapid changes in flowrate may require special settings in order to
smooth and stabilize the flow as indicated in the display (see section 6.4 and 6.5 of the IFC090 Installation and
Operating Instruction)
The flow input value for the FF module is based on that smoothed flow value indicated in the display (beginning
with Device Series No. 429 861). When making use of the PV_FTIME parameter in the AI Block, you should be
aware that there are two filters in series (filter in the device and filter AI Block).
5.3.4 Input/Output
Options
The Fieldbus Foundation specification provides some different options for affecting the in- and outputs of
Function Blocks in parameter IO_OPTS. But only one of these options is applicable to an Analog Input Block:
“Low cutoff”.
If the Low Cutoff option is enabled and the converted block’s input value (PV) is below the limit specified by
parameter LOW_CUT, a value of zero (0) is used for the PV.
This is useful to eliminate leak flow volumes around zero.
5.3.5
Output Status Options
The status value of the output OUT offers valuable clues to the quality of the measurement value. While this
status most extensive depends on the state of the measurement electronics and the measurement process
itself. By setting some of the following options in parameter STATUS_OPTS, the user is able to give this status
an own interpretation on a small scale:
