GMC-I Messtechnik GmbH
R2700–21
Controller Sorts
Controller Sort
Applications
Fixed setpoint controller (
C In = nor)
Only the first measurement input is used for the controlled variable.
Differential controller (
C In = diff)
Actual value difference, i.e. 1
st
actual value versus 2
nd
actual value, is regulated to the selected differential
setpoint. The differential setpoint can be set within a range of
½ of the measuring range.
Limit value monitoring is relative to actual value difference, and not the two actual values.
Slave controller (
C In = SLA)
The external setpoint which is applied to the 2
nd
measurement input replaces the internal setpoint.
The setpoint ramp function is retained.
After switching to setpoint 2 (e.g. via binary input) the controller becomes a
fixed setpoint controller
using the
SP 2
setpoint.
Upper and lower limits for the external setpoint are scaled with the
rn L
and
rn H
parameters.
The
SP L
and
SP H
parameters limit the external setpoint for control and display purposes.
If an attempt is made at the operating level to change the setpoint (display mode: actual value / setpoint),
no
appears briefly at the bottom display.
Switch controller (
C In = SWit)
If a control loop has only one actuator and two sensors, and if the sensor to be used depends upon the operating
state, the switch controller can be used.
As long as “switch controller active” has not been selected, the first sensor and the first set of control parameters
(
Pb I
and
tu
) are active, as is also the case with fixed value control.
If “switch controller active” has been selected (e.g. via binary input), the second sensor and the second set
of control parameters (
Pb 2
and
tu 2
) are active. This state is indicated by a short blinking of the W2 LED.
Relative limit values are only monitored for the respectively active sensor, and absolute limit values are al-
ways monitored for both.
Ratio controller (
C In = rAti)
Both actual values are controlled to a fixed ratio. The second actual value is multiplied by the setpoint (as a
percentage) and used as a command value.
Mean value controller (
C In = MEAn)
The mean value = (1
st
actual value + 2
nd
actual valule)/2 is controlled to the fixed setpoint value.
Limit value monitoring refers to the mean value and not to the two actual values.
