PID instruction in CJ1M trouble

[Linhvct]

Dear all, I have used PID instruction in my program, but it always result zero value and I have no idea what is going on. Is anyone have experience like this before and tell me where I'm wrong!? I attached an emage below hope you can help me figure it out. Thank you!

[Mendon Systems]

Is that screenshot online from the PLC or from the simulator?? PID does not work in the simulator.

[PMCR]

You are using a battery backed memory area (DM) for the background data manipulation for the PID instruction (C+7 - C+38). You should clear this area (D7907 - D7938) prior to starting the PID instruction. 'Stale' data in this memory area can cause the instruction to not function correctly. The other thing to check is the P_ER bit immediately after the PID instruction (before the SCL instruction). Put a normally open contact of P_ER and an output that you are not using (W511.15?). Monitoring this will tell you if the PID instruction is causing an error. If it is, the help for the PID instruction will tell you what might be causing the error.

[Linhvct]

Thank you, It's true that I did used one DM in C+7 to C+38 acidently. I fixed it and it's ok know

[chou]

Hi Linhvct,

Can you forward the example of your previous program for this PID function ?