Hi,

I have a problem with PID_Temp on a S7-1215 CPU. Sometimes after powerON and activating the PID it seems like the PID is using the wrong parameters. We get very high over- and undershoots. See attached picture. Only after shutdown power to the PLC and powerON again the problem goes away. On the left of the picture the problem can be seen. The right side is after power OFF/ON.

I have 4 PID_Temp controllers. It seems like when this problem occurs, always 2 PID_Temp controllers have this problem, The other 2 are fine.

Mode after CPU-start is set to Automatic.

I use the EN of the PID-block to start/stop the PID. All 4 PID's are in a OB30.

I tried manual PID-parameters. Did not solve this.

How can i solve this strange behaviour.

Regards,

Maurice Theeuwen

hi,

please show us, how the Parameters of your PID´s.

What cycle-time has your OB30?

regards,

Cycle-time of OB30 is 100ms.

See picture for parameters. These are the manual entered parameters. The same as after tuning.

The other 3 PID's parameters are almost the same.

Other information:

- TIA portal V13 SP1 update 8

- PID_Temp V1.0

- CPU 1215 V4.1

Regards,

Maurice Theeuwen

HI, 

Did you solve this problem?

Actually, i have the same error in a S7-1516. 

I have 6 PID using the block CONT_C and only one doesnt work.

Please share information if you solve it.

Regards.

Hi,

No the problem has not been solved. About 3 months ago i reset the PLC and uploaded the software. This seemed the solution. 3 months no problems, up till this week the problem was back again.

Next step will be replace PLC or update the software from V13 to V14.

Last time i tried the software update to V14 but got a problem with serial communication with a printer, so a canceled the update.

Regards,

Maurice

Hi,

I just had contact with our customer. No further action will be taken to solve this problem. Because the problem does not happen frequently they make a procedure to check the temperatuur after startup and restart the machine when to problem occurs.

If someone finds a solution. Let me know.

Regards,

Maurice