Chapter 3
Example Applications
©
National Instruments Corporation
3-11
FieldPoint FP-3000 User Manual
Select the Module and Channel
Determine the FieldPoint module number by counting each module in the
order it is attached to the FP-3000, beginning with one. In this example,
assume that the FP-TC-120 is the first module connected to the FP-3000,
and the FP-AO-200 is the second module. Therefore, set the value of
FIELDPOINT_MODULE
to
2
. Since the heating element is wired to the
terminals associated with channel zero on that module, set the
FIELDPOINT_CHANNEL
parameter to
0
.
Set the Output Range
1.
Find the
FP_AO_200_RANGE
parameter in the block.
2.
Set the parameter to a current range of
0–0.021 A
.
Scale the Output
1.
Tell the block the range of values to output to the transducer module.
Go to the
XD_SCALE
parameter in the block and enter the following:
XD_SCALE
EU at 100%
0.021
EU at 0%
0
Units Index A
Decimal
2
This tells the AO block to output readings in the range of 0 to 0.021 A
to the FP-AO-200 module.
You can avoid setting the
XD_SCALE
value manually if you set the
CFG_OPTS
option called Automatically adjust XD_SCALE. This
allows the FP-3000 to copy the value from
FP_AO_200_RANGE
straight into the
XD_SCALE
parameter.
2.
Determine the Process Variable (PV) scale. This scaling parameter is
used to convert from the units of Set Point (SP) to percent of scale. For
output function blocks like AO, SP is the value you want the block to
output. For this example, set
PV_SCALE
to 0 to 100 percent. With these
settings, a controller or operator changing the set point of this
AO block writes the percentage of scale, with 100% being maximum
output current.
PV_SCALE
EU at 100%
100
EU at 0%
0
Units Index %
Decimal
2