3-Point Stepper Control with SIMATIC S7-1200
For products: 6ES7211-1AD30-0XB0; 6ES7211-1AE31-0XB0; 6ES72
PROBLEM: The valve of a mixer tap shall be controlled according to a desired given temperature. A three-way mixing valve with valve actuator is used. The valve is digital controlled in both directions. This is referred to as a 3-point stepper control.
Varying the valve position can yield any mixing ratio of hot and cold entering water and so the water outlet temperature.
SOLUTION: For SIMATIC S7-1200 as of firmware V2.0, the development environment STEP 7 V11 provides the "PID_3Step" 3-point stepper control block.
