Honeywell VRX180 Manuale Utente

 

Table 4-10   Loop Prompts (continued) 

ENGINEERING 

UNITS 

Select letter 

Units of measure for values of process variable or set point 
which will appear on Online loop displays. 

FEEDBACK 

OFF, analog parameter, 
number 

Provides verification to the loop that the loop output request 
(LP OV) was achieved by the analog output module (AO). 
Feedback sources are typically pointed to the associated 
Back Calculation Value (BC) of an analog output module. 
Feedback inputs must have a span equal to the loop output 
span when they are not pointed directly to analog output 
modules. 

FEEDFORWARD 

OFF, analog parameter, 
number 

Modifies the control loop output independent of the PID 
calculation. The range of the value should not exceed 0 to 
100 units. Feedforward is typically used to provide an output 
change in anticipation of a change to the loop process 
variable. 

FEEDFORWARD 

GAIN 

-10.00 to 10.00 

Applies gain to the feedforward input value. 

FORCE REMOTE 

MAN 

OFF, discrete parameter, 0, 
1 

When discrete is ON(1), forces loop from automatic mode to 
remote manual mode. In remote manual, loop output is 
determined by the OUTPUT TRACKING value and the local 
Down Arrow and Up Arrow buttons for manual output 
adjustment are disabled.  In remote manual the automatic 
indicator (AUTO) of the display will flash.  Selecting Manual 
mode from the Auto/Manual button will override remote 
manual operation. 

When the loop’s Set point #2 is programmed as the Set point 
Profiler (SPn OV), Force Remote manual should be 
programmed as OFF. 

GAIN/PROP BAND 

PB or GAIN 

Select whether gain or proportional band will be used for 
tuning the control loop. 

GAIN#1 OR GAIN#2 

Enter a value of 0.1 to 200 
for Gain, or 0.5 to 1000.0 for 
Proportional Band. Enter 
OFF to allow integral only 
control.  (Variable Gain1 or 
PB1 is available by 
programming a constant's 
Destination with GN or PB.  
See Program Constants, 
Section 4.16.) 

 

Gain is the proportional gain entry for the control loop (The 
value entered here is the gain applied to the error signal to 
determine the loop output). For example, a 10% change in 
process variable (with respect to the input range) from a 
balanced condition will result in a 10% change in output, 
when a gain of 1.0 is used. Enter a starting value at initial 
configuration. The value may be altered Online for final loop 
tuning. If an indirect source is specified as in an adaptive 
gain configuration, the value can only be altered at the 
source. 

Gain and Proportional Band are interchangeable values 
(Proportional Band = 100/Gain). For loops with dual tuning, 
Gain 1 is the gain for the first set of tuning parameters. Gain 
2 is for the second set. 

HYSTERESIS 

Enter 0-100% of PV span 

Deadband value prevents excessive output oscillation when 
using ON/OFF control.