Product Description - Beckhoff TwinCAT 3 Manual

Product description

2 Product description
The TwinCAT temperature controller is a universally applicable PLC function block for monitoring and
controlling a wide variety of temperature-dependent processes. The controller can be operated in following
modes:
• automatic (closed loop) and
• manual (open loop)
The control value can be accessed in digital or analogue form. The digital control value is pulse width
modulated (PWM) signal. A two-point or three-point output is also available. The control value is limited to
the permitted maximum and minimum values.
The set value is also limited to permitted minimum and maximum values, and can also have steep slopes or
ramps. A bit is available in the function block interface that provides easy switching from the set value to a
stand-by set value. A soft start can be parameterised to support "heater baking". This involves the set value
(optionally ramped) being initially set to a low value, held constant for a certain time, then changed to the
true set value (again optionally ramped up).
The actual value can be digitally filtered.
The control algorithm is PID-based. An additional pre-regulator can be inserted in order to minimise the
overshoot.
The controller has a variety of parameterisable monitoring functions. There is:
• tolerance band monitoring (two different tolerance bands),
• absolute value monitoring,
• sensor monitoring (open, back voltage, reverse) and
• monitoring of the heating current (open, short circuit, leakage current).
There is an algorithm for determination of optimal controller parameters that greatly simplifies the process of
commissioning the controller. This algorithm evaluates a step response, and uses a method of inflectional
tangents to determine the maximum speed and delay time of the loop. This data allows a controller to be
specified according to the rules of Chien, Hrones and Reswick. The parameters for the pre-controller are
also determined here. If the controller parameters are already known, then the controller can also be
operated using these externally supplied parameters.
Commissioning the controller in stages [} 17]
Documentation of the Function Block [} 21] and the structures.
6 Version: 1.1 TC3 Temperature Controller