Function Blocks
Function Block Reference Guide
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2.50 PID Function Block,
continued
Configuration Parameters,
continued
Table 2-39 General Tab Configuration Parameters
Properties
Group
Parameter
Index#
Parameter
Description
Value or Selection
Block
Order
N/A
Execution Order
Read Only. See “Configure’ Menu, ”Execution
Order” to change.
Tag Name
N/A
8 character tag name
Descriptor
N/A
Block descriptor
Control
Algorithm
N/A
Control Algorithm
Note: In PID B, step
changes in setpoint
will not bump the
output; the output
will slew tosmoothly
to the new value.
In PID A, a step
change in setpoint
will result in a step
change in output
.
PID A
- is normally used for 3 mode
control. The output can be adjusted
somewhere between 100% and 0%. It
applies all three control actions -
Proportional(P), Integral(I), and
Derivative(D) - to the error signal.
PID B
- Unlike the PID-A equation, the
controller gives only an integral
response to a setpoint change, with no
effect on the output due to the Gain or
Rate action, and gives full response to
PV changes.
DUPA -
like PID A but provides an
automatic method to switch tuning
constant sets for Heat/Cool
applications.
DUPB -
like PID B but provides an
automatic method to switch tuning
constant sets for Heat/Cool
applications.
ATTENTION
With PID B or DUPB
selection, you
will not
be allowed to
set RESETor RPM to 0.00 (OFF).
Reset must be enabled.
Direction
N/A
Control Action
DIRECT
- PID action causes output to
increase
as process variable
increases.
REVERSE
- PID action causes output
to
decrease
as process variable
increases.
SP
Tracking
N/A
Setpoint Tracking
None
Track PV
When control mode is
“manual”, local
setpoint
tracks
process variable.
Track RSP
When
setpoint
is “remote
setpoint
”, local
setpoint
tracks
remote
setpoint
.
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