Dear user,

Hi, I have created several new continuous PID control loops using Standard PID Control. I would like the functions to start in automatic mode (MAN_ON = FALSE, i.e. using the output from the PID algorithm) rather than in manual. When I look at the offline versions of the DB's, the default position for the switch is PID (MAN_ON = FALSE). However, whenever I close the Standard PID Control configurator and restart it and go online, the default online position of the switch is MAN_ON = TRUE which means my loops are running in manual mode by default which I do not want. This means that if the PLC is restarted I have to manually set all my PID loops to run in auto which seems ridiculous. Am I missing something really obvious?

 Just to add some point regarding PID in general:

1. In case of CPU entering the STOP mode, it is wise to put PID in manual mode while in transition from STOP-->RUN.This is possible by adding code in OB10x(e.g OB100). In such a case a , some actuators may goes to their safety position that PID in auto is meaningless.
   
   
2. PID in manual and unit shutdown in case of CPU restart is beneficial from package of plant safety requirement.Operator intervention is required for start up again.
   
   
3. To have a deterministic PID mode , use OB100 to determine that.You can use some instrumentation tools to keep the valve locked in the previous position and when CPU restarting put the PID in auto mode and similar SP and PV will avoid huge actions on valve on start up.
   
   
4. Configurators are like VATs but give an overview of the overall algorithm.Check your program that the signals you are talking about are not overwritten somewhere in your program.
   
   
5. You can also read more about difference between actual and initial values in a DB HERE.

I hope it helps,

hdhosseini