Glossary
IP244
C79000–Y8576–C858–02
9–6
P
Proportional action of the controller.
Parallel structure
Special type of controller structure (here: mathematical
technique); P, I and D sections act in parallel and are then added.
Parameter
Variables used to adapt the controller structure and the controller
action to the process.
Peripheral (I/O) area
Address area for peripheral modules in the programmable
controller.
Percentage output
The output of the calculated manipulated variable (output signal
of the controller) as a percentage of the sampling time referring
to the approach time (cf. ”Pulse Duration Modulation”).
PESP
Group address signal on the S5 bus to address peripheral
modules.
PLC
Programmable controller
Process identification
Acquisition of characteristic values of a particular system
(characterics of the control system) to optimize the tuning of the
controller action.
Pt 100
Platinum resistance thermometer (100 Ohms at 0 C according to
DIN 43760).
Pulse duration modulation
See ”Percentage Output”.
RAM
Random access memory (working memory); can be read to and
from.
Ramp slope
Here, preset rate of temperature rise per time unit.
Reference junction
Reference temperature for the thermocouple voltage
temperature
(see ”Thermocouple”).
Reference potential
Central grounding point of the controller.
Response value Y
A
If the manipulated variable is close to 0 or 100%, the short ON and
OFF intervals can be suppressed by specifying a parameter (e.g.
an ON time for a fan of 100 ms is completely pointless). See
Programming Instructions for the IP 244, ”messages 0 ... 12”.
Rugged controller
The rugged controller is a PID controller with supplementary
characteristics: it has an oscillation detector and a so-called
predictor, i.e. the actual value to be expected is calculated in
advance, and the controller reacts accordingly ”foresightedly”.
The controller parameters of the rugged controller depend on the
operating point and the current system deviation.
Sampling controller
A controller which processes a new actual value at regular
intervals and calculates a new manipulated variable.
Sampling time T
A
Period between two processing cycles of the PID calculation
program for one control channel. These periods are constant and
selectable within limits.
Sampling time overflow
The sampling time calculated for the controller can no longer be
maintained owing to excessive data exchange.
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