Siemens SIMATIC S7-1200 Function Manual page 179

If values not equal to 1.0 are configured for the proportional action weighting or the derivative
action weighting, setpoint changes even within the dead zone affect the output value.
Process value changes within the dead zone do not affect the output value, regardless of the
weighting.
Dead zone with deactivated cooling or cooling factor (left) or activated cooling and PID
parameter switching (right). The x / horizontal axis displays the control deviation = setpoint -
process value. The y / vertical axis shows the output signal of the dead zone that is passed
to the PID algorithm.
Control zone width
If the process value exits the control zone around the setpoint, the minimum or maximum
output value is output. This means that the process value reaches the setpoint faster.
If the process value lies within the control zone around the setpoint, the output value is
calculated by the PID algorithm.
The control zone width for heating or cooling is only set automatically during the pretuning, if
"PID (temperature)" is selected as the controller structure for cooling or heating.
The control zone is deactivated by setting the control zone width = 3.402822e+38.
If cooling is deactivated in the basic settings or the cooling factor is used, the control zone
lies symmetrically between "Setpoint - control zone width (heating)" and "Setpoint + control
zone width (heating)".
If cooling is activated in the basic settings and PID parameter switching is selected as the
method for heating/cooling in the output settings, the control zone lies between "Setpoint -
control zone width (heating)" and "Setpoint + control zone width (cooling)".
PID control
Function Manual, 03/2017, A5E35300227-AC
Using PID_Temp
6.2 Configuring PID_Temp
179