Pid control, Block instantiation and deletion, Pid control -3 block instantiation and deletion -3 – National Instruments FP-3000 User Manual
Page 16
Chapter 1
FP-3000 Network Module Overview
© National Instruments Corporation
1-3
FieldPoint FP-3000 User Manual
to form a distributed control system. Function blocks can perform PID
calculations, logic operations, read an input channel, write an output
channel, or a number of other functions.
The FP-3000 implements F
O U N D A TIO N
Fieldbus–compliant I/O function
blocks, such as Analog Input (AI), Analog Output (AO), Discrete Input
(DI), and Discrete Output (DO). These blocks provide functionality such as
scaling, trending, and alarming. For example, when you connect a
4–20 mA pressure transmitter to a FieldPoint I/O, you can configure an
FP-3000 Analog Input function block to convert from 4–20 mA to
engineering units. You can set up alarm limits so that the FP-3000 sends an
alarm when the pressure exceeds the limits. The FP-3000 network module
can also collect trend samples and broadcast them to applications on a PC.
For more information on function blocks, refer to Chapter 4,
PID Control
The FP-3000 implements a F
O U N D A TIO N
Fieldbus–compliant PID control
function block. This PID can be used to control either an analog output
element connected to FieldPoint I/O or a native Fieldbus device, such as a
valve, connected to the Fieldbus network. The FP-3000 executes the PID
and other function blocks deterministically in accordance with the schedule
configured by the NI-FBUS Configurator and/or the user. For more
information on PID control, refer to Chapter 4,
.
Block Instantiation and Deletion
You can instantiate (create copies of) or delete the PID function block on
an as-needed basis. For example, if you are adding a new loop to an existing
Fieldbus network, you can instantiate a PID function block in the FP-3000
to control the loop. You can also instantiate the I/O function blocks on an
as-needed basis. If you have an 8-channel Analog Input module and you are
using only two channels, you can save memory by instantiating only two
AI function blocks. You can instantiate additional AI function blocks when
you use additional channels. National Instruments recommends
instantiating additional AI function blocks if you will be approaching the
150 block limit. For instruction, refer to the section
in Chapter 3,