Temperature Controller - Staveb AG

3-22 Configuration and Basic OperationThe following table provides some additional details:Table 3.DAt Start of Program Execution(Self-Tuning ON)1. The set point at the start of programexecution differs from the set point (seeNote 1) when the previous SRT wasexecuted.2. The difference between the controlledtemperature at start of programexecution is larger than the currentproportional band (1.27+4°C) or the STstable range, whichever is larger.3. The controlled temperature at the startof program execution is smaller than theset point during reverse operation, and islarger than the set point during directoperation.4. No reset from input errorWhen Set Point is Changed(Self-Tuning ON)1. The new set point differs from the setpoint (see Note 1) used when theprevious SRT was executed.2. The set point change width is larger thanthe current proportional band1.27+4°C orthe ST stable range whichever is larger.3. During reverse operation, the new setpoint is larger than the set point beforethe change; and during direct operation,the new set point is smaller than the setpoint before the change.4. The temperature is in a stable state (seeNote 2). (An equilibrium state [seeNote 3] is acceptable when the output is0% when the power is turned ON.)Note 1: The previous SRT-implemented set point is called the set pointobtained by calculating the PID constant by the previous SRT.Note 2: In this state, the measurement point is within the ST stable range.Note 3: In this state, the change width of the PV every 60 seconds is at the STstable range or less.New PID constants are not calculated by self-tuning (ST) for the currentlyconfigured set point in the following instances:• When the PID constants have been changed manually with ST set toON.• When auto-tuning (AT) has been executed.Self-Tuning (ST) Stable RangeThe self-tuning (ST) stable range is a mechanism which allows you todetermine the condition under which the ST (self-tuning) function occurs.In this example, set the ST stable range will be configured to 20°C.Example Operation Procedure1. Select the ST Stable Range parameter by pressing the M key in theAdvanced Setting function group. To move to this function group, seep. 4-21, To Move to the Advanced Setting Function Group.Publication 900-UM003C-EN-E - January 2004