Appendix
7.2 Alarming
The following alarm conditions are continuously monitored by the temperature controller:
• Absolute temperatures (high and low)
• Relative temperatures (in two bands around the set value)
The following hardware conditions related to the sensor can also be linked to the temperature controller:
• Open thermocouple: broken wire to the temperature sensor
• Back voltage: a voltage outside the permitted range is present at the temperature sensor
• Reverse thermocouple: temperature sensor is connected with the wrong polarity
If a current sensor is connected, then the following signals can be linked to the temperature controller:
• Short circuit
• Open circuit
• Leakage current
Requirements
Development environment target platform PLC libraries to include
TwinCAT 3.1.4006 PC or CX (x86) Tc2_TempController
7.3 Self-tuning
The self-tuning algorithm is based on the classic inflectional tangents method. This method was first
developed by Ziegler and Nichols. It is assumed that a linear P-T1 loop with a delay time is being examined.
The maximum rate of change is determined following an experimental step. This is achieved through
TC3 Temperature Controller 45Version: 1.1
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