Glossary
9–7
IP244
C79000–Y8576–C858–02
Secondary control loop
Secondary control loop, whose setpoint is influenced by a master
controller in cascaded control.
Self-tuning
Based on a mathematical quality criteria, the controller
parameters are matched to the existing task automatically to
achieve an optimum controller action.
Setpoint jump (step)
Entry of a new setpoint with a value different from the old setpoint.
Setpoint ramping
To damp setpoint jumps, the setpoint is not changed suddenly but
follows a selectable ramp slope.
Setpoints
Desired (demanded) process value to be maintained by the
controller.
Software release
Release of the operating program in the EPROM of the module.
Special function
Special mode which controls the read-in of measured values via
the channels 13 and 14 in a way, which makes it possible to
acquire series of measured values in curved form (channel 13)
and to allocate a measured value from channel 14.
Status (byte)
Eight-bit information unit; each bit is assigned to a particular error
(1 = error).
Symmetrical/asymmetrical
If the measurement equipment (here, thermocouple) is arranged
controlled systems
symmetrically to the actuators for the heating or cooling, the
controlled system is symmetrical, otherwise it is asymmetrical
(e.g. extruder heating with unequally divided heating band and
thermocouple between).
System deviation x
d
Difference between the entered setpoint and measured actual
value (input variable of the controller).
T
A
Sampling time
T
D
Derivative action time (describes the D action).
Temperature compensation
When measuring temperatures with thermocouples, the voltage
produced by the thermocouple is proportional to the temperature
difference between the measuring junction and the reference
junction. The temperature compensation value is required to
compensate the ambient temperature at the reference junction, to
obtain a temperature value related to 0 C.
Thermocouple
Temperature sensor consisting of two different metals (e.g. iron,
constantan); supplies a voltage dependent on the temperature
difference between the measuring junction and the reference
junction.
Three-step controller
Controller with two switching contacts as output (heat, off, cool,
or right, off, left = three switching statuses).
Three-wire connection
Method of connecting resistance thermometers to compensate
the influence the lead resistances.
T
N
Integral action time (describes the integral action of the
controller).
Tolerance values
Temperature values above and below the required temperature
(setpoint). If these tolerances are violated, signals are generated
by the control variable so that corrective action can be taken.
Transfer RAM
Memory on the IP 244; can be written to and read from both by the
programmable controller and by the microprocessor on the
module.
Two-step controller
Controller with one switching contact as its output (two switching
statuses).
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