User Manual For - CONTROLLER/DATA RECORDER MultiCon CMC-99/141
A logical channel operating as a PID controller generates an "analog" output signal. This
signal can be limited to a range suitable for an output used. On the other hand all built-in
outputs have settings allowing to fit them to a source signal (see
PWM (Pulse-width modulation) mode for SSR relay output
). It is the user's responsibility to choose a correct limitation of a PID output
(as well as other PID settings), but it is important to set a limitation range wide enough to
obtain smooth controlling of the actuator, and narrow enough to make PID as fast as possible.
We can assume that the PID output range is set as 0-100. To set this, the user should enter
the
Controller
menu, select a requested controller and in the
Controller output
parameters
block set:
Offset
: 0,
Low output limit
: 0,
High output limit
: 100,
Other PID controller settings depend only on the application.
Let's assume that the user has to use the TC signal (K) for temperature measurement
(module TC4 installed in slot A) and the SSR output driver (module S8 installed in slot C) to
control a heater keeping a set temperature of the object. Let's assume that the temperature
setpoint can be set between 120 and 200
C.
To realise this task the user needs at least 3 logical channels and 1 set of Controller settings.
Logical channel 1 – Measurement of temperature,
Logical channel 2 – Setpoint of temperature,
Logical channel 3 – PID controller,
Controller 1 – settings of PID controller which runs in channel 3,
There are a few basic, well known methods described in the literature to choose P, I and D
parametets optimal for the controlled process. If theuser is not familiar with these methods,
also some exemplary values can be used, suitable for demonstration of the PID work process
controlling slow processes (like heating 1liter of water using a 1000 Watt heater).
Mode
: PID,
Dead zone
: 0,
for
Controller parameters
block parameters:
P Coefficient
: 5,
I coefficient
: 10,
D coefficient
: 1,
Differentiated signal
: feedback (measured),
for
Controller output
block parameters:
Offset
: 0,
Low output limit
: 0,
High output limit
: 100,
for
Initial conditions
block parameters:
Init type
: No init (internal state 0),
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