Instructions
9.1 PID_Compact
PID control
248 Function Manual, 03/2017, A5E35300227-AC
PID_Compact is called in the constant time scale of a cycle interrupt OB.
If you call PID_Compact as a multi-instance DB, no technology object is created. No
parameter assignment interface or commissioning interface is available. You must assign
parameters for PID_Compact directly in the multi-instance DB and commission it via a watch
table.
The actual values of retentive variables are only updated when you download PID_Compact
completely.
Downloading technology objects to device (Page 44)
When the CPU starts up, PID_Compact starts in the operating mode that is saved in the
Mode in/out parameter. To switch to "Inactive" operating mode during startup, set
RunModeByStartup = FALSE.
In automatic mode and during commissioning, the reaction to error depends on the
SetSubstituteOutput and ActivateRecoverMode variables. In manual mode, the reaction is
independent of SetSubstituteOutput and ActivateRecoverMode. If ActivateRecoverMode =
TRUE, the reaction additionally depends on the error that occurred.
Configuration editor
> output value
> Set Output to
Not relevant FALSE Zero (inactive) Switch to "Inactive" mode (State = 0)
The value 0.0 0 is transferred to the actuator.
FALSE TRUE Current output value while error is
pending
Switch to "Substitute output value with error moni-
toring" mode (State = 5)
The current output value is transferred to the
actuator while the error is pending.
TRUE TRUE Substitute output value while error
is pending
Switch to "Substitute output value with error moni-
toring" mode (State = 5)
The value at SubstituteOutput is transferred to the
actuator while the error is pending.
In manual mode, PID_Compact uses ManualValue as output value, unless ManualValue is
invalid. If ManualValue is invalid, SubstituteOutput is used. If ManualValue and
SubstituteOutput are invalid, Config.OutputLowerLimit is used.
The Error parameter indicates if an error is pending. When the error is no longer pending,
Error = FALSE. The ErrorBits parameter shows which errors have occurred. ErrorBits is
reset by a rising edge at Reset or ErrorAck.
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