16-02-2013, 10:55 AM
PID Temperature Controller
[attachment=51143]
Background
Applications
Plastic injection molding
Powder paint
There is a need for quick and accurate temperature control
Two solutions
Sensor with simple logic controller
Smart I/O controller
Allen Bradley 1771-TCM
Uses PID controller
8 independent control loops
Heating or cooling control
Auto-Tuning software
Speeds up design
Accurate gains
Analog or digital control
Standard PLC-5 rack mount
Control Loops
Thermocouples used for feedback
Open loop detection
Disable unit or output constant value
Data collected in the TCM is given to the PLC
PLC controls actuator
PID Auto-Tuning
Auto-Tune calculates PID gains
Gains are stored in TCM module
Gains must be read into PLC data table
TCM can be set to slow, medium or fast response time
TCM memory is volatile
TCM must have gains sent to it or auto-tune whenever power to the module is lost
PID Fine-Tuning
Fine tuning can be done manually
Too much overshoot
Decrease P and I
Increase D
Too slow
Increase P and I
Decrease D
Analog vs. Digital Control
TCM module has two possible outputs:
Analog control allows PLC to set the temperature of the heating / cooling device
Digital control gives the PLC the duty cycle for the actuator
[attachment=51143]
Background
Applications
Plastic injection molding
Powder paint
There is a need for quick and accurate temperature control
Two solutions
Sensor with simple logic controller
Smart I/O controller
Allen Bradley 1771-TCM
Uses PID controller
8 independent control loops
Heating or cooling control
Auto-Tuning software
Speeds up design
Accurate gains
Analog or digital control
Standard PLC-5 rack mount
Control Loops
Thermocouples used for feedback
Open loop detection
Disable unit or output constant value
Data collected in the TCM is given to the PLC
PLC controls actuator
PID Auto-Tuning
Auto-Tune calculates PID gains
Gains are stored in TCM module
Gains must be read into PLC data table
TCM can be set to slow, medium or fast response time
TCM memory is volatile
TCM must have gains sent to it or auto-tune whenever power to the module is lost
PID Fine-Tuning
Fine tuning can be done manually
Too much overshoot
Decrease P and I
Increase D
Too slow
Increase P and I
Decrease D
Analog vs. Digital Control
TCM module has two possible outputs:
Analog control allows PLC to set the temperature of the heating / cooling device
Digital control gives the PLC the duty cycle for the actuator