National Instruments FP-3000 - Manual (Page 49)

Chapter 3 Example Applications
FieldPoint FP-3000 User Manual 3-14 www.ni.com
Scale the PID
Double-click on the PID block you created to launch the block
configuration window. Set the
PV_SCALE parameter on the Scaling tab.
The PV_SCALE should match the output scale ( OUT_SCALE ) of the AI block
because you will wire the output of the AI block to the IN (i.e., process
variable) of the PID block. Enter the following:
PV_SCALE
EU_100 1775
EU_0 -273
Units_Index °C
Decimal 2
When you set the PV_SCALE for the AO block, you set it to take 0 to 100
percent, so adjust the PID block to output that range. To set the OUT_SCALE
parameter of the PID, enter the following:
OUT_SCALE
EU_100 100
EU_0 0
Units_Index %
Decimal 2
Set Up Scheduling
Before the block will operate, you need to schedule the block to execute.
All Fieldbus function blocks (including function blocks on the FP-3000)
execute according to a schedule. You can specify the order of function
blocks in the schedule and the rate at which the schedule is repeated. If the
Function Block Application Editor window is not already open,
double-click on Function Block Application in the configuration tree of
the NI-FBUS Configurator.
Connect the PID to the AI and AO Blocks
Drag your AI, AO, and PID blocks from the configuration tree to the
Function Block Application Editor window, if you have not done so
already. The NI-FBUS Configurator automatically generates a schedule for
the blocks that causes them to run every second (refer to the documentation
that came with your NI-FBUS Configurator for information about
changing the execution period).