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| 7/27/2011 12:56 PM | |
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Posts: 267 Rating:
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Hello, "One problem Iwas experiencing was when my PV signal reaches its upper or lower limit, the PID_COMPACT block goes into manual and the output just drops off. I used the PID Auto Reset block that was posted in that discussion and it seemed to work most of the time. But sometimes there is no error and the state is 3 but the output doesn't change until I change sRet.i_Mode to '4' and then back to '3' again." - Increase the upper limit and decrease the lower limit to eleminate this behaviour. "2 If you want that the PID runs in automatic mode without automatic optimization, you need: a. Set the checkbox “Use manual PID parameter setting“, in the Configuration, tab “Advanced settings”. b. Set “3” to the variable “sRet.i_Mode” of the respective instance DB c. Extra tips: a. if you intend to Set the checkbox “Use manual PID parameter setting“, do it, but after that change the mouse focus before to close the Configuration windows. Else your check will be loose." - I try to find this in the STEP 7 Basic V10.5 SP2 manual, but I cannot find it. "One problem I am experiencingalso is the error "0000_0800". According to the help this means: Sampling time error: The "PID_Compact" instruction is called in the cyclic program or the settings of the cyclic interrupt were changed. Can someone please elaborate on this error? I am calling the FC with this PID_COMPACT in OB200, every 100ms. Is this correct?" -In my oppinion this settings are right. Did you check the this FAQ: http://support.automation.siemens.com/WW/view/de/42321471 "Also, when I download this FC, without making any changes, I cannot view it online because it says Offline does not match Online. I am editing sRet.i_Mode(I set this to '3' when in Auto and '4' when in manual), sRet.r_Ctrl_Gain, sRet.r_Ctrl_td etc in the FC.Does thatmatter?I edit these via SCADA. Should I edit the Instance DB values directly?" -I would always download the whole blocks to the PLC to be sure, that the data isn't inconsistent. Value changes have to be always in the Instance DB. |
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