Hello, I am quite a newbie in PLC programming. I am trying to add a PID control function into a ladder program of FX3U PLC that was made by the person before me who used GX developer. I have read the manual, but still not sure if I understand it correctly or not. Please help me with questions below:
1. For parameters [S3]+1, how do I set the bit value? My understanding is that I need to align the bits I want, and then convert to Decimal number to set it, is this correct?
i.e. If I need bit to be 0100001, do I set the parameter to 33?
2. How do I know if I am doing backward or forward operation? I think what I am doing is feedback control loop, does this mean it is a backward operation?
3. If I set auto tuning bit (parameter [S3]+1 bit#4) to 1, will this make the the program to run auto tune everytime I start the PID?
4. For parameter [S3]+22, [S3]+23 and [S3]+24, the manual said it will be occupied. Does this mean it will be preset by the program which I shouldn't mess with them? But how do I set the output upper and lower limit in [S3]+22 and [S3]+23?
Also, I couldn't find any example of PID parameter setting in the manual. Not sure if I missed any important section in the manual. So please point out to me if there is any example. I also attached the manual on the PID page just for a quick reference.
Thank you in advance for the help.
FX3U Programming PID.pdf
