106
CONTROL MODES
PID Control
Following graphs exemplify how the input parameters work.
Control out is proportional with the Set point variance, the sum of previous control errors and an
estimation of the future ones.
SP
Control period
mode Low
Deviation
Process value
Relay
out
Analog
out
PID control
Figure 40:
PID Control Mode Low, Relay & Analog Out
Realy On time has a guaranteed minimum to prevent stressing the actuators electrically or
mechanically.
SP
Control period
PID control
Deviation
Process value
Relay out
Relay out with min.
On time control action
Min. On time
mode Low
Figure 41:
PID Control Mode Low, Relay Out with Minimum On Time
