West Control Solutions MRC 8000 - Manual (Page 67)

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Appendix B
Glossary
Automatic Reset (Integral)
This parameter is used so that the instrument will compensate for process variable deviations
from setpoint that occur when the process load characteristics change. Instructions for
determining the automatic reset settings are given in Table 3-2 (Page 34). Factory default
is.0.0. Display code ArSt.
Automatic Transfer
This feature, if configured, allows manual control of the process until setpoint is reached, at
which point the controller automatically transfers from manual to automatic control. Factory
default value is 0 = no auto transfer. Display code AtFr.
Bumpless Transfer
This feature prevents step changes in proportional outputs when changing from automatic to
manual control only.
Cycle Time
This Tune mode parameter is used to select the on/off cycle time for time proportioning
outputs (Ct1 for Output 1 and/or Ct2 for Output 2).
When usng the Position Proportioning option, Ct1 must be selected for the stroke time of the
motor.
Display Filter Factor
This parameter is adjustable from 1 to 20 which represents the number of scans per second
of the process variable that are averaged together before updating the displayed and re-
corded value. The factory default value is 1 = no filtering. Display code dFF.
Engineering Units Upper and Engineering Units Lower
These Program mode parameters are used with volt, millivolt, and milliamp inputs. The
Engineering Units Upper Euu should be selected as the value to be displayed when the input
is at maximum. The Engineering Units Lower EuL should be selected as the value to be
displayed when the input is at minimum.
First Output Position
This parameter is adjustable from -1000 to 1000 units and represents a shift or offset of the
on-off actuation points or proportional band for the first output relative to the normal position.
For example, a negative value could be used to offset an expected overshoot. First Output
Position also shifts the proportional band with respect to the process value range outside of
which integral action is inhibited. Factory default is 0. Display code FoP.
Hysteresis
This parameter is adjustable from 0 to 300 units representing the width of the band (half
above and half below setpoint). Used with ON/OFF or Alarm outputs to reduce cycling. For
instance, with a value of 4 and a setpoint of 70 the output will turn ON when the process
variable drops to 68 and stay ON until 72 is reached, then turn OFF the output. Factory
default = 3. Display code HyAo for Alarm outputs. Display code HyCo for ON/OFF Control
outputs.
Input Correction
This parameter is adjustable from -300 to 300 units and is used as a method to compensate
for a linear sensor error. Factory default is 0 = no correction. Display code iCi1, iCi2.
Manual Reset
This parameter is adjustable from -1500 to 1500 units representing a manual shift of propor-
tional band(s) relative to the normal position which is an even strattle of the setpoint. Manual
reset is intended to be used when automatic reset is not used to allow compensation for
deviations from setpoint which remain after the process has stabilized. Factory default is 0.
Increasing the value increases the process variable, i.e. if the process variable stabilizes too
low, increase the manual set. Integral action, and conversely reset-windup inhibit apply over
the same process value range regardless of the manual reset value. Display code rSEt.