PID Control FB41

Hi, I'm pretty new in the world of PID controls with a PLC but I searched a bit on google and know a bit of it but the problem I got is that whatever I do the LMN of FB41 wont get a output at all also I tried the LMN_PER but that didn't work also. The hardware what I have is this:
CPU-315-2-DP
2 I/O simulation modules (currently not used in this project)
a Hitachi EH-RIO profibus module with the AI and AO
and a simple potmeter to simulate the AI wich works fine.
I scale the input with the FC105 Scale block.
The parameters I have for FB41 in OB35 100mS:
Cycle : 100mS
SP_INT : MD* (setting these value with a variable table)
PV_IN : My scaled AI input
DEADB_W : 0.0
LMN_HLM : 100.0
LMN_LLM : 0.0
LMN : MD* (unscaled to my AO)
This was the first settings I had but whenever I changed the input there wasnt any change at the output LMN.
I also tried it with the peripherie input and output directly from the AI and AO.
I also tried an example program wich I found on this forum but also the same problem, no LMN/LMN_PER output.
Also in Simulation mode it doesnt work on both projects.

have you entered the gain ?

Your configuration parameters looks ok.

have you downloaded the DB generated by the FB41 to the PLC?

I would suggest to re-download the DB after making any changes in the PID parameters.

The default value for MAN_ON is TRUE so this will be your problem. Make it FALSE. Here's my example working with P term only:

cjd1965 said:

have you entered the gain ?

Click to expand...

I tried it with and without.

rohan tandon said:

Your configuration parameters looks ok.

have you downloaded the DB generated by the FB41 to the PLC?

I would suggest to re-download the DB after making any changes in the PID parameters.

Click to expand...

Yes, I did redownload the DB after making changes.

L D[AR2 said:

The default value for MAN_ON is TRUE so this will be your problem. Make it FALSE. Here's my example working with P term only:

Click to expand...

I'll try that. I didn't know that was the standard

Edit: I tried the sample you provided me but still no LMN output
Edit2: I do get an output on LMN now but it stays at the value of the LMN_HLM value no matter what I change it in. I'm using the same settings as you only different is that I'm using scaled values and LMN_HLM at 100.0 and LMN_LLM at 50.0
Edit 3: It fully works now It seems that S7 wasn't processing the values to the DB all the time so I edited the manual value to false in the DB itself and now it works. Thanks for your help all

maybe you like my version with a multi PID set parameters...
http://blog.ranghetto.com/?p=13